How effective is the BNT162b2 mRNA vaccine against SARS-CoV-2 transmission and infection? A national programme analysis in Monaco, July 2021 to September 2022.

We quantified SARS-CoV-2 dynamics in different community settings and the direct and indirect effect of the BNT162b2 mRNA vaccine in Monaco for different variants of concern (VOC). Between July 2021 and September 2022, we prospectively investigated 20,443 contacts from 6320 index cases using data from the Monaco COVID-19 Public Health Programme. We calculated secondary attack rates (SARs) in households (n = 13,877), schools (n = 2508) and occupational (n = 6499) settings. We used binomial regression with a complementary log-log link function to measure adjusted hazard ratios (aHR) and vaccine effectiveness (aVE) for index cases to infect contacts and contacts to be infected in households. In households, the SAR was 55% (95% CI 54-57) and 50% (48-51) among unvaccinated and vaccinated contacts, respectively. The SAR was 32% (28-36) and 12% (10-13) in workplaces, and 7% (6-9) and 6% (3-10) in schools, among unvaccinated and vaccinated contacts respectively. In household, the aHR was lower in contacts than in index cases (aHR 0.68 [0.55-0.83] and 0.93 [0.74-1.1] for delta; aHR 0.73 [0.66-0.81] and 0.89 [0.80-0.99] for omicron BA.1&2, respectively). Vaccination had no significant effect on either direct or indirect aVE for omicron BA.4&5. The direct aVE in contacts was 32% (17, 45) and 27% (19, 34), and for index cases the indirect aVE was 7% (- 17, 26) and 11% (1, 20) for delta and omicron BA.1&2, respectively. The greatest aVE was in contacts with a previous SARS-CoV-2 infection and a single vaccine dose during the omicron BA.1&2 period (45% [27, 59]), while the lowest were found in contacts with either three vaccine doses (aVE - 24% [- 63, 6]) or one single dose and a previous SARS-CoV-2 infection (aVE - 36% [- 198, 38]) during the omicron BA.4&5 period. Protection conferred by the BNT162b2 mRNA vaccine against transmission and infection was low for delta and omicron BA.1&2, regardless of the number of vaccine doses and previous SARS-CoV-2 infection. There was no significant vaccine effect for omicron BA.4&5. Health authorities carrying out vaccination campaigns should bear in mind that the current generation of COVID-19 vaccines may not represent an effective tool in protecting individuals from either transmitting or acquiring SARS-CoV-2 infection.

Althaus T ，Overton CE ，Devaux I ，House T ，Lapouze A ，Troel A ，Vanzo B ，Laroche M ，Bordero A ，Jorgensen P ，Pebody R ，Voiglio EJ ... -  《BMC Medicine》

BNT162b2 vaccine protection against omicron and effect of previous infection variant and vaccination sequence among children and adolescents in Singapore: a population-based cohort study.

Yung CF ，Pang D ，Kam KQ ，Lye DC ，Ong B ，Chong CY ，Tan KB ... -  《-》

Effectiveness of mRNA booster doses in preventing infections and hospitalizations due to SARS-CoV-2 and its dominant variant over time in Valencian healthcare workers, Spain.

This study aimed to evaluate the effectiveness of SARS-CoV-2 mRNA vaccines in preventing infection and hospitalization among healthcare workers (HCWs) in the Valencian Community (Spain), considering vaccination timing, dose number, and predominant variant. A test-negative case-control design estimated vaccine effectiveness against symptomatic disease and hospitalization due to SARS-CoV-2. HCWs who underwent PCR or antigen testing for SARS-CoV-2 from January 2021 to March 2022 were included. Cases had a positive diagnostic test, while controls had negative tests. Adjusted vaccine effectiveness (aVE) was calculated using the formula: aVE = (1 - Odds ratio) × 100. During the Delta variant's predominance, aVE against infection within 12-120 days post-second dose was 64.8 % (BNT162b2) and 59.4 % (mRNA-1273), declining to 21.2 % and 42.2 %, respectively, after 120 days. For the Omicron variant, aVE within 12-120 days post-second dose was 61.1 % (BNT162b2) and 85.1 % (mRNA-1273), decreasing to 36.7 % and 24.9 %, respectively, after 120 days. After a booster dose of mRNA-1273, aVE was 64.0 % (BNT162b2 recipients) and 65.9 % (initial mRNA-1273 recipients). Regardless of variant, aVE for hospitalization prevention after 2 doses was 87.0 % (BNT162b2) and 89.0 % (mRNA-1273). The administration of two doses of Moderna-mRNA-1273 against SARS-CoV-2 in HCWs proved to be highly effective in preventing infections and hospitalizations in the first 120 days after the second dose during the predominance of the Omicron variant. The decline in VE after 120 days since the administration of the second dose was significantly restored by the booster dose administration. This increase in VE was greater for the Pfizer vaccine. COVID-19 hospitalization prevention remained stable with both mRNA vaccines throughout the study period.

Jiménez-Sepúlveda N ，Gras-Valentí P ，Chico-Sánchez P ，Castro-García JM ，Ronda-Pérez E ，Vanaclocha H ，Peiró S ，Burgos JS ，Ana Berenguer ，Navarro D ，Sánchez-Payá J ，Valencian vaccine research program ProVaVac study group ... -  《-》

Association Between 3 Doses of mRNA COVID-19 Vaccine and Symptomatic Infection Caused by the SARS-CoV-2 Omicron and Delta Variants.

Accorsi EK ，Britton A ，Fleming-Dutra KE ，Smith ZR ，Shang N ，Derado G ，Miller J ，Schrag SJ ，Verani JR ... -  《-》

Estimated BNT162b2 Vaccine Effectiveness Against Infection With Delta and Omicron Variants Among US Children 5 to 11 Years of Age.

Khan FL ，Nguyen JL ，Singh TG ，Puzniak LA ，Wiemken TL ，Schrecker JP ，Taitel MS ，Zamparo JM ，Jodar L ，McLaughlin JM ... -  《JAMA Network Open》