How effective is the COVID-19 vaccine?

Since March 2020, South Africa has experienced four different COVID-19 pandemics, each with a different circulating SARS-CoV-2 variant(There are two main types of variants, Beta (B.1.351) or Delta (B.1.617.2)).

South Africa has the eighth-highest number of deaths globally from COVID-19, vaccine supplies have been low, and healthcare workers have been severely affected by their proximity to patients. The Desmond Tu HIV Center assessed the efficacy of a single dose of the Ad26.COV2.S vaccine (Johnson & Johnson) for South African healthcare workers during two waves of COVID-19 transmission in South Africa.

Between February 17 and May 17, 2021, 477102 healthcare workers were enrolled and vaccinated, of whom 357401 (74.9%) were women and 119701 (2.1%) were men, with a median age of 42 years old (33.0-51.0 years). 215813 vaccinated individuals were matched with 215813 unvaccinated individuals. As of July 17, 2021, the specific results are as follows:

1.The single-dose Ad26.COV2.S vaccine showed efficacy against severe COVID-19 disease, post-vaccination COVID-19-related deaths, Beta and Delta variants.

2.Preventing COVID-19-related deaths was 83%, preventing COVID-19-related hospitalizations requiring intensive care or intensive care was 75%, and preventing COVID-19-related hospitalizations was 67%.

3.Vaccine effectiveness was maintained in older adults and those with comorbidities including HIV infection.

4.Vaccine effectiveness consistent across strains of COVID-19 virus.

References

https://doi.org/10.1016/S0140-6736(22)00007-1