Why Viruses Like SARS-CoV-2 Can Reinfect Us, Evade Immune Response

Key lies in how human antibodies target the same parts of the virus again and again

Artist's rendition of SARS-CoV-2 particles, slightly aglow like X-ray images, as Y-shaped antibodies cluster around one in attack
Illustration of antibodies surrounding a SARS-CoV-2 virus. Image: koto_feja/iStock/Getty Images Plus

At a glance:

  • Study unearths shared immune system architecture that causes different people to make similar antibodies that home in on the same region of a virus.
  • This suggests viruses can make tiny changes to that region to generate new variants that can escape people’s existing immunity.
  • Findings could inform COVID-19 treatments and vaccine design.

This article is part of Harvard Medical School’s continuing coverage of COVID-19.

The human body is capable of creating a vast, diverse repertoire of antibodies: immune proteins that find and flag invaders such as viruses.

Yet humans create antibodies that target the same viral regions again and again, according to a new study led by investigators from Harvard Medical School and Brigham and Women’s Hospital.

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This means that the generation of new antibodies is far from random and that a virus may be able to reinfect a population of previously immune hosts by changing a single one of its amino acids, the researchers found.

The team’s discoveries have implications for our understanding of immunity, durability of immune response, and public health and could inform the design of treatments and vaccines for SARS-CoV-2. The findings are published April 7 in Science.