Genetic infection from Covid-19 is rare, serious illness is even rarer, finds a study of people in Qatar

The study, published Wednesday in the New England Journal of Medicine, found that there were few confirmed re-infections among 353,326 people who received Covid-19 in Qatar, and the re-infections were rare and generally mild.

The first wave of infections in Qatar hit between March and June 2020. In the end, about 40% of the population had detectable antibodies to Covid-19. The country then had two more waves from January to May 2021. This was ahead of the more contagious delta variant.

To determine how many people were re-infected, researchers from Weill Cornell Medicine-Qatar compared the registrations of people with PCR-confirmed infections between February 2020 and April 2021. They excluded 87,547 people who received the vaccine.

Researchers found that among the remaining cases, there were 1,304 reinfections. The median time between the first disease and re-infection was about 9 months.

Among those with reinfections, there were only four cases that were serious enough that they had to be hospitalized. There were no cases where people were sick enough to be treated in the intensive care unit. Among the initial cases, 28 were considered critical. There were no deaths among the re-infected group, while there were seven deaths in the initial infections.

“When you only have 1,300 reinfections among so many people and four cases of serious illness, it’s pretty remarkable,” said John Alcorn, an expert in immunology and a professor of pediatrics at the University of Pittsburgh who was not associated with this study.

The study has limits. It was done in Qatar, so it is not clear if the virus would behave the same way elsewhere. The work was performed as the alpha and beta variant was the cause of many re-infections. There were 621 cases where it was indeterminate and 213 from a “wild-type” virus. There was no mention of the delta variant, which is now the dominant strain. It can affect the number of reinfections.

Previous studies have shown that natural immunity reduces the risk of infection. A study conducted in Denmark published in March showed that most people who had Covid-19 seemed to have protection against re-infection that remained stable for more than six months, but a check of the demographics of who became infected again, showed that it was mostly people 65 and older. That study does not make clear how long the protection lasts, nor does the new Qatar study.

Alcorn’s own research into natural immunity shows that antibody levels also vary significantly from person to person. Researchers still do not know what level of antibodies are protective, but in some cases levels after infection may not be enough to prevent someone from getting sick again.

“It must be determined whether such protection against serious disease by re-infection lasts for a longer period, analogous to the immunity developed against other seasonal ‘common colds’ coronavirus, which elicits short-term immunity to mild re-infection, but prolonged immunity to more serious disease with re-infection, “the study said. “If this were the case with SARS-CoV-2, the virus (or at least the variants studied to date) could assume a more benign pattern of infection when it becomes endemic.”

Dr. Kami Kim, a specialist in infectious diseases who is not affiliated with this study, said people should be careful not to get away with the wrong impression that it means people do not need to be vaccinated if they have been sick with Covid . -19.

“It’s like asking the question, do you need airbags and seat belts?” said Kim, director of the University of South Florida’s Division of Infectious Disease & International Medicine. “Just because you have airbags, does not mean that seat belts do not help you and vice versa. It is good to have protection for both.”

Kim said it is not worth taking your chances with the disease, especially because an infection can cause long-term effects. “The incidence of long-term Covid is far higher than the risk of getting a vaccine,” Kim said.

Vaccinations also not only protect a person from getting sick, it protects society.

“Modern medicine is much better, and people get cancer and survive and autoimmune diseases and thrive. Unless you are super close, you do not always know who is vulnerable to a more serious disease, and you can literally put people off, one cares, at risk, if you get sick and expose them, “Kim said. “Without vaccination, you can not return to a normal life.”

Limiting the number of diseases also limits the potential for more variants to develop, variants that could be even more dangerous than what is in circulation now.

Alcorn said there is another important lesson from this study.

“Vaccines are still our best method of getting to the same place that these people who have been infected absolutely are,” Alcorn said. “The most important thing about this study here is that there is hope that through vaccination and recovery from infections we will reach the level where everyone has a certain level of protection.”

.