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Current Affairs

Immunity development in body

Date: 17 July 2020 Tags: Miscellaneous

Issue

A longitudinal study by the researchers from King’s College London has suggested that immunity to Covid-19 might be lost in months.

 

Background

  in patients’ antibody levels three months after the infection that was observed.

 

 

Details

  • The researchers analysed the immune response of 90 recovered Covid-19 patients and healthcare workers. In their study, they found that antibodies that specifically help in neutralising the coronavirus SARS-CoV-2 decreased 2-23-fold during an 18-65 day follow-up period.

  • They suggested that immunity developed by the formation of antibodies against SARS-CoV-2 lasts only a few months, and recovered Covid-19 patients are likely to remain susceptible and could get re-infected.

  • The analysis found “a potent” level of antibodies produced in 60% of participants during the peak of their infection and that only 16.7% retained that level of potency 65 days later.

  • While the level of antibodies was at a higher level in patients with severe symptoms, it is not clear why antibody response correlates with disease severity. They also noted that asymptomatic individuals also generate antibodies against the virus.

  • The study has important implications when considering widespread serological testing, antibody protection against re-infection with SARS-CoV-2, and the durability of vaccine protection.

  • The antibodies usually remain in the blood for a period of time and quickly activate the immune system when the body is exposed to the pathogen again.

  • Some antibodies not only recognise when the pathogen returns, but also protect the body for a lifetime from re-infection, as in the case of measles.

  • In the case of the novel coronavirus, it is not yet clear how long the antibodies provide recovered person protection. Further studies are needed to determine the longevity of the antibody response and what level of antibodies is required to protect against re-infection.

  • A human body has two mechanisms of immunity response within the adaptive immune system. First is the humeral immune, which is also called antibody-mediated immunity and has been discussed above.

  • However, when a virus enters a cell and can no longer be detected by antibody-mediated immunity, a cell-mediated immune response can take over to kill the virus.

  • Cellular immunity occurs inside the infected cell, and are mediated by cells called T lymphocytes. These are the T cells, which recognise the infected cell.

  • Once the T cells are activated, they clone themselves generating numerous T cells, and destroy the infected cells.