COVID-19 reinfection rare, severe illness even rarer – CBS Miami

MIAMI (CNN) – When people were re-infected with COVID-19, their chances of ending up in hospital or dying were 90% lower than an initial infection with COVID-19, according to a new study.

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

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The first wave of infections in Qatar struck between March and June 2020. In the end, around 40% of the population had detectable antibodies against COVID-19. The country then experienced two more waves from January to May 2021. This was before the more infectious delta variant.

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

The researchers found that among the remaining cases, there were 1,304 re-infections. The median time from first illness to reinfection was approximately 9 months.

Among those re-infected, there were only four cases severe enough that they had to go to hospital. There have been no instances where people were sick enough to need treatment in the intensive care unit. Of 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 re-infections among that many people and four cases of serious illness, it’s quite remarkable,” said John Alcorn, an immunology expert and professor of pediatrics at the University of Pittsburgh who was not not affiliated with this study.

The study has limits. This was done in Qatar, so it is not clear whether the virus would behave the same elsewhere. The work was done when the alpha and beta variants were the source of many re-infections. There were 621 cases where it was undetermined and 213 of a “wild type” virus. There was no mention of the delta variant, which is now the predominant strain. This could have an impact on the number of re-infections.

Previous studies have shown that natural immunity reduces the risk of infection. A study made in Denmark published in March found that most people with COVID-19 appeared to have protection against reinfection that remained stable for more than six months, but a check of demographics on people who were re-infected showed that they were mainly people aged 65 and over. This study does not specify how long the protection lasts, nor does the new Qatar study.

Alcorn’s own research into natural immunity shows that antibody levels also vary widely from person to person. Scientists still don’t know what level of antibodies is protective, but in some cases the levels after infection may not be enough to keep a person from getting sick again.

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“It needs to be determined whether such protection against severe disease upon reinfection lasts longer, analogous to the immunity that develops against other ‘common cold’ seasonal coronaviruses, which elicit short-term immunity to a disease. mild reinfection but longer term immunity to more severe disease with reinfection, ”the study said. “If this were the case with SARS-CoV-2, the virus (or at least the variants studied to date) could adopt a milder infection pattern when it becomes endemic. “

Dr Kami Kim, an infectious disease specialist who is not affiliated with this study, said people need to be careful not to get the false impression that this means people don’t need to be vaccinated. ‘they got sick with COVID. -19.

“It’s like asking the question: do you need airbags and seat belts? Said Kim, director of the division of infectious diseases and international medicine at the University of South Florida. “Just because you have airbags doesn’t mean seat belts won’t help you and vice versa. It’s good to have the protection of both.

Kim said it wasn’t worth taking your chances with the disease, especially since an infection could lead to long-term effects. “The incidence of long Covid is much higher than the risk of getting the vaccine,” Kim said.

Moreover, vaccinations not only protect an individual against disease, they protect the community.

“Modern medicine is much better, and people get cancer and survive, as well as autoimmune diseases and thrive. Unless you’re very close, you don’t always know who is vulnerable to more serious illness, and you could literally endanger your loved ones if you get sick and put them at risk, ”Kim said. “Without vaccination, you cannot resume a normal life.

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

Alcorn said there was another important lesson from this study.

“Vaccines are still our best way to get to the same place as these people who have been infected, absolutely,” said Alcorn. “The main takeaway from this study here is that there is hope that through vaccination and healing from the infection, we will reach the level where everyone has some level of protection.”

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