Protection against a second COVID-19 infection

Lack of immunity to the virus that causes COVID-19 may cause the rapid spread of the virus around the world and the continuing pandemic. Previous research suggests that after a COVID-19 infection, a person’s immune system could protect against a second infection for at least 5 to 6 months. These studies also suggest that reinfection is rare, affecting less than 1% of individuals who have had a previous COVID-19 infection.This means that very few people who have had COVID-19 got it again within 6 months, because having it the first time made their bodies immune to it.

COVID-19 in Denmark

Now researchers from Denmark have studied almost 70% of the population (4 million people) who have had repeated COVID-19 tests after a second wave. The study showed that less than 1% of people who tested positive at the beginning of the pandemic had a second infection later in the year. Protection against repeat infection was more than 80%. However, people over 65 years of age had less protection (only 47%) against a second COVID-19 infection. There was no difference between men and women.

We all need the vaccine

These results suggest that after a COVID-19 infection, most people have protective immunity for at least 6 months. However, older people have lower levels of protection. So, while everyone needs the vaccine regardless of whether we have had COVID-19, it is especially important that people over the age of 65 be vaccinated. We still need more research to find out how long the vaccine gives protection, especially in older adults.


Photo by Mufid Majnun at Unsplash