Vaccines reduce ‘Delta’ severity: Study

The rate of mortality was found to be about 50% lower in fully vaccinated individuals having a breakthrough infection, according to CCMB, AIg study

Hyderabad: For the first time, a Hyderabad-based study on the clinical outcomes of hospitalised breakthrough Covid infections has indicated that vaccines indeed helped in reducing severity and requirement for ventilator support among patients who tested positive for the Delta variant of SARS-CoV-2.

The hospital-based cohort study, which was a collaborative effort of the Centre for Cellular and Molecular Biology (CCMB) and Asian Institute of Gastroenterology (AIG), Hospitals, analysed clinical profiles and outcomes of 1,161 Covid patients between April 24 and May, when the second Covid wave was at its peak.

The study, which is available in the preprint form, included 1,161 Covid positive patients of which 495 patients were vaccinated either with Covaxin or Covishield while the remaining 666 patients were unvaccinated.

“Viral genome sequencing revealed that more than 90% of the patients in both the vaccinated and unvaccinated groups were harbouring the Delta variant of SARS-CoV-2. Vaccinated individuals showed higher neutralising antibodies and significantly decreased levels of Ferritin when compared to the unvaccinated group,” the study said.

Ferritin is a blood protein, which stores iron. Among Covid positive patients, several studies associate higher levels of Ferritin to cytokine storm, which causes mortality among Covid positive patients. The CCMB-AIG study has indicated that among breakthrough cases, Ferritin is found in decreased levels when compared to those who were unvaccinated.

“Severity of the disease and requirement of ventilator support were also significantly low in the vaccinated group despite the fact that individuals belonged to a significantly higher age group and risk factor. The rate of mortality was found to be about 50% lower in fully vaccinated individuals having a breakthrough infection. However, mortality in people who received a single dose was similar to the unvaccinated group,” according to the CCMB-AIG study.

The cohort study demonstrated that both Covishield and Covaxin are effective in preventing disease severity and mortality against Delta variant in completely vaccinated hospitalised patients, the researchers concluded. The CCMB-AIG study comes days after the pan-India demographic analysis of breakthrough Covid-19 infections on 677 patients, taken up by the Indian Council of Medical Research (ICMR), which has indicated that Covid vaccines are the best bet to reduce severity and fatalities among Covid-19 patients. In the ICMR study, only 9.9% of the breakthrough cases needed hospitalisation and the mortality was just 0.4%.

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