Graduate and postgraduate educational challenges during the COVID-19 pandemic period: its impact and innovations—a scoping review

Background The coronavirus disease 2019 (COVID-19) pandemic has transformed the global view of education, including graduate and postgraduate education making the development of an alternative approach in times of social isolation an academic imperative. The present review aims to investigate the challenges experienced among undergraduate and postgraduate education and the strategies adopted to address these challenges during the pandemic. Method The preferred reporting items for the systematic review and meta-analyses extension for Scoping Reviews (PRISMA-ScR) were followed. The aim was to include journal articles published in the English language that discussed the influence of the pandemic on educational processes and applied innovative approaches as a solution to educational challenges. From January to August 2020, PubMed, EMBASE, and Google Scholar were searched for articles, yielding 10,019 articles. Two groups of authors examined the retrieved articles separately to avoid any risk of bias. The title and abstract of the articles were used for scrutiny, followed by full-text screening based on the established inclusion and exclusion criteria. The facts and findings of the studies were also discussed based on per capita income, literacy rate, and Internet accessibility. Results Thirty of the obtained articles were included in the study. The selected articles were from North and South/Latin America, Asia & Pacific, South Africa, and Europe regions. Nineteen of the selected articles dealt with undergraduate education, ten with postgraduate, and one with both groups. The affordability of digital devices and the availability of Internet services were the major challenges for low- and middle-income economies. The ZOOM platform has been adopted by more than 90% of the education systems. Conclusion Means of communication, including visual media, digitized content, and other web-based platforms, have been recognized as efficient learning and training tools, but have not been fully accessible for mass application and use due to the lack of availability of resources, their cost, and insufficient training among the users. In light of this review, it is suggested that harmonized and collaborative efforts should be made to develop cost-effective and user-friendly tools to overcome the current challenges and prevent future educational crises. Systemic review registration The review was not registered. Supplementary Information The online version contains supplementary material available at 10.1186/s13643-023-02359-2.


Introduction
In late December 2019, a pneumonia-like disease caused by a novel coronavirus named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in Wuhan, China.The disease was later named COVID-19.The disease spread worldwide and was declared a pandemic by the World Health Organization (WHO) in May 2020.Since no treatment options were available, strict preventive measures were recommended [1].Visiting educational institutions and workplaces was banned, and both tourism and public gatherings were prohibited.In addition, citizens' freedom of movement was restricted and controlled nationally and internationally to minimize and break the chain of infection [2,3].Normal life activities were disrupted and behavior and lifestyle changed enormously [4].The education system has been one of the biggest casualties of the COVID-19 outbreak around the world, where the rate of spread was expected to be high due to the large and crowded gatherings and therefore closed as a priority [5].Regular classroom activities were discontinued worldwide, and the continuity of education during the pandemic was one of the top concerns for each country [6,7].
Distance learning or an online education system has been suggested by educators/government bodies as an effective alternative to face-to-face learning [6].Various online teaching methods were adapted within a week or two, while some institutions opted for the hybrid educational model to complete the curriculum with the planned academic calendar.The exams were carried out via online platforms [8].However, an uninterrupted Internet connection is the backbone for conducting online education.According to the United Nations International Children's Emergency Fund (UNICEF) report published in 2017, more than half of the world's population had no access to the Internet (Fig. 1) [9].Considering the need, Internet accessibility has increased and Internet users are on the rise after the pandemic [10].The latest information regarding Internet users country-wise is shown in Fig. 2 [11].
Besides Internet accessibility, digital literacy is also an essential element required to embrace emerging technologies and communicate in today's world [13].Digital literacy is the ability to create, evaluate, communicate, integrate, understand, manage, and access information appropriately and safely through digital devices.These include media literacy, information literacy, information and communication technology literacy, and computer literacy [14].Conversely, according to a 2016 report by the United Nations Educational, Scientific and Cultural Organization (UNESCO) Statistics Institute, nearly 750 million adults worldwide lack basic literacy skills.This is another major challenge for educating the masses who are overwhelmingly in the 15-24 age group.Some regions have the lowest reported literacy rate with 50% of the world's illiterate population living in South Asia, followed by sub-Saharan Africa (~27%).East and Southeast Asia (10%), North Africa, West Asia (9%), and Latin America (4%) [15].Shockingly, the report also pointed out that global literacy rates increased by just 4% between 2000 and 2015.The 2020 global literacy rate data provided on the World Atlas website is shown in Fig. 3 [16].
In an old but very descriptive and conclusive study, Robert J. Barro demonstrated that there is a linear relationship between a country's gross domestic product (GDP) and literacy [17].The GDPs of different countries according to the 2019 World Bank report are shown in Fig. 4, showing the inequality between different continental regions [18].In addition, the quality of the education provided is considered an essential element for national development and is therefore linked to GDP per capita [19].The per capita income of different countries determines the technological purchasing power of the population to cope with online teaching methods (see Fig. 5 of the World Bank 2019 report) [20].
This urgent need and lack of resources for the adoption of distance learning amid the pandemic have severely impacted the entire education system around the world, particularly in developing countries where face-to-face (physical) interaction in the classroom is the traditional way of teaching [21].When delivering content, meeting curriculum requirements is more difficult when there is a significant need for hands-on demonstration or laboratory work.In addition, it was observed that the theoretical aspects of the courses were being taught relatively at ease and with fewer difficulties as compared to the practical work [22].According to a UNESCO report, this scenario has affected, in one way or another, almost a billion learners worldwide, particularly in the professional and higher education sectors [23].
In summary, the development of online learning, during the COVID-19 outbreak, presented a new challenge to the already ailing education system.The objective of the present review is to identify the major issues that have emerged in undergraduate and postgraduate education during COVID-19 and to identify the strategies that universities of different countries are adopting to address these challenges.In addition, the challenges and the importance of the implemented strategies are examined in the context of per capita income, literacy rate, and Internet availability in different parts of the world.This work offers possible alternative learning and teaching approaches to adopt during times of social distancing and school closures.The work also presents some suggestions to prevent such academic provocations in the future.

