Single Covishield vaccine shot sufficient for recovered persons: Study

RNS: A single dose of Covishield Vaccine administered to those recovered from the infection with SARS-CoV-2 indicated these people were more immune against Covid-19 than those who were not previously exposed, reveals a study published in a peer-reviewed journal, International Journal of Infectious Diseases.

The research was conducted by the Asian Institute of Gastroenterology (AIG) Hospitals on 260 healthcare workers who got vaccinated between 16 January and 5 February. They were divided into two groups – the first comprised those who were RT-PCR positive for SARS-CoV-2 (seropositive) and had recovered while the second group comprised of those who were found RT-PCR negative (seronegative) and were categorised as no prior exposure.

All participants were given the Covishield the Oxford-AstraZeneca vaccine manufactured by Serum Institute of India, Pune.

“All the seropositive or seronegative participants developed neutralizing antibodies by day 28 after the first dose of Covishield. The previously infected group mounted greater antibody response to a single dose of Covishield vaccine compared with the no prior exposure group,” the study reveals.

The previously infected group of healthcare workers also demonstrated larger T- and B-cell responses in addition to the better immune response, it said. “These results show that pre-exposed individuals should have protective immunological memory following a single dose of vaccination. Such people could mount a memory recall response after an antigen, as adaptive immunological memory has established,” the research revealed.

The researchers cited their findings and focused on a “single-dose vaccination strategy” to boost the coverage of immunisations. “Persons with and recovering from COVID-19 would be protected with just one single vaccine dosage. Our results show that a single-dose method to enhanced coverage and protect a wide number of populations is supported by previously infected persons,” the study added.

Meanwhile, the researchers, note that all individuals with no prior exposure to COVID-19 “would be required to take the second vaccination dose.”

However, the Union Health Ministry clarified on 1 June that is not considering immunising the beneficiaries with only a single dose of the vaccine.

“There is absolutely no change in the schedule of Covishield doses; it will be two doses only. After the first Covishield dose is administered, the second dose will be given after 12 weeks. The same schedule applies to Covaxin,” told Dr VK Paul Niti Aayog member.

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