Protection by 4th dose of BNT162b2 against Omicron in Israel

Abstract

BACKGROUND On January 2, 2022, Israel began administering a fourth dose of BNT162b2 vaccine (Pfizer-BioNTech) to people aged over 60 years and at-risk populations, who had received a third dose of vaccine at least 4 months earlier. The effect of the fourth dose on confirmed coronavirus 2019 disease (Covid-19) and severe illness are still unclear. METHODS We extracted data for the Omicron-dominated period January 15 through January 27, 2022, from the Israeli Ministry of Health database regarding 1,138,681 persons aged over 60 years and eligible for the fourth dose. We compared the rate of confirmed Covid-19 and severe illness between those who had received a fourth dose at least 12 days earlier, those who had received only three doses, and those 3 to 7 days after receiving the fourth dose. We used Poisson regression after adjusting for possible confounding factors. RESULTS The rate of confirmed infection was lower in people 12 or more days after their fourth dose than among those who received only three doses and those 3 to 7 days after vaccination by factors of 2.0 (95% confidence interval [CI], 2.0 to 2.1) and 1.9 (95% CI, 1.8 to 2.0), respectively. The rate of severe illness was lower by factors of 4.3 (95% CI, 2.4 to 7.6) and 4.0 (95% CI, 2.2 to 7.5). CONCLUSIONS Rates of confirmed Covid-19 and severe illness were lower following a fourth dose compared to only three doses.

4th Dose COVID mRNA Vaccines’ Immunogenicity & Efficacy Against Omicron VOC

“…Thus, the major objective for vaccinating HCW was not achieved. The increased efficacy against symptomatic compared to asymptomatic infections found in this study suggest that the fourth dose may be more efficacious against severe disease and death, as was recently observed 22 . Therefore, older and vulnerable populations who are at higher risk for severe disease may benefit most from a fourth vaccine dose.…”

Questioning the justification for a fourth SARS-CoV-2 vaccine

“…In fact, in all scenarios tested, rates of expected adverse events associated with averting a single severe case in the unvaccinated are a fraction of those foreseen in 3 rd dose recipients. It should be noted, that our last assumption of a change in vaccine effectiveness from 80% for third dose recipients to 94.5% among 4 th dose recipients is in accordance with the findings of a very recent analysis from Israeli showing a relative risk of 0.25 for a fourth vs. third dose in preventing severe disease( 6 ). Notably, since the option of receiving the fourth dose became available, over 700000 Israelis have received this dose, however only 132,000 new individuals have received a first and second dose, most of them children.…”

Second Booster Vaccine and Covid-19 Mortality in Adults 60 to 100 Years Old

“…Due to the signi cant rise in breakthrough infections by the omicron variant in individuals who already received three vaccine doses, the Israeli Ministry of Health initiated a fourth vaccine (second-booster) dose campaign to protect the population at high risk for severe disease. On January 2nd, 2022, the second-booster dose was approved to subjects 60 years and older, high-risk populations, and healthcare workers who received a rst booster dose at least four months earlier (1,2).…”

“…Due to the lack of epidemiological and large-scale clinical evidence, the decision on an additional booster dose was made highly controversial (3)(4)(5)(6). Initial short-term results of the effectiveness of providing a second-booster dose of the BNT162b2 messenger RNA vaccine (P zer-BioNTech) for the aging population in lowering rates of con rmed Covid-19 and severe illness have been published recently (2). However, evidence regarding the effectiveness of the additional booster dose in avoiding death due to Covid-19 is warranted.…”