Vaccinated persons infected with Delta variant less likely to have severe illness: Study

The Delta variant (B.1.617.2) has the potential to infect both the vaccination individuals and those who haven't been inoculated, a new study revealed on Monday. However, it found that the proportion of patients progressing to severe illness and mortality was lower in the vaccinated group. Approved by the Institutional Ethics Committee of ICMR-National Institute of Epidemiology, this study enrolled 539 out of the 3790 COVID-19 patients who visited triage centres in Chennai between May 3 and 7 when the second wave was at its peak.

This included 354 vaccinated persons out of which 241 had taken dose while 113 were inoculated and 185 unvaccinated individuals. The article published in the Journal of Infection stated, "Delta variant was the dominant circulating strain and one of the primary drivers for the second wave of SARS-CoV-2 in India. Studies have documented reduction in neutralization titres among Covishield and Covaxin recipients after infection with delta variant. This might be the reason for the breakthrough infections observed in the fully vaccinated individuals". 

The ICMR concluded, "B.1.617.2 has the potential to infect both the vaccinated and unvaccinated individuals. However, the progression of illness seems to be prevented by vaccination. Therefore, non-pharmaceutical interventions must continue to slow down the transmission. Additionally, the pace and scale of vaccination has to be increased to mitigate the further waves of the pandemic". 

COVID-19 vaccination in India

Apart from Covishield and Covaxin, the Drugs Controller General of India has approved Sputnik V, Moderna, and the Johnson & Johnson vaccine. From June 21 onwards, the Centre started procuring 75% of the vaccine stock and distributing it to the states for free. The vaccination drive is gaining pace with 13.45 crore jabs administered in July- a 12.5% increase against June's 11.96 crore inoculations. As per sources, 40 crore doses of COVID-19 vaccines will be available per month by October. 

This will be possible as a total of 7 vaccines are set to be available by October with Biological E's Corbevax, Zydus Cadila's DNA vaccine and Gennova's mRNA vaccine likely to get approval soon. The government has already hinted at vaccinating the entire adult population i.e nearly 90 crore people by December itself. In another development, the DCGI approved a study on mixing Covishield and Covaxin. This came after the ICMR observed in a preprint study that a combination of these COVID-19 vaccines elicited better safety and immunogenicity results than two doses of the same vaccine.

In this case, the Christian Medical College, Vellore will conduct the clinical trials on 300 healthy volunteers. The aim of this study will be to ascertain whether two different vaccine doses can be administered to a person instead of the current practice of administering two shots of the same vaccine. A total of 44,03,89,550 persons have been inoculated whereas 12,51,64,217 of them have received the second dose of the vaccine too.