Why vaccinated healthcare workers are testing positive for COVID-19

A healthcare worker receives a dose of a COVID-19 vaccine in Kolkata. Rupak De Chowdhuri / Reuters
25 March, 2021

On 14 March, more than a month after he received the second dose of a COVID-19 vaccine, 55-year-old Rajinder Verma tested positive for the disease. Two days earlier, Verma had developed a fever, a slight cold and a cough. “I am not that young anymore, so I thought I was just exhausted and developed a cold due to the changing season,” he said. However, his temperature rose within a day to 103 degrees Fahrenheit and his body ached. “It was like I was on fire from the inside,” he told me. 

Verma worked as a security guard at the Government Medical College in Chandigarh. As a staff member of a healthcare institution, he had been vaccinated with his first dose on 16 January and the second booster dose on 13 February. “Never in a million years did I imagine I would test positive,” he said.  “Not after that vaccine for sure. No one even told us it's possible to test positive after getting vaccinated.”

What Verma did not realise is that it is possible to get infected after being fully vaccinated. The first reason is that it takes roughly 45 days after the first shot to develop immunity. The second is that the COVID-19 vaccines in use prevent severe disease but not infection. Many healthcare workers and frontline workers across the country have tested positive for COVID-19, even after getting the two vaccine doses prescribed. Healthcare workers got one of two vaccines currently available in India—Serum Institute of India’s Covishield or Bharat Biotech’s Covaxin. In Maharashtra, the state with the highest number of COVID-19 infections, at least eight healthcare workers tested positive after getting vaccinated. Healthcare workers in Madhya PradeshGujarat and Punjab have also tested positive for the disease after vaccination.

“Full immunity that also induces a sufficiently long-lasting immune memory takes about 15 days after the booster or second dose,” Dr Shahid Jameel, a virologist and the director of the Trivedi School of Biosciences at Ashoka University, said. For healthcare workers, who were the first group of people to be vaccinated, the second dose was administered about 28 days after the first. This meant that each healthcare worker was likely to develop lasting immunity only 45 days after the first dose.