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.