1 INTRODUCTION

Polio is a well-known detrimental disease, predominant in children and infectious to the level of causing permanent paralysis to multiple body organs. The virus can lead to death by immobilizing the breathing muscles. Polio can be prevented through proper vaccination. Massive efforts have been performed to eradicate the poliovirus since the discovery of the first polio epidemic in 1894 to the licensing of the Sabin vaccine and its application from 1963 onwards. Yet to date, no effective medication options have been developed for paralytic polio disease.¹

With successful vaccination efforts, high-income (HIC), and educated countries have succeeded in eradicating polio viral cases to a great extent. However, recently some single polio outbreaks have been notified in some HICs. Reports regarding paralytic polio cases have been identified from the cities of London, New York, and Jerusalem.² Additionally, an active polio case has been identified in the UK after 40 years.³ Some inactive cases of poliovirus have also been identified in various European countries (Table 1). Moreover the prevalent war situation in Ukraine, Yemen, Syria, and other Middle Eastern countries, with the least focus on healthcare measures, clearly shows a disregard for the polio threat. A lower vaccination rate owing to the disruption caused by war coupled with the pandemic and increased emigration can lead to polio spreading to other countries.³

Besides the threats in HICs that get more attention, the actual problem rests with the challenges presented by the lower-middle-income (LMI) nations, where the wild poliovirus still remains prevalent in its active form. Active cases have been identified in Pakistan and Afghanistan.⁴ This situation requires a timely response to avoid the cross-border spread of poliovirus. For this cause, a response campaign was generated in form of the “Global Polio Eradication Initiative” (GPEI) in 1988 to deal with the burden of global polio cases. A massive vaccination campaign was successful till 2000. However, a delay has been observed in the accomplishment of its goal due to the prevailing weaknesses of healthcare systems in LMICs.⁵

The campaign has acquired a multipronged strategy. Its mission is to eradicate the transmission of wild polioviruses by oral polio vaccine (OPV) to bring about the destruction of, and immunization against all types of poliovirus. GPEI has been working on the public–private-partnership model to bring mutual efforts of other social and healthcare organizations including WHO, UNICEF, CDC, and some other names such as Rotary International and the Bill and Melinda Gates Foundation to fight against Polio.⁶ Thus in light of prevalent poliovirus cases, the resurgence of new inactive strains throughout the world and the efforts carried out against this scenario are the main focus of this paper. With the aforementioned organizations on board, combined efforts are being carried out to prevent the rare incidence of poliomyelitis. Hope is there, and with timely planning of vaccination drives the focus is being kept on the eradication of polio along with Coronavirus pandemic.⁷

2 METHODOLOGY

This short communication has been conducted via a search strategy based upon the inclusion of only the most recent reports of polio cases identified in different regions of the world during the past 12 months (August 2021 to August 2022). Data were collected via a systematic literature search through various online search engines including Google Scholar, PubMed, NIH (National Library of Medicine), and Web of Science. Additionally, data relevant to reported cases have been derived from the official websites of the GPEI, CDC, UNICEF, and WHO to include only the approved data. It should be noted that most focus has been kept on the viral incidence rates that have been recorded in the past 12 months. Moreover, only the studies of English language origin have been made part of this literature.

3 RESULTS

Extraordinary efforts have been made by healthcare organizations for eliminating the poliovirus from healthcare systems. As a result, the world has acquired success in reducing paralytic incidence by up to 99.99%.⁸ However, the surge of noninfectious polio cases around the world calls for action to take mitigation measures against paralytic forms.⁹ A sustainable approach is, therefore, being adopted throughout the world especially in affected regions to ensure a 100% global population immunization. Such a measure will promote the eradication of poliomyelitis, simultaneously with immunization awareness against other preventable viral diseases such as coronavirus.⁷

The prevalence of remaining viral cases in LMICs like Pakistan and Afghanistan truly indicates that viral infections are still there, owing to poor social practices and a lack of cultural and religious understanding.^{10, 11} Some other reasons for a gap in full immunization may include those pertaining to vaccine hesitancy, foreign conspiracy theories, wrong information spread regarding vaccination, and the global displacement caused by the healthcare disruption in the Coronavirus pandemic period.⁷

