Explore the vast range of titles available.

Israel began administering a BNT162b2 booster dose to restore protection following the waning of the 2-dose vaccine. Biological studies have shown that a “fresh” booster dose leads to increased antibody levels compared to a fresh 2-dose vaccine, which may suggest increased effectiveness. To compare the real-world effectiveness of a fresh (up to 60 days) booster dose with that of a fresh 2-dose vaccine, we took advantage of a quasi-experimental study that compares populations that were eligible to receive the vaccine at different times due to age-dependent policies. Specifically, we compared the confirmed infection rates in adolescents aged 12–14 (215,653 individuals) who received the 2-dose vaccine and in adolescents aged 16–18 (103,454 individuals) who received the booster dose. Our analysis shows that the confirmed infection rate was lower by a factor of 3.7 (95% CI: 2.7 to 5.2) in the booster group. This study compares SARS-CoV-2 infection rates following a recent second or third dose of the BNT162b2 (Pfizer/BioNTech) vaccine. They use data from Israel for 12–14 year olds (second dose) and 16–18 year olds (third dose), and find a 3.7-fold higher risk in the second-dose group.

Since July 30, 2021, more than a million fully vaccinated Israeli residents who were 60 years of age or older have received a third dose of the BNT162b2 mRNA vaccine. As of August 31, the rate of confirmed Covid-19 infection was lower in the booster group than in the nonbooster group by a factor of 11.3, and the rate of severe illness was lower by a factor of 19.5.

Investigators from Israel explored the effect of two vaccine doses, three vaccine doses, and previous SARS-CoV-2 infection (without vaccination and before or after vaccination) on subsequent SARS-CoV-2 infection and progression to severe illness. Previous immunity-conferring events (vaccination or infection) were identified as being protective, but all protection waned with time.

The spread of the omicron variant produced an increase in Covid-19 in Israel in late 2021, and a second boost of BNT162b2 vaccine was authorized in early January 2022. This article reports the efficacy of the fourth dose among Israeli citizens 60 years of age or older. Rates of severe illness were reduced by a factor of 3.5 in the fourth week after the second boost.

In a study involving 4.7 million fully vaccinated persons in Israel, the rate of confirmed Covid-19 was lower among those who received a booster than among those who did not by a factor of approximately 10. Among participants 60 years of age or older, the rate of severe illness was lower by a factor of 17.9 and the rate of death by a factor of 14.7.

This study aims to address limitations in assessing vaccine protection using the classical vaccine effectiveness (VE) measure, especially in contexts where a significant portion of the population is already vaccinated or infected. We propose using the adjusted number of cases (ANC) as a building block for deriving vaccine effectiveness measures. This approach accounts for biases arising from small and unrepresentative unvaccinated reference groups with incomplete data. We demonstrate the use of these measures for assessing the protection conferred by a booster dose against severe COVID-19 using data from Israel. The use of ANC and the derived measures reveals a more comprehensive understanding of the complex immunity landscape compared to traditional VE measures. This approach enables meaningful comparisons between different vaccination categories and provides insights to inform policy decisions. In situations with widespread vaccination and prior infections, traditional VE measures can be limited in their informative value. Using the ANC offers a more robust and insightful assessment of vaccine effectiveness. A demonstration of the evaluation of booster dose protection against severe COVID-19 in Israel underscores the importance of adopting complementary measures to guide public health strategies.

Following evidence of waning immunity against both infection and severe disease after 2 doses of the BNT162b2 vaccine, Israel began administering a 3rd BNT162b2 dose (booster) in July 2021. Recent studies showed that the 3rd dose provides a much lower protection against infection with the Omicron variant compared to the Delta variant and that this protection wanes quickly. However, there is little evidence regarding the protection of the 3rd dose against Omicron (BA.1/BA.2) severe disease. In this study, we estimate the preservation of immunity from severe disease up to 7 months after receiving the booster dose. We calculate rates of severe SARS-CoV-2 disease between groups of individuals aged 60 and above, comparing those who received two doses at least 4 months previously to those who received the 3rd dose (stratified by the time from vaccination), and to those who received a 4th dose. The analysis shows that protection conferred by the 3rd dose against Omicron severe disease did not wane over a 7-month period. Moreover, a 4th dose further improved protection, with a severe disease rate approximately 3-fold lower than in the 3-dose cohorts. Patient data from the Israeli Ministry of Health demonstrates that a 3rd dose of BNT162b2 is effective in reducing Omicron BA.1/BA.2 severe disease and does not wane over the seven month study period as well as that a fourth dose further improves the protective features of vaccination.

A resurgence of Covid-19 in mid-June prompted an examination of Covid-19 immunity as a function of month of vaccination in Israel. Data on confirmed infection and severe disease among fully vaccinated persons were collected from July 11 to 31, 2021. Relative and absolute rates of infection and severe disease increased with time since the second vaccine dose in all age groups.

During a surge in cases of Covid-19 in Israel, a rapid deployment of BNT162b2 booster injections was initiated in long-term care facilities over a 3-week period in July. When infection rates were increasing in the general population, rates in long-term care facilities decreased by 71%, and hospitalization rates fell by 80%.

The BNT162b2 (Pfizer-BioNTech) two-dose vaccine regiment for children and the BNT162b2 third dose for adolescents were approved shortly before the SARS-CoV-2 omicron (B.1.1.529) outbreak in Israel. We aimed to estimate the effects of these vaccines on the rates of confirmed infection against the omicron variant in children and adolescents. In this observational cohort study, we extracted data for the omicron-dominated (sublineage BA.1) period. We compared rates of confirmed SARS-CoV-2 infection between children aged 5–10 years 14–35 days after receiving the second vaccine dose with an internal control group of children 3–7 days after receiving the first dose (when the vaccine is not yet effective). Similarly, we compared confirmed infection rates in adolescents aged 12–15 years 14–60 days after receiving a booster dose with an internal control group of adolescents 3–7 days after receiving the booster dose. We used Poisson regression, adjusting for age, sex, socioeconomic status, calendar week, and exposure. Between Dec 26, 2021, and Jan 8, 2022, we included 1 158 289 participants. In children aged 5–10 years, the adjusted rate of confirmed infection was 2·3 times (95% CI 2·0–2·5) lower in children who received a second dose than in the internal control group. The adjusted infection rate in children who received a second dose was 102 infections per 100 000 risk-days (94–110) compared with 231 infections per 100 000 risk-days (215–248) in the corresponding internal control cohort. In adolescents aged 12–15 years, the booster dose decreased confirmed infection rates by 3·3 times (2·8–4·0) compared with in the internal control group. The adjusted infection rate of the booster cohort was 70 per 100 000 risk-days (60–81) compared with 232 per 100 000 risk-days (212–254) in the internal control cohort. A recent two-dose vaccination regimen with BNT162b2 and a recent booster dose in adolescents substantially reduced the rate of confirmed infection compared with the internal control groups. Future studies are needed to assess the duration of this protection and protection against other outcomes such as paediatric inflammatory multisystem syndrome temporally associated with SARS-CoV-2 and long-COVID. None.