According to Lancet review, even for the delta variant, the vaccination effectiveness against severe COVID-19 is so high that third doses for the general population are not acceptable at this stage in the pandemic.
A Lancet Viewpoint article on the argument for and against COVID-19 vaccine boosters, co-authored by a global team of leading COVID-19 scientists, was issued on Monday.
While the idea of enhancing immunity in vaccinated people to reduce the number of COVID-19 cases caused by the highly transmissible delta variant is appealing, the authors of the opinion piece emphasise that any decision should be evidence-based and weigh the benefits and risks for individuals and society.
Experts from the World Health Organization (WHO) and the US Food and Drug Administration (FDA) compiled data from randomised controlled trials and observational studies issued in peer-reviewed journals and pre-print servers.
Focus Vaccine Disparity
Even though vaccinations are less effective against asymptomatic, in societies with high vaccination coverage, the non-vaccinated remains the primary cause of spreading and is at risk of severe disease.
The Lancet authors noted that even if boosting can derive some advantage in the long run, it will not surpass the benefits of giving initial protection to the unvaccinated.
Thus they stated that deploying vaccines where they will be most effective will be more helpful, that they could speed the end of the pandemic by preventing variant evolution.
The review’s co-author Soumya Swaminathan, WHO Chief scientist, stated, “The vaccines that are currently available are safe, effective, and save lives,”
Booster Strategies
The Lancet report comes as the United States moves closer to delivering booster injections to significant portions of the population, despite its ongoing difficulty to persuade Americans to get vaccinated in the first place.
Tedros Adhanom Ghebreyesus, the chief of the World Health Organization, has requested that wealthier countries with extensive stocks of COVID-19 vaccines hold off on administering booster shots until the end of the year and make the doses available to poorer countries.
The Africa Centers for Disease Control and Prevention‘s director, John Nkengasong, stated that “we have not seen enough science” to guide judgments on whether to offer booster doses.
Health officials in the United States have defended the administration’s plan to provide additional protection against the virus with a booster vaccine dose, even as others wait for their first shots.
Countries like France have begun giving third vaccinations to the elderly and those with compromised immune systems.
In contrast, Israel has gone even farther, delivering the third dosage to youngsters aged 12 and above five months after their first immunisation.
According to a Bloomberg report, Israel is preparing to guarantee enough vaccines if the fourth round of COVID-19 doses is required.
Meanwhile, India has reached a significant milestone by administering 75 crore doses of the COVID-19 vaccination.
The Opinion
On average, the lancet results of observational studies reveal that immunisation is 95 per cent effective against severe disease caused by both the Delta and Alpha variations and over 80 per cent effective against any infection caused by both variants.
Even if antibody levels in vaccinated persons decline with time, the authors point out that this does not always imply that vaccines are less effective against severe disease.
It could be because the protection against severe disease is mediated not only by antibody responses, which can be fleeting with some vaccinations, but also by long-lasting memory responses and cell-mediated immunity.
The ability of vaccines to evoke an antibody response upon current variants shows that they have not yet evolved to the point at which they are likely to skip the memory immune response induced by the vaccines.
Even if new variants that can evade current vaccines do emerge, they are more likely to arise from strains that have already spread widely; thus, it makes sense to employ boosters designed to combat potential new variants.
