According to research conducted by the University of Zurich, an exposure to harmless coronaviruses may enhance immunity from SARS-CoV-2. The results of the study published in ‘Nature Communications Journal’ has demonstrated that people with strong immune response to other human coronaviruses also have some protection against SARS-CoV-2 infection. 

The study authors also showed that individuals infected with SARS-CoV-2 had lower levels of antibodies against coronaviruses that causes common colds compared to those who are not infected. Besides, individuals with high concentration of antibodies against harmless coronaviruses had lesser chance of hospitalization after getting infected with SARS-CoV-2. 

It was also seen that cross-reactivity reduces the severity of infection. This is also supported by the fact that cross-reactive protection is based on both antibodies and also on T-cells. 

(ET Healthworld. ANI. November 24, 2021.

https://health.economictimes.indiatimes.com/news/industry/research-finds-exposure-to-harmless-coronaviruses-increases-immunity/87879028)