Delta variant behind most breakthrough infections: ICMR

A new study by the Indian Council of Medical research (ICMR) has found that 86.09% of the breakthrough Covid-19 infections in vaccinated people were caused by the Delta variant. The nationwide study also found that fatality was very low among individuals who get infected even after vaccination. While 9.8% of such people required hospitalisation, only 0.4% cases proved fatal.

“This clearly suggests that the vaccination does provide reduction in hospital admission and mortality,” the study said. It was observed that during the second wave while southern, western, eastern and northwestern regions of India predominantly reported “breakthrough infections from mainly Delta (B.1.617.2) and then the Kappa (B.1.617.1) variant”, it said.

ICMR collected 677 clinical samples of individuals who have been partially or fully vaccinated but got infected by Covid-19 from 17 states and union territories for the study. A total of 482 cases (71%) were symptomatic with one or more symptoms, while 29% had asymptomatic SARS-CoV-2 infection.


According to the findings of the study, fever (69%) was the most consistent presentation followed by body ache, including headache and nausea (56%), cough (45%), sore throat (37%), loss of smell and taste (22%), diarrhoea (6%), breathlessness (6%) and 1% had ocular irritation and redness.

Among the 677 Covid-19 positive individuals, 604 had received Covishield, 71 Covaxin and two received China's Sinopharm vaccine.

The study also noted that between March and June, there was “high community transmission” of the Delta variant of the infection, followed by Alpha and Kappa variants.

ICMR collected samples for the study from Maharashtra, Kerala, Gujarat, Uttarakhand, Karnataka, Manipur, Assam, Jammu and Kashmir, Chandigarh, Rajasthan, Madhya Pradesh, Punjab, Pondicherry, New Delhi, West Bengal, and Tamil Nadu.