This transmission electron microscope image shows SARS-CoV-2, the virus that causes COVID-19. Isolated from a patient in the U.S., emerging from the surface of cells cultured in the lab. Credit: National Institute of Allergy and Infectious Diseases-Rocky Mountain Laboratories, NIH
All children are different but if there’s one thing parents everywhere can agree on it’s this: kids are germy. Between daycares and more formal schooling, children are frequent fliers when it comes to common cold infections. Yet, adults rarely “catch a cold.” Why is that?
According to a new study by scientists at La Jolla Institute for Immunology, it’s because adults have stable memory responses of common cold coronaviruses (CCCs)-fighting antibodies and T cells, presumably derived from these multiple exposures to CCCs in childhood.
There’s no reason to think this type of immunity can’t be reached with SARS-CoV-2, the researchers say, especially since we already have a blueprint. And while the rise of new SARS-CoV-2 variants do complicate the process, this research shows it’s more a matter of when than if.
"At this stage of the pandemic, we're still mounting that immunity to SARS-CoV-2," said Ricardo Da Silva Antunes, co-leader of the study and instructor at La Jolla Institute for Immunology (LIJ).
"[That’s why] it’s really important to get the vaccine boosters—the third and fourth doses," adds the other leader of the research, Alessandro Sette.
Immunity then and now
For the study, published in Cell Host & Microbe, the researchers analyzed blood samples taken pre-pandemic from 32 participants aged 18 to 35.
Working off the safe assumption that the young adults had been exposed to CCC multiple times as children, the researchers found that adults have stable immune memory and tend to catch CCCs only about every eight years.
“The immune response is remarkably stable and durable, over time," said Da Silva Antunes.
SARS-CoV-2 is different from CCCs, but they have many structural similarities, and previous work at LJI suggests the immune system recognizes similarities between different coronaviruses. In this research, the LJI scientists showed that antibodies and T cells from the group of healthy adults could cross-react with SARS-CoV-2. This cross-reactivity may actually help protect a person from severe COVID-19, and the finding reinforces the idea that the immune system sees CCCs and SARS-CoV-2 in a similar way.
If the pattern seen in CCC immunity holds true for SARS-CoV-2, as more immunity builds in the population, reinfections should become less frequent over time and COVID-19 symptoms should be less severe.
Based on the data, both researchers agree that the best strategy right now is for people to stay up-to-date on their booster shots as the ones available today “may be critical for long-term immunity.”