Progress in the Typhoid Conjugate Vaccine Program Rollout Supported by Gavi During the COVID-19 Pandemic and the Path Forward.

Gavi supports countries to introduce typhoid conjugate vaccine (TCV) with catch-up campaigns. Available TCVs are highly efficacious, equity-focused, and critical to curbing the expansion of antimicrobial resistance. Four Gavi-supported countries have introduced TCVs since 2018.

Evolving epidemiology of poliovirus serotype 2 following withdrawal of the serotype 2 oral poliovirus vaccine.

Although there have been no cases of serotype 2 wild poliovirus for more than 20 years, transmission of serotype 2 vaccine-derived poliovirus (VDPV2) and associated paralytic cases in several continents represent a threat to eradication. The withdrawal of the serotype 2 component of oral poliovirus vaccine (OPV2) was implemented in April 2016 to stop VDPV2 emergence and secure eradication of all serotype 2 poliovirus. Globally, children born after this date have limited immunity to prevent transmission.

The effect of mass vaccination campaigns against polio on the utilization of routine immunization services: A regression discontinuity design.

Background: In most low and middle-income countries (LMIC), vaccines are primarily distributed by routine immunization services (RI) at health facilities. Additional opportunities for vaccination are also provided through mass vaccination campaigns, conducted periodically as part of disease-specific initiatives. It is unclear whether these campaigns are detrimental to RI services, or wether they may stimulate the utilization of RI.

Polio supplementary immunization activities and equity in access to vaccination: evidence from the demographic and health surveys.

Every year, large numbers of children are vaccinated against polio during supplementary immunization activities (SIAs). Such SIAs have contributed to the >99% decline in the incidence of poliovirus cases since the beginning of the Global Polio Eradication Initiative. It is not clear, however, how much they have also contributed to reducing poverty-related inequalities in access to oral polio vaccine (OPV).