Immunity after Covid-19 protects re-infection for at least six months, according to a Danish study. Experts, on the other hand, believe that age has a role. People who have been infected with the coronavirus have a 180-day protective period after which they are considered immune to reinfection. Some people, on the other hand, have contracted the infection twice in a short period of time.
Zdenek Hel, an immunologist at the University of Alabama, points to a Danish study from 2020. The study found that recovering from Covid-19 protects 80 percent of patients from re-infection in the next eight months. However, the level of protection for seniors over 65 years old is below just 47 percent. This number can be further reduced by different variants of the virus, such as South African, Brazilian, or Indian mutations.
According to immunologist Helena Tlaskalova-Hogenova, a study conducted by the Czech State Medical Institute found that 28 patients out of 362,084 became ill again, with the majority of them having a mild first and second illness. After illness, the immune system responds not only with antibodies but also with a cellular reaction. Memory cells are generated, and when they come into touch with the virus again, they multiply, boosting cellular immunity and antibody resistance.
Helena Tlaskalova-Hogenova adds that people who have undergone coronavirus are protected in the same way as those who are vaccinated. However, she points out that it is still unknown how long protective immunity lasts after illness and vaccination.
According to a study recently published in the journal Science, vaccination with a single dose of the vaccine increased neutralizing antibody levels by one to a thousand times in people with coronavirus. These antibodies partially protect against aggressive variants of the virus. It is recommended that vaccination should be completed no earlier than 90 days after Covid-19 illness. This will increase the level of neutralizing antibodies and protection against possible infection.