3 doses of same or mixed jabs work equally well against Covid: Study

A medic inoculates a girl with a dose of Covaxin, in New Delhi. File pic/AFP

Three doses of the same COVID-19 vaccine or a combination of different jabs work well in preventing infections, even against different variants, according to the largest study of its kind. However, the effectiveness of three dose vaccine regimens against COVID-related death remains uncertain, the findings show.

The findings, published in The BMJ, suggest that the number of vaccine doses seems to be the key to improving immunity rather than the combinations of vaccine types.

The researchers from the Chinese University of Hong Kong analysed 38 World Health Organization COVID databases for published studies and preprints on a weekly basis from March 8, 2022. They identified 53 studies involving over 100 million participants with 24 combinations of approved vaccine courses and seven different vaccine types for analysis.

"While a three dose mRNA regimen seems to be the most effective in preventing COVID-19 infections, any heterolo-gous [same vaccine] and homo-logous [mixed vaccine] three dose regimens work comparably well in preventing COVID infections, even against different variants," the authors said.

The researchers found that three doses of any mRNA vaccine appear to be most effective (96 per cent) against non-severe COVID-19 infections and most effective (95 per cent) in reducing hospital admission.

The results also show that any three dose regimen - heterologous or homologous - nduces higher immunity in all age groups, even in the over 65s, than a two dose homologous regimen, according to the researchers. A third booster dose is needed to prevent infection caused by the Omicron variant, they said.

4,31,60,832 Total no. of Coronavirus cases in india so far
5,24,636 Total no. of deaths due to the virus in India so far
18,386 Total no. of active cases in India

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