Booster dose of Covid-19 vaccines not needed yet, says review in Lancet
There is currently no need for a booster dose against coronavirus disease (Covid-19) in fully inoculated individuals as they continue to be protected even against hospitalisation and death even from the Delta variant, said a review of current evidences. It added that the available vaccine supply will save far more lives if given to those who haven’t been vaccinated at all.
Earlier, the World Health Organisation had called for a moratorium on booster doses till the vaccines reach more people across the globe.
“The limited supply of these vaccines will save the most lives if made available to people who are at appreciable risk of serious disease and have not yet received any vaccine. 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 report, co-authored by WHO chief scientist Soumya Swaminathan, published in Lancet on Monday.
The paper was co-authored by two scientists who recently quit the US Food and Drug Administration, Philip Krause and Marion Gruber.
The report cautions against believing that a dropping titre of neutralising antibodies predicts a decline in efficacy of a vaccine. The ability of vaccines developed using proteins of the original Wuhan variant of the virus to protect against the current variants shows that the virus hasn’t evolved to the point of escaping the memory immune response induced by the vaccines.
In addition, unnecessary boosting that might lead to known adverse events can reduce vaccine acceptance. “There could be risks if boosters are widely introduced too soon, or too frequently, especially with vaccines that can have immune-mediated side-effects (such as myocarditis in mRNA vaccines, or Guillain-Barre syndrome (a condition where the body’s immune system mistakenly attacks its nervous system leading to numbness and paralysis), which has been associated with adenovirus-vectored Covid-19 vaccines). If unnecessary boosting causes severe adverse reactions, there could be implications for vaccine acceptance that go beyond Covid-19 vaccines.”
The researchers conclude that booster doses might eventually be needed because of waning immunity from the current vaccination or the virus evolving to escape the immune response generated by current vaccines and infections. In such a case, vaccines developed based on the newer variants are likely to be more effective.