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Infectious Diseases

Updated 05 October 2020

Silent reinfection of healthcare workers a dangerous reality

A report on two Indian healthcare workers highlights the dangers of asymptomatic reinfection by Covid-19.

  • A case study report highlights two asymptomatic reinfections of Indian healthcare workers
  • It drives home the importance of continued Covid-19 surveillance in hospitals
  • Both were reinfected with a different strain compared to the first time 

Long-term immunity to Covid-19 has been questioned, based on reports of reinfections. And now a case study of two Indian healthcare workers are highlighting an even scarier notion – silent reinfection.

Published in Clinical Infectious Diseases, researchers report two unique cases where two asymptomatic healthcare workers were reinfected months later with a genetically different strain of the coronavirus – again without showing any symptoms.

This is the first time that scientists report reinfection cases where both infections presented no symptoms. In previous reports, symptoms showed up in either the first, second or both infections.

READ | Healthcare workers and Covid-19: Researchers looked at risk of transmission in a hospital setting

Case studies

The two healthcare workers' asymptomatic Covid-19 infections were detected in routine surveillance while working in Covid-19 wards in North India.

The 25-year-old man and 28-year-old woman were both first diagnosed in May. Despite showing no symptoms, they were hospitalised as per policy at the time.

They tested negative about 10 days later and returned to work. In August and September, respectively, they tested positive again, months after the first infection.

READ MORE | Three things scientists still need to learn about Covid-19 reinfections

Different strain

During their second infection, their viral load was, however, a lot higher, and the researchers could confirm that they were infected with a completely different strain of the virus.

This rules out the possibility of reactivation and potential leftover from the first strain. One of the genetic variants found in the woman also had a certain resistance to neutralising antibodies.

"The report highlights the possibility of undetected SARS-CoV-2 reinfections and the need for surveillance of SARS-CoV-2 reinfections in healthcare systems."

Healthcare workers have been at the forefront of the pandemic with higher infection rates than the general public, with asymptomatic spread a big concern as immunity is thought to be stronger in those with symptoms.