30 pc of vaccinated people lose antibodies in 6 months: AIG study

About 70 per cent of the population, particularly youngsters, are able to retain Covid antibodies till nine months after getting the second dose of vaccine. The bad news is that the remaining 30 per cent of the vaccinated population, particularly those 40 years and above with co-morbidities, do not retain enough antibodies to tackle the infection.

Lending credence to the argument that the gap between the second dose and booster dose should be reduced to six months, a study conducted by AIG Hospitals has found that about 30 per cent of the people lost vaccine-induced immunity six months after taking the second dose. AIG coducted the study in association with Asian Healthcare Foundation.

“The study aimed to understand the effectiveness of current vaccines over the long-term and see if there are specific population demography who need a booster at the earliest,” said D Nageshwar Reddy, Chairman of AIG Hospitals.

“We are seeing a surge of infection across the country. Fortunately, the severity of the disease is mild because of multiple factors, including the effect of vaccination, the intrinsic character of the variant itself, and natural immunity amongst the population,” he said.

However, the country must devise strategies that could ensure minimal spread and protect as many people as possible, he said.

Antibody levels
“We found that almost 30 per cent individuals had antibody levels below protective immunity level of 100 AU/ml after six months,” said the study.

“These individuals were majorly above 40 years with co-morbidities such as hypertension and diabetes. Of the total sample size, six per cent did not develop any immune protection at all,” he said.

The results clearly indicate that the immunity level wanes with age. Younger people have more sustained antibody levels than the elderly population.

“Individuals above 40 years with diabetes and hypertension of both genders may be at a higher risk of SARS-CoV-2 infection, and these individuals should be prioritised for a booster dose after six months,” said the study.

“At present, the nine-month gap for prevention dose benefits 70 per cent of the population who can retain enough antibody levels beyond six months,” said Reddy.

However, considering the scale of our country, the 30 per cent people, especially those with co-morbid conditions such as hypertension and diabetes, who are more prone to develop an infection after six months of getting fully vaccinated, should also be considered for the prevention dose,” he felt.

Sample size
The study was conducted on a large pool of 1,636 healthcare workers who were fully vaccinated. About 93 per cent of the participants had taken Covishield, 6.2 per cent received Covaxin, and less than 1 per cent received Sputnik vaccine.

Those who had antibodies levels less than 15 AU/ml (arbitrary units per milliliter) were considered antibody-negative. This means that they didn’t develop any protective immunity against the virus. It was estimated that an antibody level of 100 AU/ml is the minimum level for protection against the virus.

Any individual with less than 100 AU/ml antibody level is susceptible to getting infected. The Hindu BusinessLine