Methodology
A systematic review of the literature was performed based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) reporting guidelines [24].The PRISMA-ScR checklist can be found in supplementary Table S1.Because the study aimed to include articles related to the major education crisis during the COVID-19 pandemic, the time period was limited to January-August 2020.The PubMed, EMBASE, and Google Scholar (advanced search) databases were searched using the keywords "('coronavirus' OR 'SARS-CoV-2' OR 'COVID-19') AND ('graduate*' OR 'education*' OR 'teach*' OR 'train*' OR 'student*' OR 'challenge*' OR 'solution*' OR 'innovation*')".The search keywords were set to identify and recognize all the studies published on the challenges facing undergraduate and postgraduate education during the COVID-19 conditions and to cover the new methodologies being used as solutions to these challenges.

Eligibility criteria
PCC (Population, Concept, and Context) was applied for the inclusion of sources in the scoping review [25].For the current study, undergraduate or postgraduate students were selected as the test population.The concept of this review was to examine and identify the major educational issues that have arisen during COVID-19, along with possible alternative and widely accepted strategies adopted by various regional institutions to address the challenges.The outcomes were defined as responses to solutions or innovations used to address remote learning during the pandemic.In this context, the literature included research letters or articles, letters to the editors, and short communication in English, discussing the impact of the COVID-19 pandemic on undergraduate and postgraduate education and implementing innovative approaches as a solution to the challenges.Any literature deemed relevant according to the eligibility criteria was shortlisted for full-text screening based on the title and abstract.The review excluded the studies that did not discuss the challenges directly linked to the COVID-19 pandemic and did not apply any strategic solutions to address the education crisis at the undergraduate or postgraduate level.In addition, review articles, surveys or questionnaires, prospective pilot studies, books, book chapters, reports, papers based on primary and secondary education, and those published in a language other than English were also not included.

Data collection and quality assessment of the studies
The selected studies were screened and evaluated for their eligibility using the predefined inclusion and exclusion criteria.The redundancy in the two databases was first identified using the EndNote application version X7.8.The first author provided the idea and fully directed the study.Articles retrieved were filtered into pairs by the second, fourth, eighth, and ninth authors independently on the basis of title and abstract.The articles whose eligibility was unclear were selected for a full-text review.These articles underwent further evaluation in a group of two independently by the second, third, sixth, and seventh authors, to ensure that the data from selected studies address challenges and the implementation of solutions or innovations in undergraduate or postgraduate education in the situations of the COVID-19 pandemic and prevent any risk of bias.Finally, those that met the predefined selection criteria were selected for data extraction.
The research articles selected for data extraction were reviewed and their key findings and facts were collected and sorted into a separate file.After completing the scrutiny of all articles, the findings were accumulated in two categories: [1] "challenges" and [2] "solutions or innovations." The "solutions or innovations" have also been categorized into various secondary themes, namely teleconferences, webinars, virtual classroom and video conferences, new application or software design, social media platforms, simulation, and virtual reality.The strength of the adopted strategies (solutions or innovations) of the different online platforms used by different institutions was evaluated and the inference was made.

