According to tests conducted by the Indian Council for Medical Research’s regional medical research centre (RMRC) in Dibrugarh, a woman doctor in Assam was infected with two distinct strains of the Sars-Cov-2 virus at the same time.

Despite being completely vaccinated, the doctor became sick with the virus’s Alpha and Delta versions a month after receiving the second dosage. She experienced minor symptoms and was able to recover without the need for hospitalisation.

“A double infection happens when two variants infect one person simultaneously or within a very short period of time. It occurs when someone gets infected with one variant, but gets re-infected with another variant within 2-3 days of the first infection and before antibodies could develop,” said Dr B J Borkakoty, senior scientist at RMRC. He said that during the initial phase of the second wave in Assam around February-March this year, most Covid-19 cases were due to the Alpha variant. Then after the assembly elections in April, cases of Delta variant infections started to emerge.

The RMRC lab detected the double infection in the doctor in early May. The woman’s husband, also a doctor, was infected by the Alpha variant.

“While it is very common to get cases of infection with lineage A and reinfection with lineage B, there have also been quite a few cases seen of infection with lineage A + B,” Dr Anurag Agarwal, director, CSIR-IGIB in Delhi, said.