Madhavi Bhatia, NIPER Guwahati
Coronavirus infection recovery provides a significant amount of immunity to individuals but there are some cases that have revealed that even after successfully recovering from COVID-19 infection there are chances of re-infection. This is mainly found to be due to mutation in the virus leading to different variants like alpha and beta among others. Immune responses following the infection vary among the individuals, it depends upon the severity of the first exposure, duration of infection. It is found that Alpha (B.1.1.7) first identified in U.K and beta (B.1.351) variant identified in South Africa are highly transmissible, there are chances that the infection is asymptomatic thus increasing the risk of hospitalization. However, mortality was found to be less in this case.
What can cause re-infection?
The possible reason for re-infection is the limited lifetime of the antibodies which is about 94 days after the first infection. The immune response varied drastically and it was observed that there was no evidence of immune memory 6 months after infection, thus the individuals did not have any neutralizing antibodies against alpha and beta variants.
A study was conducted by the University of Oxford along with the Universities of Liverpool, Sheffield, Newcastle, and Birmingham. They investigated immune responses in 78 health workers who were infected by the virus and were either symptomatic or asymptomatic. Along with them, 8 patients who were severely affected were taken for comparison to check the various elements of immune response blood samples were taken each month for about 6 months. Early immunological signatures were seen in the first month post-infection which may be associated with cellular and antibody immunity. After 6 months, most of the people who were symptomatic had measurable immune responses but 26 % did not. In the case of asymptomatic people, 92% did not have measurable immune responses.
It has been suggested that whether the first infection was symptomatic or asymptomatic, it is not necessary that it will protect people for the long term against Covid-19 infection, specifically against the new emerging variants. So it is necessary that we all follow the social distance norms, wear masks, and regularly sanitize our hands.
Also read:Vaccine for Covid positive HIV patients
Sources:
- Mustapha JO, Abdullahi IN, Ajagbe OO, Emeribe AU, Fasogbon SA, Onoja SO, Ugwu CE, Umeozuru CM, Ajayi FO, Tanko WN, Omosigho PO. Understanding the implications of SARS-CoV-2 re-infections on immune response milieu, laboratory tests and control measures against COVID-19. Heliyon. 2021 Jan 9:e05951. DOI: 10.1016/j.heliyon.2021.e05951
- https://www.indiatvnews.com/news/world/covid-survivors-still-at-reinfection-risk-from-alpha-beta-variants-713343
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