From 1988 to date GPEI has been successful in the eradication of wild poliovirus WPV Type 2 and 3 cases up to 99.99%.¹² Afghanistan and Pakistan were previously regarded as the only two countries where cases of WPV Type 1 had been notified. However, most recent data suggest that some cases have also been identified in Mozambique and Malawi (Table 1). Pakistan and Afghanistan recorded 140 cases of WPV1 in the year 2020 and 5 cases in 2021.¹² Similarly, vaccine-derived poliovirus cases have also been reported around the globe. According to the official data provided by GPEI, the total number of WPV1 cases as of August 2022 was 26 in total.¹³ The latest onset of cVDPV1 cases has been reported in different countries while cVDPV2 cases have shown an increase in infected areas, with approximately 608 viral variant cases reported. One case of cVDPV3 has been reported in Israel.¹³

A list of countries, including Benin, Cameroon, The Central African Republic, Congo (Republic of), Côte d'Ivoire, Ethiopia, Eritrea, Gambia, Guinea, Guinea-Bissau, Liberia, Mauritania, Senegal, Sierra Leone, South Sudan, Uganda, has reported some cases in the past year, but these countries have shown no recent surges of cVDPV2 viruses in 2022. Other countries in which positive cases have been reported are briefly summarized in Table 1. It should be kept in mind that the table contains only the cases from the past 12 months, and no previous cases are recorded.¹³

Although GPEI is working on its strategic plan of ending paralytic cases of WPV1 by the end of 2023, with the rising incidence of cVDPV and WPV-1 cases, the threat of paralytic polio cases in children remains concerning.⁷ For this reason, efforts are being directed toward two types of countries that have been divided under categories of “outbreak countries” and “endemic countries”; a brief account of these countries has been discussed below.¹³

The first group is labeled as “Outbreak Countries.” This group includes countries that are not experiencing indigenous wild polio cases. However, these countries remain under the impact of infections driven by wild or vaccine-derived poliovirus cases. These infections may be caused by the circulation of polioviruses brought from other countries, especially the endemic ones. Many countries in Africa, the Eastern Mediterranean, and Europe are included in this category. For this reason, a special focus is kept on these countries and efforts are underway to completely eradicate polio cases in coordination with the guidelines for international outbreak response.¹⁴

The second group has been labeled as “Endemic Countries.” This category includes countries where the transmission of wild poliovirus has never stopped completely, though short periods of pauses have been observed in the past. Moreover, these countries keep on inculcating outbreaks of circulating vaccine-derived poliovirus cases. The two most important countries in this regard are Afghanistan and Pakistan. According to global statistics, the total incidence of wild-type poliovirus in the last 5 years has been reported at around 396 (100), out of which 265 (~67) have been reported in Pakistan and 129 (32.5) cases have been reported in Afghanistan. Out of these 385 cases, only 18 (14 in Pakistan and 4 in Afghanistan) have been reported in the last 12 months.^{7, 13}

Polio vaccination rates of 2020 indicate that vaccination coverage in Afghanistan and Pakistan lies between 65% and 85%.⁷ But the resurging cases indicate that this vaccination coverage is substantially lower than required and a 100% vaccination drive is needed to eradicate the chances of polio directly from these endemic regions. Besides the two aforementioned categories of countries, all other countries have been accounted for under the WHO-certified polio-free world regions. Six world regions are included in this division: these are Africa, the Americas, Eastern Mediterranean, Europe, South-East Asia, and Western Pacific. The three distinctions that are related to these regions include (a) no recorded track for the wild indigenous polio cases for at least the last 3 years, (b) the evidential working of a reliable surveillance system, and (c) built-in capacity for detection and response to the imported poliovirus cases¹⁵

4 DISCUSSION

Until no polio cases are reported in endemic countries, all other countries especially the aforementioned “outbreak countries,” with weak healthcare systems and having trade and travel links with endemic countries, will remain at risk of contracting paralytic viruses. Therefore, for the complete elimination of poliovirus cases efforts on the level of immunization campaigns, vaccination coverage, and surveillance reports are required to dictate mitigation and adaptation measures against poliovirus.

