To the Editor—Before the emergence of COVID-19, polio was considered to be one of the most challenging infectious diseases of international concern, despite the consistent efforts of the Global Polio Eradication Initiative (GPEI) program to vaccinate every child in the endemic countries, Pakistan and Afghanistan. In June 2021, the GPEI launched a revised and strengthened plan ‘Polio Eradication Strategy 2022–2026: Delivering on a Promise’, replacing the previous plan from 2019 to 2023, to overcome the continuing challenges in polio eradication1.
In the past five years, 67% of the total wild poliovirus type 1 (WPV1) cases were reported from Pakistan, with the remaining 33% from Afghanistan, and all other cases worldwide were due to circulatory vaccine-derived poliovirus2. Unlike routine pediatric vaccination, polio vaccination campaigns have been particularly hampered by conspiracy theories and poor awareness about the lifesaving benefits of vaccines, at least among some parents3. Consequently, lack of vaccination and incomplete vaccination have been the main factors for the emergence of WPV1 and circulatory vaccine-derived poliovirus (cVDPV2) cases in both countries. However, the recent global vaccination drive against COVID-19 has raised public understanding of the need for vaccines in general, including polio vaccine. Although COVID-19 and polio have distinct physiological manifestations, both diseases share the commonality of vaccination as the only preventive measure.
The COVID-19 pandemic is continuously playing havoc with 211.7 million cases and 4.43 million deaths (as of 23 August 2021)4. Although the emergence of different variants of SARS-CoV-2, such as the Delta variant, has challenged control strategies, the WHO-approved vaccines have diminished the drastic situation in terms of mortality and morbidity. As of 23 August 2021, 24.6% of the world population had been fully vaccinated, 32.7% had received at least a single dose and 33.56 million doses are being administered on daily basis5.
However, the pandemic has compromised the fragile and oversaturated healthcare systems in low- and middle-income countries, including the routine pediatric immunization against vaccine-preventable diseases. For example, inadequate vaccination against measles has listed Pakistan and Afghanistan among the top ten countries with the highest measles cases in 20216. According to UNICEF, the temporary suspension of polio vaccination campaigning in both countries in March 2020, to circumvent the potential spread of COVID-19, had left 50 million children unimmunized7. Although the polio vaccination campaign resumed in July 2020, the number of polio cases (WPV1 and cVDPV2) had reached 219 in Pakistan and 364 in Afghanistan by the end of 20208, which accounted for 47.5% of all global polio cases last year.
Nevertheless, the emergence of 9 polio cases (1 WPV1, 8 cVDPV2) in Pakistan and 44 cases (1 WPV1, 43 cVDPV2) in Afghanistan between January and August 20218 indicates a sharp decline, with most of the cases being vaccine-derived. With only two cases of WPV1 in both countries, 2021 is on track to have the lowest toll of polio virus in a decade (Fig. 1). This reduction in polio may be attributed to efficient governmental interventions and improved awareness of vaccination among the general public.
Amidst the fourth wave of COVID-19 and the potential threat of the Delta variant, Pakistan has prioritized polio vaccination campaigns and more than 40 million children have received two doses of the polio vaccine in 20219. By contrast, Afghanistan is struggling to continue their polio vaccination campaigns10; in part due to instability and the changing political dynamics of the country.
Vaccine hesitancy in Pakistan and Afghanistan has been a considerable problem for polio eradication in the past. The widespread coverage and administration of COVID-19 vaccines around the world has increased awareness about the lifesaving effects of vaccines, and this has had an effect on public awareness in polio endemic countries. There remains a need for booster doses of polio vaccines, especially in the tropics. There is also a need to implement GPEI’s “the switch” strategy to phase out the oral polio vaccine in routine immunizations, which may reduce vaccine-derived polio cases by more than 90%. Nevertheless, COVID-19 vaccination centers remain an ideal setting to increase awareness of polio vaccines, to protect the lives of children, and finally move towards eradication.
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WHO. http://www.emro.who.int/afg/afghanistan-news/third-national-polio-immunization-campaign-begins-in-afghanistan.html (accessed 11 August 2021).
The authors declare no competing interests.
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Ali, M., Khan, J., Ahmad, N. et al. COVID-19 vaccination gives hope to eradicate polio. Nat Med 27, 1660–1661 (2021). https://doi.org/10.1038/s41591-021-01518-z