An Israeli study published in The Lancet examined the effectiveness of a third dose of the Pfizer/BioNTech vaccine against COVID-19. Like other vaccines, the Pfizer/BioNTech is given in two doses. The study was conducted by the Clalit Research Institute along with researchers from Harvard University.

The study examined as many as 728,321 individuals who got jabbed with a third dose. They were compared with 728,321 individuals who had received only two doses at least five months prior.

When those two projects were compared, this is what the study found:

-93% reduction in COVID-19-related hospitalisation

-92% reduction in severe COVID-19 disease

-81% reduction in COVID-19-related death

During the study period, the Delta variant (B.1.617.2) of the coronavirus was present in Israel wreaking havoc. The study that took place between July 30 and September 23, 2021, coincided with Israel’s fourth wave.

The study found out that a third vaccine dose is effective in cutting down the severe corona-related deaths as compared to those who have only gotten two vaccine doses at least 5 months prior, the institute said.

“The study’s large size also allows a more precise assessment of the vaccine’s effectiveness across different time periods, different subpopulations (by sex, age and number of comorbidities), and different severe outcomes (which are rarer and thus require greater sample size). A recent clinical trial conducted by BioNTech included a smaller sample size and did not estimate the third dose’s effects for more severe outcomes,” the Clalit Research Institute said in a statement.

The findings of the two sets of individuals were done after an extensive set of demographic, geographic and health-related attributions that were associated with risk of infection, risk of severe disease, health status and health seeking behaviour.

The COVID study also included an analysis of the population-level effect. It found out that the infection rates began to drop for each age group 7-10 days after that age group became eligible for the third dose.