Covid-19 antibodies in 40+ age group with comorbidities lower after six months of second dose: Study

A study by the Hyderabad based AIG hospitals showed that people above 40 years and with comorbidities like hypertension and diabetes have significantly lesser antibody responses to Covid-19 after six months of full vaccination.

The results pointed out that immunity waning is directly proportional to age, meaning younger people have more sustained antibody levels than the elderly population.

The study was conducted on a pool of 1,636 healthcare workers and indicated that about 30 % of individuals have lost their vaccine-acquired immunity after six months.

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AIG researchers said that their study was aimed to understand the effectiveness of current vaccines over the long-term and examine if any specific population demography needs a booster shot at the earliest.

“As individuals above 40 years of both genders with diabetes and hypertension may be at a higher risk of SARS-CoV-2 infection, this group should also be prioritized for a booster dose after six months (of first two doses),” said Dr D Nageshwar Reddy, Chairman, AIG Hospitals.

A 9-month gap rule is being applied now by the government for availing the prevention booster dose.

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Researchers measured the IgG anti-S1 and IgG anti-S2 antibodies to SARS-CoV-2 in the 1,636 individuals. Those who had antibody levels less than 15 AU/ml were considered antibody negative, which means they did not develop any protective immunity against the virus.

Further, antibody levels of 100 AU/ml are considered as the minimum level of protection against the virus, meaning any individual with lesser antibodies is reasoned as susceptible to getting infected.

Of the 1,636 participants, 93% had received Covishield, 6.2% took Covaxin and less than one % received Sputnik. Out of the total, six per cent did not develop any immune protection at all.

“We are (again) seeing a surge of Covid-19 infection across the country. Fortunately, the severity of the disease is mild now because of multiple factors like vaccination, the intrinsic character of the variant itself, and natural immunity amongst the population. However, we need to devise strategies that can ensure minimal spread and protect as many people as possible,” Dr Reddy opined.

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