The COVID-19 pandemic continues to affect the polio response

December 29, 2021

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A new report highlighted the continuing impact of the COVID-19 pandemic on efforts to eradicate polio.

According to the report recently published in MMWR37 countries reported 44 outbreaks of circulating vaccine-derived poliovirus from January 2020 to June 2021 – almost 90% of them caused by type 2 poliovirus. The outbreaks resulted in 1,335 paralyzed children.

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In 2016, more than 150 countries switched from using a trivalent oral polio vaccine to using a bivalent vaccine containing only types 1 and 3 after the extinction of the wild-type 2 strain. Since the switch, a monovalent type 2 poliovirus vaccine has been used to respond to vaccine-derived polio outbreaks.

In November 2020, the WHO issued a list of emergency uses for a new type 2 oral poliovirus vaccine that was developed to be more genetically stable than the other vaccine, but supply has been limited “due to delays in production due to COVID 19 pandemic and bigger than expected [vaccine] Spending,” Mary M. Alleman, Ph.D., an epidemiologist for the CDC’s Global Immunization Division, wrote.

We spoke to Alleman about disturbances caused by the pandemic, which the authors said may have resulted in an undercount of polio cases and delayed the detection of outbreaks.

Healio: Does COVID-19 Still Affect Eradication Activities?

Alleman: The COVID-19 pandemic has compromised health systems and limited access to vital treatments and public health interventions, such as vaccine-preventable disease surveillance and vaccine administration.

The 4-month suspension of polio vaccination campaigns in early 2020 in more than 30 countries to protect communities and staff from COVID-19, combined with related disorders of routine vaccination, led to tens of thousands of children missing polio vaccination and contributing to the spread of circulating vaccine-derived poliovirus type 2 (cVDPV2s), mainly in the WHO African region. The pandemic has also diverted resources and personnel from poliovirus surveillance.

Despite setbacks, the Global Polio Eradication Initiative (GPEI) has worked with all countries with active wild or circulating vaccine-derived poliovirus outbreaks to resume polio immunization activities and regain lost ground. GPEI has adapted to the challenges of operating during the COVID-19 pandemic by updating monitoring strategies, developing information dashboards and innovative approaches to ensure rapid arrival of fecal and environmental samples to laboratories in the Global Polio Laboratory Network. GPEI supports poliovirus monitoring to detect and monitor the development of poliovirus outbreaks around the world and supports timely vaccination responses to stop outbreaks. Following the early suspension in 2020, the implementation of polio campaigns gradually resumed beginning in the third quarter of 2020 on a country-by-country basis.

Healio: Has the global eradication goal been set further back?

Alleman: In May, GPEI launched an updated 5-year strategy until 2026, changing its approach to overcoming remaining obstacles, including setbacks from the COVID-19 pandemic, to help strengthen immunization systems in the affected countries and deliver and maintain a polio-free world.

The strategy focuses on addressing an emergency, while generating greater accountability and ownership from the country’s governments to certify the eradication of wild-type poliovirus type 1 by 2026 and to discontinue cVDPV2 transmission by the end of 2023.

Healio: Is there a shortage of vaccine?

Alleman: Due to high levels of demand for the new oral poliovirus type 2 vaccine (nOPV2) as well as the negative effects of COVID-19 on its production, the supply of the new vaccine will be limited in the short term. Distribution will be governed by a GPEI priority framework while GPEI works to increase supply.

Due to the public health emergency posed by cVDPV2 outbreaks, it is crucial that countries prioritize high-quality immediate outbreak responses. The recommendation of the Strategic Advisory Group of Experts on Immunization, the WHO Director – General’s Emergency Committee on International Health Regulations on the Spread of Poliovirus as a Public Health Emergency of International Concern, and the GPEI Independent Monitoring Board is that countries should launch rapid response response it is Sabin (mOPV2) or the new vaccine.

In situations where there is co-circulation of poliovirus serotypes, or where there are cVDPV1 / cVDPV3 outbreaks, trivalent oral polio vaccine (tOPV) or bivalent oral polio vaccine (bOPV) may be the more appropriate vaccine choice.

There is no shortage of mOPV2, bOPV or tOPV.

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