Hugo Boserup, 22, is being tested for coronavirus by PCR as the global outbreak of coronavirus disease (COVID-19) continues in Malibu, California, on December 2, 2020.
Lucy Nicholson | Reuters
LONDON – Most people who have had Covid-19 are protected from taking it again for at least six months, but elderly patients are more prone to reinfection, according to a peer-reviewed study published in The Lancet medical journal Wednesday evening.
The first large-scale study on coronavirus reinfection rates was conducted in Denmark in 2020, with the findings confirming that only a small proportion of people (0.65%) returned a PCR test twice. positive. PCR tests are considered the gold standard and tell you if you currently have the virus.
However, while the previous infection gave 80-year-olds 80% protection against reinfection, it only gave 47% protection to people aged 65 and over, indicating that they are more likely to take Covid again. -19.
The authors of the study, which was conducted by researchers from the Staten Serum Institute and the University of Copenhagen in Denmark, and the European Center for Disease Prevention and Control in Sweden, and who did not receive funding, did not find no evidence that protection against reinfection decreased within a six-month follow-up period.
The Lancet noted that the researchers’ findings validate strategies that have prioritized the protection of the elderly during the pandemic, such as increasing social distancing and prioritizing vaccines, even for those who have recovered from the pandemic. Covid-19.
“The analysis also suggests that people who have had the virus should still be vaccinated, as natural protection cannot be relied on, especially among the elderly,” The Lancet said in a press release on Wednesday.
To date, the coronavirus pandemic has caused more than 120 million infections and more than 2.6 million deaths, according to Johns Hopkins University.
Although there have been previous studies suggesting that immunity to Covid-19, after a previous infection, could last at least six months, this latest research gives a better indication of the level of protection and the difference between groups of Covid-19. age.
Commenting on the study, Dr Steen Ethelberg of the Statens Serum Institute in Denmark said the research supported previous findings around reinfection rates.
“Our study confirms what a number of others seemed to suggest: Covid-19 reinfection is rare in young, healthy people, but older people have a higher risk of catching it again. Since older people also they are more likely to suffer from severe symptoms of the disease and, unfortunately, we die, our findings clearly show the importance of implementing policies to protect the elderly during the pandemic. “
The study was carried out by researchers who analyzed the data collected as part of Denmark’s national coronavirus testing strategy, through which more than two-thirds of the population was tested (69%, around 4 million people) by 2020.
The national free PCR test, open to everyone, regardless of symptoms, is one of the central pillars of Denmark’s strategy to control the spread of the virus.
The researchers used this data, which covers the country’s first and second wave of infections last year, to estimate protection against repeated infection with the original Covid-19 strain. Positive and negative test result ratios were calculated taking into account age, sex, and time differences since infection, and were used to produce estimates of protection against reinfection, The Lancet noted.
Additional studies are needed
It is important to note that the authors note that the time period of their study meant that it was not possible to estimate protection against reinfection with new variants of the virus that emerged late last year. The variant discovered in the UK has since become a dominant strain in Europe, for example, as it is more transmissible.
Additional studies are needed to assess how protection against repeated infection may vary by different strains of the virus, the medical journal noted.