Diphtheria-tetanus-pertussis vaccine(Finlay Institute)

In the context of polio eradication efforts, accurate assessment of vaccination programme effectiveness is essential to public health planning and decision making. Such assessments are often based on zero-dose children, estimated using the number of children who did not receive the first dose of the Diphtheria-Tetanus-Pertussis containing vaccine as a proxy. Our study introduces a novel approach to directly estimate the number of children susceptible to poliovirus type 2 (PV2) and uses this approach to provide district-level estimates for South Africa of susceptible children born between 2017 and 2022. We used district-level data on annual doses of inactivated poliovirus vaccine (IPV) administered, live births, and population sizes, from 2017 through 2022. We imputed missing vaccination data, implemented flexible assumptions regarding dose distribution in the eligible population, and used estimated efficacy values for one, two, three, and four doses of IPV, to compute the number of susceptible and immune children by birth year. We validated our approach by comparing an intermediary output with zero-dose children (ZDC) estimated using data reported by WHO/UNICEF Estimates of National Immunization Coverage (WUENIC). Our results indicate high heterogeneity in susceptibility to PV2 across South Africa's 52 districts as of the end of 2022. In children under 5 years, PV2 susceptibility ranged from approximately 30 % in districts including Xhariep (31.9 %), Ekurhuleni (30.1 %), and Central Karoo (29.8 %), to less than 4 % in Sarah Baartman (1.9 %), Buffalo City (2.1 %), and eThekwini (3.2 %). Our susceptibility estimates were consistently higher than ZDC over the timeframe. We estimated that ZDC decreased nationally from 155,168 (152,737-158,523) in 2017 to 108,593 in 2021, and increased to 127,102 in 2022, a trend consistent with ZDC derived from data reported by WUENIC. While our approach provides a more comprehensive profile of PV2 susceptibility, our susceptibility and ZDC estimates generally agree in the ranking of districts according to risk.

Respiratory syncytial virus (RSV) fusion protein stabilized in the prefusion conformation (RSVPreF3) was under investigation as a maternal vaccine.

This phase 2, randomized, placebo-controlled, single-dose, multicenter study enrolled healthy, nonpregnant women, randomized 1:1:1:1:1 to 5 parallel groups studying RSVPreF3 (60 or 120 µg) coadministered with diphtheria, tetanus, and acellular pertussis vaccine (dTpa) or placebo, and dTpa coadministered with placebo. Safety and humoral immune responses were assessed. An extension phase also assessed a RSVPreF3 120 μg vaccination 12–18 months after first vaccination.

The safety profile of RSVPreF3 was unaffected by dose or dTpa coadministration. Solicited and unsolicited adverse events (AEs) were evenly distributed across study groups. Injection-site pain was higher following the second vaccination versus the first vaccination. Medically attended AEs were rare (<5% overall). Both RSVPreF3 dose levels (alone and with dTpa) were immunogenic, increasing levels of RSV-A neutralizing antibody ≥8-fold and anti-RSVPreF3 IgG antibody ≥11-fold at 1 month postvaccination, which persisted at 12–18 months postvaccination; modest 2-fold increases were observed with a second RSVPreF3 vaccination.

This study indicates RSVPreF3 coadministration with dTpa induces robust immune responses and is well tolerated, regardless of the RSVPreF3 dose level used.

NCT04138056.