Re‐emergence of polio in Pakistan: Can the nation achieve the WPV1 eradication goal?

Abstract

Background and Aims

Poliomyelitis is an acute neurologic condition that causes muscle weakness, permanent flaccid paralysis, and even death. The world has seen a drastic fall in the number of poliovirus cases owing to effective immunization programs and preventive measures. Pakistan and Afghanistan still remain the two endemic countries for poliovirus, particularly, the WPV1 strain. Global Polio Eradication Initiative (GPEI) has set a target to eradicate all WPV1 cases by the end of 2023. However, the re‐emergence of WPV1 cases has posed a serious setback for the achievement of this target. This article aims to discuss the public health challenges that contribute to resurgence of poliovirus cases.

Methods

A comprehensive literature search was conducted using various databases including Cochrane, Google Scholar, PubMed, Science Direct, MEDLINE. Only articles written in English were considered. All the articles reporting the incidence of poliovirus and WPV1 cases in Pakistan, surveillance data and global context of poliovirus outbreak were evaluated to write this correspondence. In addition, references from the selected articles were also examined to ensure a comprehensive review of the literature.

Results

This article highlights the factors contributing to the re‐emergence of WPV1 cases in Pakistan. Low vaccine coverage, attacks on frontline polio health workers, misinformation, and reluctance to vaccine acceptance pose a daunting challenge for polio eradication. Further, gaps in AFP surveillance and sensitivity may underestimate the true extent of the emerging genetic clusters. The Covid‐19 pandemic and subsequent flooding in the affected area have further worsened the underdeveloped public health infrastructure.

Conclusion

Despite the challenges, the country has observed a significant decline in the number of cases in the past 2 years. It is high time to capitalize on the decrease in WPV1 cases by intensifying the efforts to mitigate and limit the spread of the disease.

Poliomyelitis, commonly referred to as polio, is an acute neurologic condition that causes muscle weakness, permanent flaccid paralysis, and even death. It is caused by a single‐stranded RNA virus from the Picornaviridae family belonging to the Enterovirus genus. It spreads via the oral‐fecal pathway and affects Children under 5‐year‐old. There is no treatment available for this disorder but it can be prevented through vaccination. ¹ Although eradicated globally, Pakistan and Afghanistan are two endemic nations for polio, particularly wild poliovirus type 1 (WPV1), and a potential source of infection for global transmission.

In Pakistan polio eradication program was officially launched in 1994 but despite more than 100 rounds of vaccination conducted over the past 10 years, poliovirus is still endemic in the country. In 2017, there were 8 WPV1 cases reported, followed by 12 cases in 2018, 147 in 2019, 84 cases in 2020, and 1 and 20 cases in 2021 and 2022 respectively. ² , ³ Global Polio Eradication Initiative (GPEI) has set a target to eradicate all WPV1 cases by the end of 2023. However, the re‐emergence of 6 new cases of WPV1 as of November, 2023 in Pakistan comprising of 3 cases in the Bannu district of KPK, 1 in Orakzai, and 2 in Karachi, ³ along with the identification of about 92 WPV1 positive environmental samples in KPK and other provinces in 2023 suggests a wider WPV1 circulation and has jeopardized the main objective. ⁴ Although circulating vaccine‐derived poliovirus (cVDPV) has caused multiple outbreaks in the past, there has been no cVDPV outbreak reported after 2021 in Pakistan. Nevertheless, the continuous emergence of WPV1 cases poses a significant challenge for the fragile healthcare system of the country.

KPK has been one of the challenging sites to eradicate poliovirus. It has been reported that about 400,000–500,000 children are repeatedly missed during nationwide polio supplementary immunization activities (SIAs), leading to inadequate vaccine coverage of <80% in Sindh, Punjab, and KPK districts. The unvaccinated individuals contribute to the majority of the cases as evidenced by the recorded cases during January 2021 to July 2022, when 87% of unvaccinated individuals contracted WPV1, thereby posing a significant challenge for polio eradication. ⁵ In a recent study conducted by Khan et al in 2023, the proportion of immunized children in Peshawar was 80.7% and below 50% in other districts of Pakistan, making up only 60% of the children immunized with three doses of OPV and one dose of IPV. In addition to the low vaccine coverage, significantly high dropout rate exceeding more than 10% has been observed in several districts of the country. ⁶ Trends in the polio vaccination campaign in Pakistan have been impacted by a number of variables, such as spread of misinformation and geopolitical concerns, as evidenced by the recent boycott to immunization campaigns in several districts of Pakistan until the fulfillment of economic and healthcare demands. ⁷ These elements have affected immunization efforts' consistency, resulting in vaccine coverage gaps which eventually lead to the resurgence of polio cases in Pakistan. Thus, due to gaps in vaccine coverage, there may be vulnerable population pockets where the virus can still propagate and spread among the unvaccinated individuals, thereby posing a barrier to global eradication efforts.

