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

Abstract

The rapid emergence of the B.1.1.529 (omicron) variant of severe acute respiratory syndrome coronavirus-2 led to a global resurgence of coronavirus disease 2019 (Covid-19). Israeli authorities approved a 4th Covid-19 vaccine dose (second-booster) for individuals aged 60 and above who received a first booster dose four or more months earlier. Evidence regarding the effectiveness of a second-booster dose in reducing mortality due to Covid-19 is warranted. This retrospective cohort study included all members of Clalit Health Services, aged 60 to 100, eligible for the second-booster. Mortality due to Covid-19 among participants who received the second-booster was compared with participants who received one booster dose. A Cox proportional-hazards regression model with time-dependent covariates was used to estimate the association between the second-booster and death due to Covid-19 while adjusting for demographic factors and coexisting illnesses. A total of 563,465 participants met the eligibility criteria. Of those, 328,597 (58%) received a second-booster dose during the 40-day study period. Death due to Covid-19 occurred in 92 second-booster recipients and in 232 participants who received one booster dose (adjusted hazard ratio 0.22; 95% confidence interval 0.17 to 0.28). This study demonstrates a substantial reduction in Covid-19 mortality by the second-booster in eligible subjects.

Hospitalized patients with severe COVID-19 during the Omicron wave in Israel - benefits of a fourth vaccine dose

“…VE against infection was modest and declined rapidly. Two other studies comparing four- to three-dose recipients, reported VE of 64-73% against severe disease at a 4-9 week follow-up [10,11], and 88% against mortality during a 10-week follow-up [14]. Our findings show another added benefit from the fourth dose.…”

“…Vaccination against SARS-CoV-2 has resulted in a significant change in the response to COVID-19 since the end of 2021. Nevertheless, due to waning immunity [1][2][3], a third dose given as a booster became an essential countermeasure during the Delta variant wave a few months later [4,5]. The spread of the Omicron variant has challenged even the most vaccinated populations, with lower vaccine effectiveness (VE) and high rate of breakthrough infections [6][7][8].…”

Covid-19: Americans who are over 50 or immunocompromised are advised to have second booster

“…A preprint of another Israeli study showed that mortality from covid-19 was 78% lower after a second booster in a group of people over 60 6…”

UpToDate®

“…1,2 Vaccine effectiveness following a primary series and single booster dose appears to wane, and observational studies suggest that a second booster dose is associated with increased protection against severe COVID-19 and death. 3,4 However, the absolute benefi t may be very small and the duration of effect is uncertain. Among those eligible for a second booster dose, we individualize the decision based on patient preference, risk for severe disease, and risk of exposure; those at the highest risk are most likely to benefi t.…”