Real-world data on the Delta variant cases 

The Gupta Lab’s analysis also looked at breakthrough infections—those that happen despite being fully vaccinated—among healthcare workers at three hospitals in Delhi. The city was among the worst-hit during India’s second wave between March and June, and saw new infections go as high as 28,000 per day.

The analysis found that the Delta variant was most prevalent in these hospital “infection clusters,” and while overall breakthrough rates were low, each infected person spread the infection to two or more people. While other variants prevalent in Delhi had no such infection clusters of over two people among double vaccinated healthcare workers, there were 10 of these with Delta variant infections.

“…Vaccine breakthrough clusters amongst HCW [healthcare workers] is of concern given that hospitals frequently treat individuals who may have suboptimal immune responses to vaccination due to comorbidity,” the study noted. Such patients, it said, could be at risk for severe disease after an infection from healthcare or other staff in a hospital setting. “Therefore, strategies to boost vaccine responses against variants are warranted in HCW, and attention to infection control procedures should be continued even in the post vaccine era,” it said.

This research cements the worry that Delta is fitter against the body’s immunity, making its transmission much faster than other variants. On June 25, the World Health Organization (WHO) urged vaccinated people to continue wearing masks to protect against delta variant. Experts from WHO also confirmed that the delta variant is rapidly spreading among unvaccinated people.

The ICMR’s study from Odisha

In the eastern state of Odisha, an analysis of vaccinated healthcare workers showed that of the 274 breakthrough infections reported between March 1 and June 10, 83.9% of these were symptomatic. It is not clear yet what percentage of the total vaccinated healthcare workers were represented by these 274 cases.

This study was conducted by the Regional Medical Research Centre in Bhubaneswar, which is affiliated with the Indian government’s Indian Council for Medical Research, based on voluntary reporting from healthcare workers. The ICMR’s study, too, is in the preprint stages. Of those nearly 84% were symptomatic infections, 10% needed to be hospitalized, indicating that vaccines do work, but are not 100% protective against hospitalisation. Over 87% of the 274 received the Covishield vaccine.

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