Impact of COVID-19 Pandemic on Global Poliovirus Surveillance.

On January 30, 2020, the World Health Organization (WHO) declared coronavirus disease 2019 (COVID-19) a Public Health Emergency of International Concern (1). On March 24, 2020, the Global Polio Eradication Initiative (GPEI) suspended all polio supplementary immunization activities and recommended the continuation of polio surveillance (2). In April 2020, GPEI shared revised polio surveillance guidelines in the context of the COVID-19 pandemic, which focused on reducing the risk for transmission of SARS-CoV-2, the virus that causes COVID-19, to health care workers and communities by modifying activities that required person-to-person contact, improving hand hygiene and personal protective equipment use practices, and overcoming challenges related to movement restrictions, while continuing essential polio surveillance functions (3). GPEI assessed the impact of the COVID-19 pandemic on polio surveillance by comparing data from January to September 2019 to the same period in 2020. Globally, the number of acute flaccid paralysis (AFP) cases reported declined 33% and the mean number of days between the second stool collected and receipt by the laboratory increased by 70%. Continued analysis of AFP case reporting and stool collection is critical to ensure timely detection and response to interruptions of polio surveillance.

Fractional-Dose Inactivated Poliovirus Vaccine Campaign - Sindh Province, Pakistan, 2016.

Following the declaration of eradication of wild poliovirus (WPV) type 2 in September 2015, trivalent oral poliovirus vaccine (tOPV) was withdrawn globally to reduce the risk for type 2 vaccine-derived poliovirus (VDPV2) transmission; all countries implemented a synchronized switch to bivalent OPV (type 1 and 3) in April 2016 (1,2). Any isolation of VDPV2 after the switch is to be treated as a potential public health emergency and might indicate the need for supplementary immunization activities (3,4). On August 9, 2016, VDPV2 was isolated from a sewage sample taken from an environmental surveillance site in Hyderabad, Sindh province, Pakistan. Possible vaccination activities in response to VDPV2 isolation include the use of injectable inactivated polio vaccine (IPV), which poses no risk for vaccine-derived poliovirus transmission. Fractional-dose, intradermal IPV (fIPV), one fifth of the standard intramuscular dose, has been developed to more efficiently manage limited IPV supplies. fIPV has been shown in some studies to be noninferior to full-dose IPV (5,6) and was used successfully in response to a similar detection of a single VDPV2 isolate from sewage in India (7). Injectable fIPV was used for response activities in Hyderabad and three neighboring districts. This report describes the findings of an assessment of preparatory activities and subsequent implementation of the fIPV campaign. Despite achieving high coverage (>80%), several operational challenges were noted. The lessons learned from this campaign could help to guide the planning and implementation of future fIPV vaccination activities.

Impact of the SARS-CoV-2 pandemic on vaccine-preventable disease campaigns.

BACKGROUND: The COVID-19 pandemic has contributed to the widespread disruption of immunization services, including the postponement of mass vaccination campaigns. METHODS: In May 2020, the World Health Organization and partners started monitoring COVID-19-related disruptions to mass vaccination campaigns against cholera, measles, meningitis A, polio, tetanus-diphtheria, typhoid, and yellow fever through the Immunization Repository Campaign Delay Tracker. The authors reviewed the number and target population of reported preventive and outbreak response vaccination campaigns scheduled, postponed, canceled, and reinstated at 4 time points: May 2020, December 2020, May 2021, and December 2021. FINDINGS: Mass vaccination campaigns across all vaccines were disrupted heavily by COVID-19. In May 2020, 105 of 183 (57%) campaigns were postponed or canceled in 57 countries because of COVID-19, with an estimated 796 million postponed or missed vaccine doses. Campaign resumption was observed beginning in July 2020. In December 2021, 77 of 472 (16%) campaigns in 54 countries, mainly in the African Region, were still postponed or canceled because of COVID-19, with about 382 million postponed or missed vaccine doses. INTERPRETATION: There is likely a high risk of vaccine-preventable disease outbreaks across all regions because of an increased number of susceptible persons resulting from the large-scale mass vaccination campaign postponement caused by COVID-19.

Routine immunization coverage in Pakistan: a survey of children under 1 year of age in community-based vaccination areas.

Pakistan is one of two countries in which poliovirus remains endemic. Considering the high number of children born every year, reaching and vaccinating new birth cohorts by improving routine immunization coverage in children <1 year of age is crucial to halting virus transmission. In 2015, a community-based vaccination (CBV) strategy, using local community members to enhance vaccine acceptance and improve routine immunization service delivery, was introduced in areas of Pakistan that have never interrupted poliovirus transmission. In order to assess progress towards improving routine immunization, we performed house-to-house immunization surveys across ten CBV areas in 2017 and 2018. In each household, we determined age-appropriate routine antigen coverage for children <1 year of age based on vaccination card and caregiver recall. We surveyed 5,499 and 5,264 children in 2017 and 2018, respectively. Overall, coverage of inactivated poliovirus vaccine (IPV) at 14 weeks of age was 32% in 2017 and 39% in 2018 based on vaccination card and recall. Across the surveyed areas, coverage ranged from 7% in Killa Abdullah to 61% in Peshawar in 2018. Oral poliovirus vaccination coverage decreased with successive vaccination visits, ranging from 66% for the birth dose to 42% for the 14-week dose in 2018. No area reached the target of 80% coverage for any routine antigen. Our findings highlight the need for concerted efforts to improve routine immunization coverage in these critical areas of wild poliovirus transmission.