Some countries may have started offering booster doses as an option to counter virulent Delta variant of Covid-19, but an international group of scientists has rejected the idea of giving booster dose to combat Delta variant, asserting that vaccine efficacy against the severe virus is so high that booster doses for the general population are “not appropriate” at this stage in the pandemic.
The World Health Organization (WHO) also has disfavored the idea of giving third doses to all stating that it may be necessary for the most at-risk populations. “But for now, we do not want to see widespread use of boosters for healthy people who are fully vaccinated,” the WHO has said.
Published in the Lancet journal, the review by the scientists, including from the WHO and two from the US Food and Drug Administration (FDA), 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.
The observation comes even as the US 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.
India too has been contemplating giving booster dose to the vaccinated people having low antibody levels.
“The move is being contemplated as over 20 per cent of the inoculated population has failed to develop antibodies against SARS-CoV2,” Director of Bhubaneswar-based Institute of Life Sciences (ILS) Dr Ajay Parida had recently indicated.
However, lead author Ana-Maria Henao-Restrepo from the WHO in the review in the Lancet noted that 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 the lead author.
Last week, Pascal Soriot, CEO of AstraZeneca, also said a third dose of vaccines against Covid-19 may not be needed for everyone.
The WHO has, meanwhile, called for an extension of a global moratorium on Covid-19 booster doses, with an aim to enable every country to vaccinate at least 40 per cent of its population.
According to the WHO, globally 5.5 billion vaccine doses have been administered, but 80 per cent have been administered in high-and upper-middle income countries.
“The vaccines that are currently available are safe, effective, and save lives. Although the idea of further reducing the number of Covid-19 cases by enhancing immunity in vaccinated people is appealing, any decision to do so should be evidence-based and consider the benefits and risks for individuals and society.
“These high-stakes decisions should be based on robust evidence and international scientific discussion,” added co-author Soumya Swaminathan, WHO chief scientist.