Can having a cold reduce the risk of COVID-19 infection? The truth is not necessarily that simple

Some studies in the past two years have found that the challenge posed by colds to the human immune system can cause us to produce some immune T cells that can more easily recognize the new coronavirus.

This may explain why some people who are exposed to the new coronavirus do not always become infected.

The British research team analyzed 52 close contacts of COVID-19 patients, all of whom were exposed to the virus because they lived with confirmed positive patients.

In the following days, nucleic acid tests showed that only half of them were infected, while the other half had not been infected.

After analyzing the blood immune cells of the two groups, it was found that those who were not infected had significantly higher levels of cross-reactive T cells. These T cells were induced by the previous cold. It is these T cells that have been shown to cross-react with the new coronavirus and can recognize the proteins of the new coronavirus.

The unexpected discovery is that these T cells target proteins inside the new coronavirus, rather than the surface spike proteins that many new coronavirus vaccines target. These internal proteins become new vaccine targets.

By targeting internal viral proteins, T cells can provide long-lasting protection because T cell responses last longer than antibody responses, which tend to wane within a few months after vaccination.

The vaccine targets the virus's "clothes", while this type of T cell targets the virus's internal proteins. Viruses can change their clothes frequently, but internal proteins are not easy to change, which is why this type of T cell can provide lasting immune protection for a longer period of time.

The Omicron variant is just a change of clothes, and it is possible that the immune system cannot recognize it, but the induced T cells are still possible, so don't be afraid of the cunning virus mutation.

Although having a cold can help you fight off the virus for a while, the best way to protect yourself from COVID-19 is still to be fully vaccinated, including booster shots.

If you haven’t gotten vaccinated, go get it now. Catching a cold is a good thing, as it is an immune exercise!

Rhia Kundu et al., (2022) Cross-reactive memory T cells associate with protection against SARS-CoV-2 infection in COVID-19 contacts. Nature Communications.