A new study suggests that pre-Covid-19 infections reduce the risk of contracting colds caused by milder coronaviruses, which could be key to developing broader Covid-19 vaccines.
"We believe there will be a coronavirus epidemic in the future ," said Dr. Manish Sagar, lead author of the study published Wednesday in the journal Science Translational Medicine . "Vaccines could be improved if we could replicate some of the immune responses provided by natural infection."
The study examined Covid-19 PCR tests of more than 4,900 people who consulted a doctor between November 2020 and October 2021. After taking into account factors such as age, sex, and pre-existing conditions, Dr. Manish Sagar said that he and his colleagues found that people previously infected with Covid-19 were about 50% less likely to have a symptomatic cold caused by the coronavirus, compared to people who were, at the time, fully vaccinated and had not yet been infected with Covid-19.
Several viruses cause colds; coronaviruses are thought to be responsible for about one in five colds.
Researchers have established a link between protection against colds caused by coronaviruses and virus-killing cellular responses to two specific viral proteins. These proteins are not used in most current vaccines, but the researchers propose adding them in the future.
"Our studies suggest that these could be new strategies for better vaccines that would target not only current coronaviruses, but also any other coronaviruses that may emerge in the future ," said Sagar of Boston Medical Center.
Dr. Wesley Long, a pathologist at Houston Methodist in Texas who was not involved in the study, said the findings should not be seen as an attack on current vaccines, which target the "spike" protein found on the surface of the SARS-CoV-2 virus, which causes Covid-19.
These vaccines, he said, "remain the best defense against severe Covid-19 infection, hospitalization and death" .
But he added: "If we can find targets that provide cross-protection between several viruses, we can either add them to specific vaccines or start using them as vaccine targets that would give us broader immunity from a single vaccination. That would be really great."
