Post by Pakachoag Phreek on Aug 12, 2022 17:24:39 GMT -5
The rapid emergence of the B.1.1.529 (Omicron) variant of SARS-CoV-2 led to a global resurgence of coronavirus disease 2019 (COVID-19). Israeli authorities approved a fourth COVID-19 vaccine dose (second booster) for individuals aged 60 years and over who had received a first booster dose 4 or more months earlier. Evidence for the effectiveness of a second booster dose in reducing hospitalizations and mortality due to COVID-19 is warranted. This retrospective cohort study included all members of Clalit Health Services who were aged 60–100 years and who were eligible for the second booster on 3 January 2022. Hospitalizations and mortality due to COVID-19 in participants who received the second booster were compared with those for participants who received one booster dose. Cox proportional hazards regression models with time-dependent covariates were used to estimate the association between the second booster and hospitalization 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. Hospitalization due to COVID-19 occurred in 270 of the second-booster recipients and in 550 participants who received one booster dose (adjusted hazard ratio, 0.36; 95% confidence interval (CI): 0.31–0.43). 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% CI: 0.17–0.28). This study demonstrates a substantial reduction in hospitalizations and deaths due to COVID-19 conferred by a second booster in Israeli adults aged 60 years and over.
[The vaccine is Pfizer only.]
Due to the considerable rise in breakthrough infections by the Omicron variant in individuals who have already received three vaccine doses, the Israeli Ministry of Health initiated a fourth vaccine (second booster) dose campaign to protect those at high risk for severe COVID-19. On 2 January 2022 the second booster dose was approved for individuals 60 years and older, high-risk populations, and healthcare workers who had received a first booster dose at least 4 months earlier
A total of 328,597 participants (58%) from the entire cohort of 563,465 individuals received the second booster dose during the 40 day study period. The association between patient characteristics and the second-booster uptake rate is given in Table 2. Compared with the 60–69 years age group, uptake was 49% higher in the 70–79 years age group and 57% higher in the 80–100 years age group. Higher socioeconomic status was associated with an 18% higher uptake for each additional point in the socioeconomic status. Compared with the general Jewish population, uptake was 19% lower in the Ultra-Orthodox Jewish population and was 41% lower in the minority Arab population.
Primary outcome: death due to COVID-19
During the study period, death due to COVID-19 occurred in 92 of the second-booster recipients and in 232 of the participants in the first-booster group. The adjusted hazard ratio (HR) for death due to COVID-19 in the second-booster group compared with the first-booster group was 0.22 (95% CI: 0.17–0.28)
In participants aged 60–69 years, death from COVID-19 occurred in 5 of 111,776 participants in the second-booster group and in 32 of 123,786 participants in the first-booster group. The adjusted HR for death due to COVID-19 in the second-booster group was 0.16 (95% CI: 0.06–0.41) (Supplementary Table 2).
In participants aged 70–79 years, death from COVID-19 occurred in 22 of 134,656 participants in the second-booster group and in 51 of 74,717 participants in the first-booster group (adjusted HR, 0.28; 95% CI: 0.17–0.46) (Supplementary Table 3).
In participants aged 80–100 years, death from COVID-19 occurred in 65 of 82,165 participants in the second-booster group and in 149 of 36,365 participants in the first-booster group (adjusted HR, 0.20; 95% CI: 0.15–0.27) (Supplementary Table 4).
Secondary outcome: hospitalization due to COVID-19
During the study, hospitalization due to COVID-19 occurred in 270 of the second-booster recipients and in 550 participants in the first-booster group. The adjusted HR for hospitalization due to COVID-19 in the second-booster group compared with the first-booster group was 0.36 (95% CI: 0.31–0.43)
In the Cox regression model, compared with the 60–69 years age group, the 70–79 years and 80–100 years age groups were associated with significantly higher hospitalization rates due to COVID-19 (HR 1.82, 95% CI: 1.48–2.25 and HR 4.04, 95% CI: 3.28–4.97, respectively). The following characteristics also had a significant positive association with death due to COVID-19: male sex (HR 1.53, 95% CI: 1.32–1.78), chronic heart failure (HR 2.17, 95% CI: 1.82–2.60), chronic renal failure (HR 2.27, 95% CI: 1.63–2.67), chronic obstructive pulmonary disease (HR 2.24, 95% CI: 1.84–2.67), diabetes (HR 1.43, 95% CI: 1.24–1.66), hypertension (HR 1.39, 95% CI: 1.15–1.67), ischemic heart disease (HR 1.21, 95% CI: 1.03–1.42) and history of stroke (HR 1.43, 95% CI: 1.20–1.71). The following characteristics were associated with lower hospitalization rates: Arab population sector (HR 0.60, 95% CI: 0.44–0.82) and lower socioeconomic status (HR 0.92, 95% CI: 0.88–0.95).
