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Covid-19 Reinfection

  • 03 Apr 2021
  • 5 min read

Why in News

A team of scientists from the Indian Council of Medical Research (ICMR) examined the cases of 1,300 individuals who had tested positive for the corona virus twice.

  • It was found that 58 cases of the 1,300 individuals or 4.5% could be classified as possible reinfections.

Key Points

  • Worldwide Cases of Reinfection:
    • The first confirmed case was reported from Hong Kong.
    • A couple of cases from the United States and Belgium also emerged.
    • However, there have been several cases of people testing positive for the virus multiple times, even in India, but not all such cases are considered reinfections.
      • Such cases are the result of what is called “persistent viral shedding”.

Persistent Viral Shedding

  • When an individual gets infected by a respiratory virus like SARS-CoV-2, the virus particles bind to the various types of viral receptor.
  • Thus, Recovered patients can sometimes continue to carry low levels of virus within their system for up to three months.
  • These levels are no longer enough to make the person sick or transmit the disease to others, but it can get detected in diagnostic tests.
  • The disease developed from such persistent virus is what is called Persistent viral shedding.
  • Significance of the Study of Reinfection:
    • It is crucial to make it clear whether a person who has been infected once develops permanent immunity against the disease, or can get reinfected after some time.
      • This understanding of the possibility of reinfection is crucial to the fight against the Covid-19 pandemic.
    • It will help decide the intervention strategies required to control the spread of the disease.
    • It will also help assess how long people would have to depend on masks and physical distancing.
    • It will have implications on the vaccination drive as well.
  • Determination of Reinfection:
    • Genome sequence analysis of the virus sample is done by scientists for conclusive proof of reinfection.
      • Because the virus mutates continuously, the genome sequences of the two samples would have some differences.
    • However, virus samples from every infected person are not being collected for genome analysis.
      • Therefore, in most of the cases there is usually no genome sequence from the previous infection to compare with.
    • Thus the scientists of ICMR looked at cases in which patients had reported positive results at least at the gap of 102 days. That would not include the disease from persistent viral shedding.
      • According to the Centers for Disease Control (CDC) in the USA, viral shedding continues until only about 90 days.
  • Symptoms in Reinfection:
    • The majority of the disinfectant patients remained asymptomatic during the intervening period, while few reported mild symptoms.
    • Some had symptoms such as intermittent fever, cough, or shortness of breath.
  • Implications of the Reinfection:
    • The scientists point out that permanent immunity cannot be assumed.
      • Reinfection might very well be happening and could be confirmed if it was possible to do genome analysis of every infected person.
    • If reinfection is the case the use of masks and social distancing would be a new normal.

Indian Council of Medical Research

  • Indian Council of Medical Research (ICMR) is the apex body in India for the formulation, coordination and promotion of biomedical research.
  • Its mandate is to conduct, coordinate and implement medical research for the benefit of the Society; translating medical innovations into products/processes and introducing them into the public health system.
  • It is funded by the Government of India through the Department of Health Research, Ministry of Health & Family Welfare.


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