The question remains if we have developed infection-led herd immunity after two major waves
A Lancet study published on January 1 says: “Randomised controlled trials and real-world effectiveness studies (in Scotland, Brazil) have shown the considerable short-term protection offered by COVID-19 vaccines”. It says the protection against symptomatic infection began decreasing within three months of the second dose. In Scotland, the effectiveness initially remained relatively stable between 2-3 weeks and 6-7 weeks after the second dose, then decreased up to 18-19 weeks after the second dose. Other studies reveal that fully vaccinated people lose half their antibodies every 108 days. Does it mean the efficacy is strikingly less a year later? Such studies are the basis for recommending a third, booster dose because people receiving boosters have lesser chances of getting a severe infection. This raises certain questions about the vaccination cycles and current and future directions of vaccine research thatthe Indian Council of Medicine Research and National Technical Advisory on Immunization need to address. The first question relates to a vaccine paradox: You notice that every 7-9 months,a section of the population that is fully vaccinated ends up with reduced vaccine efficacy. It is only a notch better than the unvaccinated population when it comes to facing a highly transmissible variant. There comes a time in the vaccination process when both the unvaccinated and a section of the vaccinated await a dose, first dose for the former, third or booster dose for the latter. Thus, these two segments together face a threat from the prevalent coronavirus variant. Our scientists need to tell us how to come out of this disturbing cycle. Current government guidelines indicate there are two solutions in play for the time being: Reduce the rate of infection through vaccination, irrespective of the levels of efficacy dictated by the passage of time. Reduce transmission through social distancing measures like work from home and weekend curfews. Our virologists must tell us if it is possible for neutralising antibodies that can attack viruses before they infiltrate cellsto have a constant staying power over time. For, if not, the third, booster dose is the real option for the fully vaccinated population; not just for those above 60 but for all age groups. The other alternative is to hope for a scientific breakthrough to improve the cellular immunity that can fully protect from disease.
The second question relates to herd immunity. The COWIN website says 88 crore people have received the first dose so far and 63 crore, both doses. There is still time for us to reach vaccination-led herd immunity. Do we at least have infection-led herd immunity, considering we have already faced two major waves? A related question is, with the original virus regularly mutating, do we need to achieve herd immunity for each variant? Or achieving it once is enough? If antibodies made when infected with one virus variant can protect against other variants, we can have broad protection at the national level. Is that the best to hope for?