Booster dose: Dose gap, natural infection slow offtake among 60-plus

About one-third of the 60-plus population with co-morbidities has so far received their precaution dose of vaccination, since it was launched on January 10. The tepid response, experts say, is due to a variety of reasons, from the long gap of nine months from the second dose, natural infection that occurred in a large number of people during the third wave and in several cases vaccine hesitancy.

As a proportion of the estimated 27 million elderly in the 60-plus with co-morbidity, only 34 per cent have got the third dose since the drive was launched on January 10. Of the total population of over 60 estimated at about 111 million, the coverage falls even shorter.

While intended for the elderly with co-morbidities, the booster dose can effectively be taken by all senior citizens since there is no doctor certification to prove a medical condition is required.

It is, therefore, hard to point out if those who took the third precautionary dose had a co-morbidity, but according to health ministry data, over 9 million such shots have been administered to those aged above 60.

Medical experts said many could have escaped the ordeal after contracting the virus during the third wave had a booster dose been administered in time. Why such low offtake? Doctors said many among the 60-plus got Covid during the third wave, and have to wait for three months to take the next dose.

A senior civic body official in Mumbai said the receding third wave is a reason behind the dip in demand. “Those who are infected during the third wave have to wait for three months before they can take the booster shots,” the official said.
 

A private hospital administrator also said many doctors and nurses had taken the third shot in December itself when cases of Omicron started surfacing. “These were unofficial jabs, and this has resulted in a lower demand in January-February, once the precaution dose was allowed. The Centre was one month too late to announce the policy,” said the administrator of a private hospital in Mumbai.

The other reason is also vaccine hesitancy. V K Paul, member-health Niti Aayog appealed to the elderly population to come forward to take the booster dose.

Sources among vaccine makers say they are awaiting communication from the Centre on booster policy. Serum Institute of India has already approved Covovax as a booster shot for Covishield takers. The Centre is yet to take a call on the same.

Experts are also questioning the nine-month gap between the second and the third doses.

“The gap should be six months. Many lives could be saved if this long gap was not there,” said Jacob John.

Covaxin maker Bharat Biotech has indicated that a booster shot or a third dose of Covaxin given after six months neutralises both the Delta and Omicron variants.

Balram Bhargava, director general, Indian Council of Medical Research (ICMR), justifying the 9-month gap had in December 2021 cited studies from the US that showed that immunological memory post Sars-CoV-2 natural infection lasted for over eight months.

A study from China showed that antibody and cellular responses persist for about nine months after an infection. He said longitudinal studies from the US show most patients had detectable Sars-CoV-2 antibody responses even after 13 months of infection.

“Therefore 8-10 months is the general period of protection. We are taking a more conservative estimate and saying that one is protected for about nine months,” Bhargava said.

A Kolkata study found that cell mediated immunity after Covishield and Covaxin lasted 10 months while another study in Kerala showed that hybrid immunity with Covishield is stronger than only infection-induced immunity.