New York: Vaccine efficacy against severe Covid-19 is so high, even for the Delta variant, that booster doses for the general population are "not appropriate" at this stage in the pandemic, an international group of scientists argued in a review published in The Lancet.
The review, which includes scientists from the World Health Organization (WHO) and two from the US Food and Drug Administration (FDA), who will leave the agency, comes even as the latter is currently reviewing evidence for booster doses for Americans; and many other countries including Israel, Italy, France and Russia who have already rolled out the third dose of Covid jabs.
It summarises the currently available evidence from randomised controlled trials and observational studies published in peer-reviewed journals and pre-print servers and asserts that the benefits of the first shots are clear. It added that vaccination had 95 per cent efficacy against severe disease both from the Delta variant and from the Alpha variant, and over 80 per cent efficacy at protecting against any infection from these variants.
Although vaccines are less effective against asymptomatic disease or against transmission than against severe disease, the unvaccinated minority are still the major drivers of transmission, the scientists argued in the review published on Monday.
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"Taken as a whole, the currently available studies do not provide credible evidence of substantially declining protection against severe disease, which is the primary goal of vaccination. Even if some gain can ultimately be obtained from boosting, it will not outweigh the benefits of providing initial protection to the unvaccinated," said lead author Ana-Maria Henao-Restrepo from the WHO.