A study conducted on healthcare workers who had received at least one dose of a Covid-19 vaccine at a hospital in India’s capital, Delhi, found that “breakthrough” infections happened in about one in seven individuals.
However only one person required hospitalisation and experts have stressed that jabs still offer good protection against the Indian variant.
Breakthrough cases are those in which people get infected with Covid-19 even after getting a vaccine shot.
The study was conducted on 113 employees of Fortis Centre of Excellence for Diabetes, Metabolic Diseases and Endocrinology, according to The Indian Express.
Breakthrough symptomatic Covid-19 infections, after 14 days of the second dose, occurred in 15 individuals, or 13.3 per cent of the 113 participants. “Except one who required hospitalisation, all 14 persons with breakthrough infections had mild Covid-19 disease,” Dr Anoop Misra, chairman of the Fortis centre, told the paper.
Out of the 113 participants, 28 had received Covaxin – a homegrown vaccine developed by Bharat Biotech – and 85 were vaccinated with Covishield – the Oxford-AstraZeneca vaccine produced by Serum Institute of India. A total of 107 people in the study had received the second dose of the vaccine.
India’s health ministry has said that adequate immune response is only formed two-to-three weeks after the second dose of the vaccine is administered.
The Indian government said last month that the breakthrough infection rate after taking the first and the second dose of the Covid-19 vaccines approved in the country remained low. Data from Indian Council of Medical Research showed that only about two to four vaccinated people per 10,000 had been infected.
The authors of the study on Fortis employees said that breakthrough infections after adequate vaccinations are a matter of concern, but adequate data is not yet available, according to news agency Press Trust of India (PTI).
They also acknowledged that the study had a small sample size and no data on obesity and co-morbid diseases of the participants. The study did not include asymptomatic infections.
Experts and medical professionals have repeatedly said that while there may be cases of Covid-19 infections post inoculation, this does not mean that the vaccines are not working. They have said that vaccines help reduce the risk of severe illness and death.
“None of the vaccines currently available provide protection against transmission of the virus. Statistically speaking, infection post-vaccination is likely to be milder than one without," Vineeta Bal, an immunologist from Pune's Indian Institute of Science, Education and Research, told PTI.
The World Health Organisation classified a coronavirus variant first spotted in India as a “variant of concern” on Monday. The organisation’s technical lead said there may be some evidence of “reduced neutralisation” in terms of vaccine effectiveness against the variant, according to BBC.
But Rakesh Mishra, director of the Centre for Cellular and Molecular Biology in Hyderabad, has said that both Covaxin and Covishield are effective against the Indian variant in preventing serious illness.