COVID-19 vaccination did not increase the risk of unexplained sudden deaths among young adults in India, according to a comprehensive study by the Indian Council of Medical Research (ICMR) on November 21.

The research, published in the Indian Journal of Medical Research, showed that lifestyle factors such as current smoking status, alcohol use frequency, recent binge drinking, recreational drug/substance use and vigorous-intensity activity were associated with unexplained sudden death.

As compared to never users, the more the frequency of alcohol use, the higher the odds for unexplained sudden death.

The research body undertook a multicentric matched case–control study in view of anecdotal reports of sudden unexplained deaths in India’s apparently healthy young adults, linked to COVID-19 infection or vaccination.

The researchers determined the factors associated with such deaths in individuals aged 18-45 years from 47 tertiary care hospitals across India.

At least 729 cases and 2,916 controls were included in the analysis.

The cases were apparently healthy individuals without any known co-morbidity, who suddenly (before 24 h of hospitalisation or seen apparently healthy 24 h before death) died of unexplained causes between October 1, 2021 and March 31, 2023.

"COVID-19 vaccination did not increase the risk of unexplained sudden death among young adults in India," revealed the researchers.

Instead "past COVID-19 hospitalisation, family history of sudden death and certain lifestyle behaviours increased the likelihood of unexplained sudden death", they added in the paper.

The study also showed that taking at least one dose of the COVID-19 vaccine lowered the odds of unexplained sudden death.

Patients with unexplained sudden death were four times more likely to have been hospitalised for COVID.

"Our findings did not indicate any evidence of a positive association of unexplained sudden death with COVID-19 vaccination. However, a history of sudden death in the family, COVID-19 hospitalisation and certain high-risk behavioural factors were positively associated with unexplained sudden death among young Indians," the researchers said.

"On the contrary, the present study documents that COVID-19 vaccination indeed reduced the risk of unexplained sudden death in this age group."