Search outcomes and analysis
Out of 10,019 articles, the search items returned 8474 articles from PubMed, 1172 from EMBASE, and 373 from Google Scholar.After removing the duplicates, 9863 articles were obtained.A total of 512 articles were selected for a full-text review based on their title and abstract, and upon full-text screening, a total of 30 articles were selected and subjected to analysis for final data extraction.The articles were based on qualitative studies generally from the North American region followed by Asia and the Pacific, Europe, and South/Latin America.Figure 1 outlines a detailed description of the present research.
The two categories of the results, i.e., challenges and solutions/innovations with the secondary themes are described as follows.

Challenges
Nineteen of the thirty articles addressed the challenges faced by undergraduate students, ten of the articles addressed postgraduate students, and one addressed both groups.
The cessation of all academic activities, reduced inperson educational opportunities, poor Internet connections, lack of technical understanding, limited resources, difficulties in assessment, pandemic-related stress, or anxiety were the most commonly reported educational challenges during the COVID-19 pandemic [26][27][28][29][30][31][32].The reduction of hands-on learning and the cost burden of expensive online educational platforms available were the main challenges in undergraduate and postgraduate education [33][34][35][36][37].

Solutions or innovations Teleconferences, webinars, virtual classrooms, and video conferences
The majority of the articles selected, around 23, are related to teleconferences, webinars, virtual classrooms, and video conferences (see Table 1).Most of these articles were from North America, generally the USA.ZOOM, WebEx, Microsoft Team, Mentimeter, Redmond, Wash, Pascsbin, Google Classroom, Echo360, GoToMeeting, Google Meet, and Adobe Connect received positive feedback as online learning tools in these regions [27,28,[36][37][38][39][40][41][42][43][44][45][46].Some of the articles were from Asia and Pacific, including countries such as India, Singapore, Japan, Korea, Pakistan, and China.ZOOM, Google Meet, Microsoft Team, and WebEx were reported as platforms in these regions [30,31,34,47].The UK and Ireland successfully adopted ZOOM, GoToMeeting, and EMIS Health [48,49].Likewise, ZOOM, Moodle, and WhatsApp were adopted in South Africa [50].In South America, on the other hand, ZOOM, Google Classroom, Microsoft Team, and Athena Hub were used for online education [51].In addition to the above platforms, social media platforms like Facebook Live, YouTube, What-sApp, Snapchat, Telegram, Instagram, WeChat, and Twitter were leveraged to eliminate technology-based challenges.The hybrid education system (mixture of online and physical instruction), interactive online learning through face-to-face virtual meetings, and non-interactive online learning through the provision of recorded videos and supplemental reading materials were seen as the widely preferred approaches in the Asia Pacific region, where limited technology resources and insufficient knowledge to operate the advanced technologies were the main problems.ZOOM turned out to be the most used and widely preferred means of communication (Table 2).In the current review, more than 90% of the studies, indicated that ZOOM is an online platform preferred by both developed and underdeveloped countries (Fig. 6).Microsoft Teams, a video conferencing application similar to ZOOM, is also widely used.Meanwhile,  telemedicine, in which patients are consulted online using telephone or video conferencing tools, has emerged as a widely accepted strategy for delivering medical education and remote consultation [41].

New application or software design
New application software called LAPP and Epidemix were developed to provide a user-friendly interface with minimized technology-related challenges.These applications received extremely positive user feedback [26].In addition, the applications can be used to easily conduct complex courses.

Social media platform
The social media platform WhatsApp was used as a teaching tool during the pandemic in Asia and the Pacific such as Pakistan and India (see Table 3).The platform has reportedly been used effectively for both training and assessment during the pandemic [53].However, the students identified a lack of real-world interaction and problems related to Internet connectivity and device availability as the main disadvantages of this teaching method identified in these studies.

