COVID-19 vaccination works equally well if an individual receives the same type of injection or a mixture of different brands, according to a wide-ranging analysis published today.
The number of doses is the key to protection, found Dr Peter Pak-Hang Cheung at the Chinese University of Hong Kong, and colleagues.
They investigated the effectiveness of vaccine combinations, with a special focus on particular populations such as older or immunocompromised people.
The team searched 38 World Health Organization COVID-19 databases for studies on various vaccine regimens and found 53 reliable studies.
In BMJ today they write: "Three dose mRNA is the most effective in reducing COVID-19 related hospital admission."
They add that, in the subgroup analyses, "a three dose regimen is similarly effective in all age groups, even in the older population (65 years or above). It also works comparably well in patients who are immunocompromised."
The authors explain that adding an mRNA booster to any primary vaccination "confers a high level of protection similar to a homologous three dose mRNA regimen", and that the third dose is needed to prevent infection caused by the omicron variant.
However, they also point out that: "The effectiveness of three dose vaccine regimens against COVID-19 mortality remains uncertain.
"Our findings will serve as a reference for clinicians, public health policy makers, and researchers for vaccine related purposes, such as making recommendations to patients and public health decision making," they conclude.
Au, W. Y. et al. Effectiveness of heterologous and homologous COVID-19 vaccine regimens: living systematic review with network meta-analysis. BMJ 1 June 2022; doi: 10.1136/bmj-2022-069989
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