Vaccines effective in reducing mortality by 50% in Delta variant patients : CCMB

Hyderabad: Among the many concerns of the COVID-19 itself, there have been many new complications and variants being discovered very often leading to new new problems. The delta variant being the most infectious variant so far, a study has now revealed that taking the vaccine is helpful in fighting the deadly variant.

The severity of the COVID-19 disease among people infected with the Delta variant of coronavirus was significantly lower among vaccinated individuals, a study by researchers from Hyderabad-based Centre for Cellular and Molecular Biology (CCMB) and AIG (Asian Institute of Gastroenterology) Hospitals found.

“Severity of the disease (3.2% Vs 7.2%) and requirement of ventilatory support (2.8% Vs 5.9%) were significantly low in the vaccinated group despite the fact that these individuals had significantly higher age and risk factors,” the study said.

The rate of mortality was found to be about 50% lower in fully vaccinated individuals having a breakthrough infection (despite completing 14 days after the second dose). A breakthrough infection is when a fully vaccinated person tests positive for coronavirus. 

However, mortality in people who received a single dose was similar to the unvaccinated group, the study found. Preliminary results suggest that both Covishield and Covaxin have comparable efficacies in reducing the severity (ICU requirement at the time of admission) and mortality among patients infected with the Delta variant, the study said. 

The study, uploaded on the preprint server MedRxiv, observed clinical outcomes of 1,161 COVID-19 patients admitted to AIG Hospitals in Hyderabad between April 24 and May 31, 2021, at the height of the second wave of COVID-19 in India.

Of these, 495 patients were vaccinated with a single or double dose of either Covishield or Covaxin, while 666 patients were unvaccinated. More than  90% of patients in both vaccinated and unvaccinated groups were found to have been infected with the Delta variant (B.1.617.2) of SARS-CoV-2. Patients in the vaccinated group were of significantly higher age, and a higher number in this group had comorbid conditions. 

The study found a trend of increasing antibody levels and decreasing inflammatory markers in those who had received both vaccine doses compared with those who received a single dose. “Vaccinated individuals showed significantly higher neutralizing antibodies and lower inflammatory markers like serum Ferritin and Lactate Dehydrogenase, when compared to the unvaccinated group suggesting possible early neutralization of the virus and thereby prevention of aberrant inflammatory response,” the study found. 

Commenting on the lower mortality among fully vaccinated patients, the study said that the results “become even more significant in the light of higher comorbidities and age in the vaccinated group. Majority of deceased in completely and partially vaccinated individuals had no/minimal antibody response which was comparable to unvaccinated individuals. Strategies targeting these non-responders to vaccination like additional booster doses or change of vaccine type need to be explored further.”