Simulation and virtual reality-based tools
Simulation and online learning based on virtual reality originated in North America such as the USA and Europe such as Hungary (see

Challenges
The COVID-19 pandemic has disrupted every aspect of modern society and its social fabric, especially educational institutions.It has very negative effects, especially in developing countries.As a result, it has transformed the world's education system and forced us to redesign it.In addition, students lost internship opportunities and personal freedom, suffered personal losses, and their safety was threatened by infections and related morbidities [56].
The challenges posed by COVID-19 turned universities learning management systems and curricula upside down, particularly for various graduate programs.This has resulted in the cessation of all academic activity, reduced in-person educational opportunities, and severely restricted student access to institutions, particularly at universities where annual enrollment is mainly based on international students.The situation became increasingly unclear, with no planning and no clear end in sight, along with fears of contracting disease, a shortage of personal protective equipment (PPE) and the urgent need to maintain physical and social distancing [26,28].Social distancing measures forced students to be quarantined and relocated to remote settings.This also underlined the need for an alternative educational model [38,40,42,49].However, to ensure the provision of education for these students, online platforms such as video tutorials were introduced [53].
Institutions providing undergraduate and higher education had to deal with the consequences of the sudden closure of campuses, reduced hands-on attendance, diminished on-site learning environments, and the cessation of in-person classes [43,53].To deal with the fallout   from these consequences, institutions had to develop innovative methods to ensure uninterrupted, quality education.The education system has made a rapid transition to online education, which indeed seems to be best practice under the circumstances [48].In addition, professional graduate and postgraduate programs that offered and required internships or placements as part of their curriculum requirements had become a real problem for newcomers [57,58].Education before the pandemic featured a hands-on learning environment, case-based learning, and handson workshops.The Association of American Medical Colleges (AAMC) issued guidelines for students not to be allowed direct contact with patients who have tested positive for the coronavirus.As a result, universities prevented their students to continue hospital clerkships or other activities related to patient care [41,45].These strategies led to the discontinuation of various traditional learning activities due to the enforcement of physical distancing guidelines in classrooms and laboratories [51,59].The implementation of social distancing measures resulted in restricted access to research laboratories and restricted research on humans and animals.Retrospectives, literature reviews, and survey-based studies were the viable project options for research students.Research activities and opportunities at research institutes were also declined.The paradigm shift to e-learning was widely needed and accepted around the world.However, it could never replace the quality of learning that is mainly acquired through practical experience, such as learning instruments/equipment and troubleshooting manual skills.In addition, the transition to online education became a major challenge, with education struggling to adapt to technological innovations while COVID-19 acted as a catalyst for this slow transition [54,60].
Most undergraduate students are computer newbies.Therefore, technology-based learning became a challenge.It was seen as a barrier to the rapid shift to online education [47].A major challenge faced by the universities was the lack of tech-savvy human resources [29].Online and virtual education also raised significant concerns about student assessment, as remote assessment was difficult to monitor and making remote assessment fair was therefore a difficult task [30].In addition, poor Internet connections, lack of technical understanding, and limited resources made it difficult to provide quality education [31].
Postgraduate education was also significantly impacted by the pandemic.Theoretical learning became the only option for postgraduate medical students during the pandemic.Face-to-face classes, lectures, seminars, and conferences were reduced to a virtual environment [33].It has become difficult for postgraduate students to continue their education within a safe environment as student health was a top priority.In addition, moving practical lectures to an online medium was a difficult task.Visiting teaching opportunities were canceled [34,35].Most online education platforms are expensive which puts a heavy strain on the annual budget.The surgical residency was one of the first to be affected by the pandemic and saw a sharp drop in elective surgeries with immediate effect [36].In addition, only urgent surgeries were recommended in practice guidelines, and the cancelation of elective surgeries had a major impact on surgical resident training programs.The universities tried to meet the challenges with all available resources [61].
Social distancing strategies implemented included the use of home offices, individual reading rooms, the cancelation of conferences, and limited participation in hands-on training [37].The University of Toronto's Diagnostic Radiology Program, which covers eight hospitals with 50 residents, is one of the largest assistance programs in Canada and was also affected by the COVID-19 pandemic [44].The education system was completely switched to online education, for example practical objects based on glass slide microscopy wer replaced by virtual microscopy for dermatology education [55].
On the other hand, the students were not able to understand the course of events.They did not have enough mentoring options and could not build a team relationship.These changes had a serious impact on students' self-confidence and personality information [62,63].In addition, the most difficult challenge faced by teachers was to simulate the practical teaching in order to be able to demonstrate it easily.The education ministers of different countries suggested that education should not suffer, which is why educational tools based on virtual simulation were integrated into the education system [64].Therefore, it has become necessary for institutions to adopt alternative teaching methods and explore virtual delivery of education through social media or online platforms [65].

