Does the common cold protect against Covid?
People who experience common colds caused by coronaviruses are less likely to be infected with SARS-CoV-2, Nature Communications reports. The finding could lead to a universal vaccine against omicron and other SARS-CoV-2 variants.
The researchers included 52 people, aged between 23 and 49 years, exposed to Covid-19 by a household member. The study started in September 2020 so, at the time, most people in the UK had not been infected or vaccinated and omicron had not emerged. The researchers looked for T-cells specific for the spike and other SARS-CoV-2 epitopes (immune triggers) that cross-react with human endemic coronaviruses.
During the 28-day follow-up, 26 household contacts were positive on polymerase chain reaction for SARS-CoV-2. Levels of memory T cells that cross-react between SARS-CoV-2 and other coronaviruses and those targeting the nucleocapsid (an internal protein critical for viral replication) were higher in people who remained negative for SARS-CoV-2 than those who converted.
T-cells target internal viral proteins, rather than the spike. The authors comment that including internal proteins alongside the spike “could be critical in maintaining the benefit of vaccination in the case of vaccine strain mismatch, as could occur with the emergence of novel variants”.
- Around two in five Covid-19 infections are asymptomatic, according to a meta-analysis of 95 studies involving 29.8 million people. The risks of asymptomatic infections were highest among nursing home residents or staff, pregnant women, and air or cruise passengers.