Single-dose of Covid-19 vaccine shows better immunity in already infected people: Study

Higher memory T and B-cell responses in addition to higher antibody response with a single dose of vaccine given at three to six months after recovery from Covid-19 may be considered at par with two doses of vaccine for individuals already infected with Covid-19.

A single dose of Covishield vaccine given to those who had recovered from the SARS-CoV-2 infection showed these individuals had a stronger immunity to the Covid-19 virus compared to those having no prior exposure, according to a study.

The research conducted by Asian Institute of Gastroenterology (AIG) Hospitals, Hyderabad has been published in the peer-reviewed journal, International Journal of Infectious Diseases.

The research conducted by Asian Institute of Gastroenterology (AIG) Hospitals, Hyderabad has been published in the peer-reviewed journal, International Journal of Infectious Diseases.

The study was conducted on 260 healthcare workers who got vaccinated between January 16 and February 5. They were divided into two groups - the first comprised those who were RT-PCR positive for SARS-CoV-2 and had recovered while the second group comprised of those who were found RT-PCR negative and were categorised as no prior exposure.

All participants were given the Covishield vaccine, manufactured by Pune's Serum Institute of India.

The two significant observations that came out of the study.

Firstly, the previously infected group (people who got infected with Covid-19) showed a greater antibody response to a single dose of vaccine compared with those who had no prior infection.

Secondly, Memory T-cell responses elicited by a single dose of vaccine were significantly higher in the previously infected group compared with those who had no prior infection.

It was concluded that higher memory T and B-cell responses in addition to higher antibody response with a single dose of vaccine given at three to six months after recovery from Covid-19 may be considered at par with two doses of vaccine for individuals already infected with Covid-19.

Commenting on the impact that this study can have on the overall vaccine administration strategy, Dr D Nageshwar Reddy, Chairman, AIG Hospitals, and one of the co-authors of the study said, "The results show that people who got infected with Covid-19 need not take two doses of vaccine yet with a single dose can develop robust antibody and memory cell response at par with two-doses for those who didn't get the infection. This will significantly help at a time when there's a shortage of vaccines in the country and more people can be covered using the saved doses."

Dr Reddy further added, "Once we attain the requisite number of people vaccinated for achieving herd immunity, these patients who got infected and received only one dose can take the second dose of the vaccine. At this point, all our strategies should be directed at the widespread distribution of available vaccines and to include the maximum number of people at least with a single dose."

"During the second Covid-19 wave, when cases were growing exponentially, the Covid-19 vaccination rate took a downturn. As of April 27, when the growth rate of active infection was near 5 per cent and the growth of vaccinated people was just 1.4 per cent. We need to modify vaccination strategy based on scientific evidence and with the objective that a larger set of the population can be covered in the shortest duration", the study by AIG hospitals said.