Solutions
Distance learning (DL) or technology-based learning (TB) is nothing new to many developing countries.The approach is used as synchronous learning based on real-time interactive lectures and asynchronous learning based on self-study and discussion in various forums such as emails [66,67].Video conferencing has been used in education since the 1960s [68].Flexibility, accessibility, reduced costs, portable learning materials, self-based learning, time efficiency, and reduced risk are some of the stated benefits of online learning.Even before the current pandemic, online platforms are being used by various institutions around the world, especially in developed countries [69,70], showing that online education as an academic norm is not only associated with the COVID-19 pandemic and several online education-related videoconferencing software have been used, including Zoom, Skype, and Cisco Webex [71,72].
Zoom turned out to be the most widely used videoconferencing platform for synchronous education, which offers useful features for smooth communication, such as these include a chat board, a hand-raising system that increases student attention and engagement, screen sharing that allows presenters to view slides, and the recording of lectures for later viewing [34,73].It could be observed that not only the students, as a generation with an affinity for social media, accepted this form of learning, but also that the feedback from the faculty members in a study showed that, despite the use of new teaching methods, there was a significant degree of satisfaction with online teaching ruled [74].
Distance learning provided an opportunity for educators to develop a close connection and dialogue with students, particularly those with intellectual disabilities and learning difficulties [51].Student reviews were mixed, with some advocating a blended strategy for the post-pandemic era, others expressing a negative opinion of online learning, calling it an unsuitable mode, particularly for medical education, and still others expressing the need for one comprehensive training to adopt the online mode learning.Studies have shown that most students favor hybrid learning because it overcomes some traditional teaching barriers but requires appropriate teacher training and institutional support [74].The flipped classroom is a common pre-pandemic approach and can therefore be used for asynchronous and synchronous lessons [75].Virtual meetings were found to be more engaging for students as they have the feel of a live presentation, and online video lectures and webinars are expected to continue post-pandemic due to greater international exposure and lower costs [61,76].
It is believed that while providing valuable content to students, most online education platforms lack the ability to provide economically personalized feedback.For this reason, a web-based mobile platform called LAPP was set up.This application connects students with tutors remotely via their phones.Students can submit their exercises and receive feedback via video, drawing, audio, or text content.Almost 3700 replies were reported as successfully submitted.Another application, Epidemix, was developed to provide security and convenience for teachers and students.The applications can be used on a user-friendly interactive interface or on a mobile phone and are free for all users [26].
Social media is a tool that allows information to be shared in various formats, including videos [77].There has been an increasing trend to use social media for teaching and learning purposes, and a number of social media platforms such as Facebook, WhatsApp, and Instagram have been used for collaborative learning and better communication [33].A preference for "YouTube" for technical lectures can already be seen in the literature, as videos are a useful, expressive, and easily accessible information tool [77].
YouTube is the most popular source of tutorial videos because of its free content, ease of use, and familiarity among web users [77].However, an evaluation of You-Tube videos revealed that more than 95% of the videos watched by students for learning purposes were of poor educational quality.Therefore, it has been suggested that academics must conduct a critical evaluation of YouTube videos before proposing them to students [33,53,78].Likewise, the Telegram application is considered a valuable mobile application with numerous utilities and many helpful features, including easy access to educational videos, no file size or file format limitation, unlimited member capacity, good connectivity and security, and subscriptions to journals and e-books without the need a browser or website support.Some limitations such as limited group member capacity and file-sharing ability have been found to be associated with applications such as WhatsApp and Facebook [79].Although these two applications are considered to be widely used platforms worldwide that offer free services.The applications provide opportunities for knowledge sharing, assessment tools, and cognitive enhancement, even when resources are scarce [33].WhatsApp is reported to have been used effectively for both training and assessments during the pandemic.However, students cited a lack of real-world interaction and problems related to Internet connectivity and device availability as the main disadvantages of this teaching method [53].
The main advantages of using social media platforms for teaching include avoiding wasted time, easy curriculum coverage, standardized assessments, preparing and conducting exams with the active participation of students, economic feasibility, familiarity with technology, and formative assessments continue academic education in an effective manner [33,53].However, the few inherent disadvantages include the lack of hands-on training and real-time skills-based learning, the risk of cheating during an online assessment, and limited experience with a variety of real-world scenarios [33].
Simulation-based training has been suggested as the main solution for training practical skills [52].Various simulation techniques have been developed or used.These techniques are often based on virtual reality such as the LapSim simulator, are based on 3D models such as silicon 3D simulation kits, or are based on real-time hands-on experiences such as head-mounted camera devices and whole slide imaging [62,[80][81][82][83].Although many of the simulation-based platforms are considered quite expensive and require a fast Internet connection, they allow learners to see and interact with the lecturer and offer the best alternative for technical students during the period of social distancing [62,80].

