Safety of incidental exposure to the novel oral poliovirus vaccine type 2 in pregnancy: A longitudinal observational study in Mozambique, 2022-2023.

Background: To minimize the risk of vaccine-derived poliovirus emergences, the novel oral poliovirus vaccine type 2 (nOPV2), was bioengineered to have increased genetic stability compared to Sabin OPV and recommended for outbreak response Emergency Use Listing by WHO. Although pregnant women are not a target population for this vaccine, a theoretical risk of incidental exposure exists via pharyngeal or faecal shedding from vaccinated children in the household or close community.

Methods: This was an observational study of pregnant women conducted in Nampula (exposed cohort) and Maputo (non-exposed cohort) in Mozambique from August 2022 to June 2023.

Poliovirus serological assay after the cVDPV1 outbreak in Papua New Guinea: a cross-sectional study from 2020 to 2021.

Background: In June 2018, a type 1 circulating vaccine-derived poliovirus (cVDPV1) outbreak was declared in Papua New Guinea (PNG), resulting in a total of 26 paralytic confirmed cases. Eight vaccination campaign rounds with bivalent oral poliovirus vaccine (bOPV) were carried out in response. Prevalence of neutralizing polio antibodies in children was assessed two years after the outbreak response was completed.

Persistence of immunity following a single dose of inactivated poliovirus vaccine: a phase 4, open label, non-randomised clinical trial.

Background: The polio eradication endgame required the withdrawal of Sabin type 2 from the oral poliovirus vaccine and introduction of one or more dose of inactivated poliovirus vaccine (IPV) into routine immunisation schedules. However, the duration of single-dose IPV immunity is unknown. We aimed to address this deficiency.

Two-Year Duration of Immunity of Inactivated Poliovirus Vaccine: A Follow-up Study in Pakistan in 2020.

This was a follow-up study conducted in 2020 assessing changes in levels of type 2 poliovirus-neutralizing antibodies 2 years postimmunization in children who received inactivated poliovirus vaccine (IPV) in Karachi, Pakistan. Unexpectedly, the findings revealed an increase in seroprevalence of type 2 antibodies from 73.1% to 81.

Community-based survey to assess seroprevalence of poliovirus antibodies in far-north Cameroon in 2020.

Background: This study assessed seroprevalence of poliovirus antibodies in children from selected poliovirus high-risk areas of the Far North region of Cameroon which serves to monitor polio immunization program.

Methods: This was a community-based cross-sectional seroprevalence survey involving collection of dried blood specimens (DBS) among children aged 12-59 months (n = 401). Multi-stage cluster sampling using GIS was applied to select the study sample.