Reports that fully vaccinated people have become infected with Covid-19 in India have concerned some scientists, reigniting the debate over the threat the mutating virus poses to global vaccination campaigns.

Ravi Gupta, professor of clinical microbiology at Cambridge university and one of the leading scientists investigating new strains of Sars-Cov-2, told the Financial Times he had identified “worrying” cases of post-vaccination infection involving at least one of the new variants first identified in India — B.1.617.2

At one care home in Delhi, 33 staff members who had been fully vaccinated with the Oxford/AstraZeneca jab, tested positive for the B.1.617.2 strain, he said, though none became seriously ill. “We thought everyone would be protected [but] the virus was able to get around the vaccine,” Gupta said.