Strengths and limitations
The strength of the present study is in providing an indepth overview of the strategies implemented by different universities in response to the educational challenges during the pandemic.It also summarizes the innovative solutions adopted in the selected studies to reduce the educational gap at the time of COVID-19.The research articles generated from the databases were included, such as editorials, letters, and letters to the editors.However, there may be some limitations, for example, the data obtained from selected databases did not contain information on educational approaches for other programs, such as graphic design, engineering, and visual studies in art, but mainly related to medical education.The selected studies are unstructured and show large design variations.The selection criteria were limited to undergraduate and postgraduate education.The main source of the scientific database used was PubMed, EMBASE, and supplemental searches were provided by Google Scholar.

Remarks
The present study offers practical and experienced solutions adopted by several universities from both developed and underdeveloped countries for the implementation of online education.Although online learning cannot replace hands-on learning and also has many limitations, it can be used effectively for study continuation in an uncertain period.Our goal was to explore the best alternative method available for the continuation of the education system, especially for college or university students, and to bridge the gap between students and education during the time of the pandemic.There has been much criticism of online education and related technologies, but the availability of these technological advances represents the only alternative solution to combating the education crisis caused by a pandemic.
Means of communication such as interactive video tools, digitized content, visual media, and other webbased platforms have proven to be efficient training and learning tools in the learning process, regardless of time and place [84].There are various social media tools like WhatsApp, Telegram, YouTube, Facebook, Skype, Twitter, Snapchat, and Instagram and other platforms like ZOOM, Google Classroom, Google Meet, Microsoft Team, GoToMeeting, WebEx, and Adobe Connect, which have proven valuable in delivering distance learning [56,77,79,85,86].But certain challenges have been observed, in particular the need for digital devices such as smartphones, laptops, or desktops and the requirement for an uninterrupted Internet connection [87].Affordability of such electronic or digital devices for people from countries with low-income economies and a per capita income of less than $1050, where basic needs such as food, clothing, and shelter are already the greatest problems, such as in Somalia, Sudan, Afghanistan, Yemen, Tajikistan, and Guinea, is another challenge that needs to be addressed [88].
In addition, the lack of electricity, which is a prerequisite for functioning electronic devices, poses an additional challenge in the least developed countries.The lack of literacy skills and the availability, accessibility, or affordability of the Internet have also been considered insignificant in these regions as classified [89].Affordability of digital devices should be ensured and Internet connectivity should be restructured by governments.
People in countries with middle economies like India, Pakistan, China, and Brazil have access to electronic devices to some extent, but uneconomical online platforms, lack of digital literacy, and lack of strong Internet infrastructure have been reported as the main barriers to online education [33,53,89,90].Social media platforms such as WhatsApp, Facebook Live, YouTube, Twitter, Snapchat, and Instagram as well as free or low-cost video conferencing tools such as Microsoft Team and ZOOM have been widely used as distance learning platforms in these regions [20,32,33,44,56,58,85].As problems with Internet availability and connectivity were recognized as major obstacles in these countries, recorded video lectures were more welcomed.Although online education continued in these countries, the lack of trained staff and limited Internet services in remote areas meant that students could not properly access the live or recorded lectures [47].However, it has been found that students in these regions favor a hybrid or blended education system [33,53,89,90].
The countries with high-income economies like the USA, Australia, Singapore, Japan, Korea, the UK, Ireland, Italy, Hungary, Canada, Chile, and Mexico have succeeded in developing effective online virtual simulation education based on 3D devices such as Echo360, LabCam, Netter 3D Anatomy, Canvas-LMS [80,81].The platforms, based on a 360-degree virtual operating room, are essential for an education system where learning is almost based on practice rather than theoretical knowledge [20,55].These digital devices and the new technologies that accompany them require practical skills and training to be able to use them.According to the UNESCO report, nearly 750 million adults still lack basic literacy skills.Therefore, digital skills and literacy pose a challenge not only for least developed countries but also for developed countries [15].In addition, although these countries have advanced digital infrastructure, inequalities in access to technology access are reported, such as in the USA, where access to technology is divided by race, income, and geography [88].Video conferencing tools with interactive online lectures and training courses on new technologies are needed.Although hands-on experience is irreplaceable, adapting to technological changes can help overcome some problems of online education [77].
This pandemic also teaches us the lesson that international organizations like the WHO should emphasize building the online education infrastructure to prevent future education crises.The role of students, teachers, and parents must be clearly defined in distance learning to foster future outcomes.Online tools and courses should be evaluated regularly, while program learning outcomes should be assessed based on attitudes, skills, and knowledge.Easy access to technology and the Internet is seen as a key solution to overcoming the main weaknesses of online education [91].In doing so, excess funds for governments and institutions must be vided by international fundraising organizations, especially for low-and middle-income countries, poor students, and digitally divided areas of high-income countries, to ensure their easy access.Teachers should be properly trained and an appropriate suitable assessment system for student achievement should be developed to improve the quality of education and reduce difficulties in assessing student learning outcomes.A global organization for cooperation and harmonization between institutions should be developed to provide quality and impartial education to students around the world.