Political and military conflicts in outbreak countries have been hurdles on the way to polio eradication teams in the past. Resultantly, the incidence rates of paralytic cases caused by cVDPV2 are increasing especially in Africa and Asia.⁹ Thus to deal with the sustaining trends of polio cases, GPEI is continuously tracking changes and adjustment channels to cope with the needs of emerging cases. They are taking measures to make the program more sustainable to tackle the prevailing cases and to deal with the chance emergence of new wild cases of paralytic polio.²

Moreover, polio eradication teams in affected regions are now largely focused on curtailing poor social behavior against vaccination. Governments’ representative authorities, local influencers, and social media outlets are also playing positive roles in promoting awareness and trust between the community and healthcare workers.¹¹ Nevertheless, these combined efforts have brought a marked reduction in poliovirus transmission rates, especially after the start of the coronavirus pandemic. The major reason behind this progress could be linked to enhanced awareness among the public and renewed national commitments to vaccination campaigns.¹⁵ This highlights that the efforts driven by foreign organizations like GPEI and UNICEF are not enough for endemic countries and an on-ground effort based on each countries' healthcare system improvement is needed to deal with the immunization problem at the grassroots level.¹⁶

The past 3 years have presented major challenges to healthcare owing to the coronavirus pandemic. Besides affecting individual health, the provision of polio vaccinations and resources for the implementation of polio eradication programs have also been largely compromised. To tackle Covid-19, GPEI and WHO largely suspended house-to-house supplementary immunization activities (SIAs) for polio at the beginning of the pandemic. Specific guidelines have been in implementation since the pandemic outbreak.¹⁷ The short-term impact of the pandemic on polio resurgence can be seen in the form of recent outbreaks in polio-free countries while the longer-term impact of polio and coronavirus epidemiology still needs to be determined. Participation of communities is needed to curtail global health problems.

To meet the goals of the GPEI strategic plan (2022–2026) of ending poliovirus cases by 2023, it is imperative to take proactive mitigation measures and take on adaptation measures against polio resurgence.¹³ Any stumbling rock in efforts to eradicate WPV1 and cVDPV transmission could pose a risk to poliovirus export from endemic countries to other regions in the world. It is an important step to fully secure the containment of poliovirus owing to its resistive pathogenic nature. If care is not taken, even a single infectious virus can lead to a drastic resurgence of the disease in susceptible populations. The focus should be diverted from meeting the deadlines of GPEI to counterproductive measures in research and development because there are still some shortcomings attached to the existing polio vaccines IPV and OPV. Nevertheless, overcoming these shortcomings and developing new, improved, less expensive, and more efficient vaccines could bring a better, long-term solution to the polio-endemic.¹⁸

5 RECOMMENDATIONS

To tackle the compromised polio eradication campaign and to turn the pandemic gap into an opportunity, a combined, rapid, coordinated, and widespread effort is required from all the pillars of government in affected countries. Lessons learned by GPEI and EPI partner countries during the past 3 years should be directed toward enhancing public health initiatives. Polio surveillance should be kept on record especially in Pakistan and Afghanistan with wild-type poliovirus records. The governments in affected regions should work with media, administration, and healthcare officials to devise a proper strategy against COVID and polio outbreaks with operational modifications.19

Moreover, regions, where upgraded polio vaccines have arrived, should completely phase out conventional OPV, while in regions where the reach of the new vaccine is limited, vaccination campaigns should continuously use OPV-based vaccines. These measures can help to establish population immunity where the virus will no longer be transmitted across the populace and will gradually disappear.⁴ Furthermore, a community response should be introduced via a participatory approach to spread awareness and response measures for the polio eradication program. Political, social, and cultural hurdles can only be curtailed through proper awareness in the community. This could be done by enhancing public healthcare facilities through continuous commitment, mitigation measures, advanced planning, and complying with the implications of the GPEI mode of action.

6 CONCLUSION

Scientific observations and experiments have indicated that the permanent and rapid elimination of the poliovirus threat cannot be guaranteed, as proposed by the deadlines of GPEI. Therefore the core of the recommendation is to maintain the highest possible immunization rates throughout the world indefinitely, like that of the smallpox virus model. Moreover, these efforts of polio eradication must be coupled with a global immunization program for coronavirus. The governments of the outbreak and endemic countries, especially those with active wild polio cases, should take part in improvising vaccination drives. Any failure and lack of intention to eradicate polio in endemic countries will further the chance of a resurgence of wild-type cases in the world. Therefore, a combined effort from all countries, including government, healthcare organizations, media, and positive collaboration of the local community is of particular importance in this regard.

AUTHOR CONTRIBUTIONS

Shiza Malik designed and performed the research and wrote the paper; Yasir Waheed supervised, analyzed, and reviewed the data.

CONFLICT OF INTEREST

The authors declare no conflict of interest.