The massive movement of subpopulations of unimmunized individuals between Pakistan and Afghanistan facilitates crossborder transmission, which further exacerbates the situation. It has been reported that Afghanistan has a large proportion of unvaccinated children and the predominant spread of WPV1 lineages in Afghanistan in 2022 has been subsequently observed in Pakistan in 2023, thereby presenting a lingering threat for the risk of cross‐border transmission and international spread. ⁸ The identification of additional genetic clusters from environmental samples in KPK strongly indicates gaps in AFP surveillance and sensitivity. Additionally, low efficacy and growing resistance against OPV has contributed to vaccine hesitancy, leading to disproportionate suspicion for polio health workers who are targeted with violence and assaults. Illiteracy, rumors, false religious beliefs, and the distorted law and order situation have led to numerous attacks on polio vaccinators and the security personnels accompanying polio teams causing the death of over more 200 polio workers since 2012. ⁹ Most number of attacks on polio teams were reported in Quetta, Karachi and different areas of KPK especially those located near Pak‐Afghan border, an endemic area for poliovirus, thereby making it a grave concern. Lack of education and ignorance about the disease and its prevention, and poor sanitation among the populace in Southern districts of Khyber Pakhtunkhwa Province also contributes to the failure of the polio eradication program, which is further compromised by various social, cultural, and religious factors, reluctant parents, and poor program administration. The religious factor involved as obstacle in vaccine coverage is attributed to the fact that some people have a firm belief that there are some ingredients in the vaccine which are prohibited by their religion, they deem it “haram” and hence, refuse to vaccinate their children. Additionally, misinformation and rumors also lead to a decline in vaccine acceptance among the general population. ¹⁰ The emergence of Covid‐19 suspended door‐to‐door vaccination and subsequently flooding in many places in Pakistan has complicated vaccination and surveillance in the affected regions, perhaps causing serious setbacks to the polio eradication initiative.

The nation's health administration should assume full responsibility for improving the underdeveloped healthcare infrastructure. Strategic and prompt management will be achievable if the state increases its vigilance in the surveillance of emerging genetic clusters and creates extensive disease monitoring regulations. Integrating polio efforts with other preventive health services, particularly child health, nutrition, and routine immunization, may alleviate community resistance and broaden the program's reach. Furthermore, it is essential to ensure full security for frontline polio health workers to guard their safety. Considering significant vaccine hesitancy among the people, it is crucial to implement advocacy, awareness campaigns in communities to educate the public on the significance of poliovirus vaccinations before initiating vaccination programs, especially in high‐risk areas. By making social media more available in these off‐the grid locations, we can utilize it as a powerful weapon to dispel misconceptions and alter public attitudes toward the vaccine. It will ensure a wider public participation in immunization campaigns and can also help to decrease the marked ratio of vaccination drop‐outs. The healthcare members should be updated with latest and authentic information to help counter the arguments against vaccine effectively. Furthermore, Nigeria used a GPS tracking system of immunization teams to enhance the vaccination activities especially in areas with minimal vaccination coverage. ¹¹ It is critical to implement systematic tracking of vaccinated and persistently missed children, specifically in highly mobile families, following SIAs. Every child must be properly verified as being vaccinated, not just by a mark on the little finger, which is also susceptible to forgery. Furthermore, it is critical to enhance water safety and improve the quality of drinking water as well as maintenance of waste‐water system. Similar strategies were implemented by Yemen which led to considerable decline in the incidence of poliovirus cases. ¹² The government should collaborate with WHO, and UNICEF for successful attainment of these goals.

Despite numerous obstacles, several polio eradication initiatives in Pakistan have made a remarkable progress. The country has collaborated with WHO, UNICEF, and GPEI in efforts to control and mitigate the number of cases. This is attributed mainly to the decreased number of cases emerging in the year 2023 as compared to previous years, and majority of the cases have been restricted to a district in KPK. Large numbers of polio workers, strict surveillance strategies, and multiple rounds of vaccinations have greatly helped to decrease the pool of unvaccinated individuals in the country. ¹³ As of August 2023, approximately 9.45 million children have been vaccinated in the biphasal vaccination drive conducted across 65 districts. ¹⁴ The aforementioned context demonstrated the effectiveness of vaccination campaigns and other antipolio initiatives. Nevertheless, obstacles including vaccination scepticism, accessibility problems to some locations, and security concerns in some areas continue to exist and impede total eradication efforts.

If we fail to achieve polio eradication, the consequences can be significant both nationally and globally. Nationally, the persistence of polio can lead to outbreaks and the reemergence of the disease, causing severe disabilities and even death among children. It can also strain healthcare systems and hinder overall development efforts. Globally, the failure to eradicate polio can result in the spread of the disease to other countries, reversing the progress made so far. This would pose a risk to populations that have already eliminated polio and require continued resources and efforts to control the disease. It's crucial that we stay committed to achieving polio eradication to protect future generations and ensure a polio‐free world.

The broader implications of the polio eradication issue are significant. First, achieving polio eradication would be a major milestone in public health, showcasing the power of global collaboration and vaccination efforts. It would also serve as a blueprint for tackling other infectious diseases. Additionally, eradicating polio would save billions of dollars in healthcare costs and enable resources to be redirected toward other pressing health issues. Lastly, it would reinforce the importance of routine immunization and strengthen healthcare systems, benefiting communities beyond just polio prevention.

In conclusion, the re‐emergence of the WPV1 case in Pakistan is a wake‐up call for strengthening the efforts for polio eradication. There is a high risk of a rise in polio cases in Pakistan if prompt measures are not taken to improve vaccination coverage and surveillance. Despite the challenges, the country has observed a significant decline in the number of cases in the past 2 years. It is high time to capitalize on the decrease in WPV1 cases by intensifying the efforts to mitigate and limit the spread of the disease. This window of opportunity should be utilized effectively for the eradication of the WPV1 strain, not only nationwide but also on a global scale.

AUTHOR CONTRIBUTIONS

Aqib Faizan: Conceptualization; writing—original draft. Tooba Rehman: Conceptualization; writing—original draft. Sanila Mughal: Writing—review & editing.

CONFLICT OF INTEREST STATEMENT

The authors declare no conflict of interest.

TRANSPARENCY STATEMENT

The lead author affirms that this manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned (and, if relevant, registered) have been explained.

Faizan A, Rehman T, Mughal S. Re‐emergence of polio in Pakistan: can the nation achieve the WPV1 eradication goal? Health Sci Rep. 2024;7:e1862. 10.1002/hsr2.1862

DATA AVAILABILITY STATEMENT

Data sharing not applicable to this article as no data sets were generated or analyzed during the current study.