Delta variant can infect despite Covishield, Covaxin doses: Study

New Delhi: The 'delta' variant of Covid-19 - the version first detected in India in October last year - is capable of infecting people even after they have received both doses of the Covaxin or Covishield vaccines, according to separate studies by AIIMS (Delhi) and the National Centre for Disease Control (NCDC).

It is important to note that the study has NOT been peer-reviewed as yet.

The AIIMS study suggests the 'delta' variant - which others, including one by British health authorities, say is between 40 and 50 per cent more infectious than the 'alpha' version first reported from the UK - is likely behind the majority of breakthrough infections in India.

The AIIMS-IGIB (Institute of Genomics and Integrative Biology) study was based on an analysis of 63 symptomatic patients who reported to the hospital's emergency ward complaining of high fever persisting for five to seven days.

Of these 63 people, 53 had been given at least one dose of Covaxin and the rest at least one dose of Covishield. Thirty-six had received both doses of one of these vaccines.

As many as 76.9 per cent of infections by the 'delta' variant were recorded in people who had received a single dose, and 60 per cent in people who had received both doses.

Data from the NCDC-IGIB study indicated that breakthrough infections due to the 'delta' variant seemed to affect people who took Covishield.

This study showed 'delta' breakthrough infections in 27 patients who had taken that vaccine, with the infection rate at 70.3 per cent.

Data from both studies indicated the 'alpha' variant is also proving resistant to Covishield and Covaxin, but not as significantly as the version first reported from India.

Both studies also indicated that while the vaccine's protection against the 'delta', and even 'alpha', variants may be reduced, severity of infection in each case appeared to be unaffected as a result.

This is in line with scientists' views that there is, as yet, no evidence the 'delta' variant is causing a greater number of Covid-linked deaths or more severe infections.

The AIIMS-IGIB and NCDC-IGIB studies, however, appear to contradict a joint investigation by the National Institute of Virology in Pune, the ICMR and Covaxin manufacturers Bharat Biotech. That study, which has also not yet been peer-reviewed, indicated Covaxin offers protection against both the 'delta' and 'beta' variants. The 'beta' variant was first discovered in South Africa.