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In this study we did not analyze the impact of the second booster on breakthrough infections because it is prone to introduce various methodological caveats. In Israel, during the Omicron surge (Extended Data Fig. 5) the vast majority of COVID-19 tests were done by the patients themselves at home by rapid antigen testing. Not everyone who received a positive result went on to confirm the result at an official state-regulated rapid antigen test center. Therefore, we could not rely only on confirmed infection rates for vaccine effectiveness analysis. Moreover, we assumed that because the Omicron variant caused only mild symptoms in many cases, many infected people preferred not to get tested.
This study did not evaluate mortality risk reduction in the second-booster group compared with totally unvaccinated individuals. Unvaccinated individuals comprise a very small proportion of the population
[The vaccine is Pfizer only.]
Due to the considerable rise in breakthrough infections by the Omicron variant in individuals who have already received three vaccine doses, the Israeli Ministry of Health initiated a fourth vaccine (second booster) dose campaign to protect those at high risk for severe COVID-19. On 2 January 2022 the second booster dose was approved for individuals 60 years and older, high-risk populations, and healthcare workers who had received a first booster dose at least 4 months earlier
A total of 328,597 participants (58%) from the entire cohort of 563,465 individuals received the second booster dose during the 40 day study period. The association between patient characteristics and the second-booster uptake rate is given in Table 2. Compared with the 60–69 years age group, uptake was 49% higher in the 70–79 years age group and 57% higher in the 80–100 years age group. Higher socioeconomic status was associated with an 18% higher uptake for each additional point in the socioeconomic status. Compared with the general Jewish population, uptake was 19% lower in the Ultra-Orthodox Jewish population and was 41% lower in the minority Arab population.
Primary outcome: death due to COVID-19
During the study period, death due to COVID-19 occurred in 92 of the second-booster recipients and in 232 of the participants in the first-booster group. The adjusted hazard ratio (HR) for death due to COVID-19 in the second-booster group compared with the first-booster group was 0.22 (95% CI: 0.17–0.28)
In participants aged 60–69 years, death from COVID-19 occurred in 5 of 111,776 participants in the second-booster group and in 32 of 123,786 participants in the first-booster group. The adjusted HR for death due to COVID-19 in the second-booster group was 0.16 (95% CI: 0.06–0.41) (Supplementary Table 2).
In participants aged 70–79 years, death from COVID-19 occurred in 22 of 134,656 participants in the second-booster group and in 51 of 74,717 participants in the first-booster group (adjusted HR, 0.28; 95% CI: 0.17–0.46) (Supplementary Table 3).
In participants aged 80–100 years, death from COVID-19 occurred in 65 of 82,165 participants in the second-booster group and in 149 of 36,365 participants in the first-booster group (adjusted HR, 0.20; 95% CI: 0.15–0.27) (Supplementary Table 4).
Secondary outcome: hospitalization due to COVID-19
During the study, hospitalization due to COVID-19 occurred in 270 of the second-booster recipients and in 550 participants in the first-booster group. The adjusted HR for hospitalization due to COVID-19 in the second-booster group compared with the first-booster group was 0.36 (95% CI: 0.31–0.43)
In the Cox regression model, compared with the 60–69 years age group, the 70–79 years and 80–100 years age groups were associated with significantly higher hospitalization rates due to COVID-19 (HR 1.82, 95% CI: 1.48–2.25 and HR 4.04, 95% CI: 3.28–4.97, respectively). The following characteristics also had a significant positive association with death due to COVID-19: male sex (HR 1.53, 95% CI: 1.32–1.78), chronic heart failure (HR 2.17, 95% CI: 1.82–2.60), chronic renal failure (HR 2.27, 95% CI: 1.63–2.67), chronic obstructive pulmonary disease (HR 2.24, 95% CI: 1.84–2.67), diabetes (HR 1.43, 95% CI: 1.24–1.66), hypertension (HR 1.39, 95% CI: 1.15–1.67), ischemic heart disease (HR 1.21, 95% CI: 1.03–1.42) and history of stroke (HR 1.43, 95% CI: 1.20–1.71). The following characteristics were associated with lower hospitalization rates: Arab population sector (HR 0.60, 95% CI: 0.44–0.82) and lower socioeconomic status (HR 0.92, 95% CI: 0.88–0.95).
.....
In this study we did not analyze the impact of the second booster on breakthrough infections because it is prone to introduce various methodological caveats. In Israel, during the Omicron surge (Extended Data Fig. 5) the vast majority of COVID-19 tests were done by the patients themselves at home by rapid antigen testing. Not everyone who received a positive result went on to confirm the result at an official state-regulated rapid antigen test center. Therefore, we could not rely only on confirmed infection rates for vaccine effectiveness analysis. Moreover, we assumed that because the Omicron variant caused only mild symptoms in many cases, many infected people preferred not to get tested.
This study did not evaluate mortality risk reduction in the second-booster group compared with totally unvaccinated individuals. Unvaccinated individuals comprise a very small proportion of the population