Separate studies by the All India Institute of Medical Sciences (AIIMS), Delhi, and the National Centre for Disease Control (NCDC) revealed that the 'delta' variant is capable of infecting people even after they have received both doses of the Covaxin or Covishield vaccines. The studies, however, have not been peer-reviewed as yet.
The AIIMS study apparently shows that the 'delta' variant – which many sources say is about 40 and 50 percent more infectious than the 'alpha' version first reported from the UK – is possibly the reason behind the majority of breakthrough infections in India.
The AIIMS study, done in conjunction with the Institute of Genomics and Integrative Biology (IGIB), was carried out on 63 subjects who had breakthrough infections – 36 of whom had received two doses, while 27 had gotten one dose of vaccine. Of the 63 subjects, 10 had received Covaxin, and 53 had received Covishield doses. 51 were males, 22 were females, reported Zee News.
According to sources, 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.
The study also stated that while no deaths were reported in the 63 subjects, but almost all cases reported high-grade unremitting fever for 5-7 days.
As per the data from the NCDC-IGIB study as quoted in media reports, the breakthrough infections because of the 'delta' variant seemed to affect people who took Covishield. According to this study, the 'delta' breakthrough infections were seen in 27 patients who had taken that vaccine, with the infection rate at 70.3 per cent.
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.
So how worried should you be? It is important to also note that the AIIMS-IGIB and NCDC-IGIB studies seem to contradict previous studies. Recently, a joint investigation by the National Institute of Virology in Pune, the ICMR and Bharat Biotech, also not yet peer-reviewed, indicated Covaxin offers protection against both the 'delta' and 'beta' variants, the latter being first discovered in South Africa. Several studies earlier have also mentioned that even if people contract the virus post-vaccination, the severity of the disease is often reduced.