Conclusion
The online education system is a practical and voluntary choice of many education systems but has now become mandatory for everyone, especially in the higher education system.The review summarizes common teaching issues and possible solutions faced by institutes/ universities in countries classified into different income economy groups during the pandemic.Poor Internet infrastructure, power outages, and limited resources were the main challenges for the countries with the lowest-and middle-income economies, while a lack of technical knowledge of novel virtual tools and simulation techniques or devices was the most common problem for the countries in the high-income group.Recorded video lectures and heterogeneous systems of online and physical education classes are considered effective methods to reduce technology-based challenges.However, online platforms have proven to be a powerful tool for educators, allowing them to continue teaching in times of social isolation and ensure social connectivity while maintaining physical distance.Among these, social media platforms proved to be the best tools for distance learning.ZOOM has been one of the most widely used online platforms in both developed and underdeveloped countries.Although the world is digitizing day by day and innovative technologies are being developed rapidly.It is concluded that basic knowledge is also essential for using these new technologies.Therefore, countries need to invest more in online education training and ensure adequateInternet accessibility and availability, especially in remote areas.Although these available platforms have been successfully adopted as an alternative learning method and the recorded video lectures have received more positive feedback from students, appropriate training facilities, and adequate learning opportunities exist in all regions of the world, especially in remote areas, with availability and affordability of resources should be ensured.

Fig. 5
Fig. 5 Representing the GDPs per capita of different countries.World Bank Report (2019)

Fig. 6
Fig. 6 Percent use of online platforms during the COVID-19 period

Table 1
Description of the articles categorized into teleconferences, webinars, virtual classrooms, and video conferences

S. No. Article type Country Region Number of participants Type of participants Online platforms Description of the adopted strategy Outcomes Strength of evidence
Table 1 (continued) S. No.

Article type Country Region Number of participants Type of participants Online platforms Description of the adopted strategy Outcomes Strength of evidence
Table 1 (continued) S. No.

Article type Country Region Number of participants Type of participants Online platforms Description of the adopted strategy Outcomes Strength of evidence
Table 1 (continued) S. No.

Article type Country Region Number of participants Type of participants Online platforms Description of the adopted strategy Outcomes Strength of evidence
Table 1 (continued) S. No.

Article type Country Region Number of participants Type of participants Online platforms Description of the adopted strategy Outcomes Strength of evidence
Table 1 (continued) S. No.

Table 2
Description of the articles categorized into new applications or design of software S. No.

Table 3
Description of the articles categorized into a social media platform S.

Table 4
Description of the articles categorized into simulation and virtual reality S. No.