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The study, conducted during the first two waves of the disease in Denmark, confirmed that only a small percentage (0.65%) of people had positive PCR tests in both waves of illness, while the number of people who tested positive after having a first negative test increased to 3.27%.
According to the researchers, These values translate into 80% protection against reinfection in people who contracted the disease in the last six months, but the protection among the population over 65 years tested is only 47%, which indicates that it is more susceptible to contract Covid-19. again.
The study authors found no evidence that protection against reinfection decreased within the six-month follow-up period.
Antenna 1
The conclusions of the study refer to the research article published in the journal Lancet, highlight the importance of measures to protect older people during the pandemic, such as social distance and priority access to vaccines, as well as suggesting that people who have already contracted the SARS-CoV-2 coronavirus, especially older people, also should be vaccinated.
Other recent studies have indicated that reinfections are rare and that immunity to Covid-19 can last for at least six months, but the degree of protection provided by contracting the disease against future reinfections remains poorly understood by researchers, says the publication.
“The results emphasize the importance of people adhering to the measures in place to keep themselves and others safe, even if they have already had Covid-19. Our findings may also support broader vaccination strategies and more flexible containment measures.“Said one of the study leaders, Steen Ethelberg, from the Statens Serum Institut.
The study authors analyzed data collected as part of Denmark’s national testing strategy for COVID-19, through which more than four million people were tested, that is, two-thirds of the population (69%). in 2020.
Some study time limitations
However, the authors note that the period in which the study was carried out did not allow to estimate the protection against reinfection with new variants of Covid-19 and that more studies are needed to understand how different strains can affect reinfection rates.
Still, another researcher involved in the study, Daniela Michlmayr, stressed that “nothing has been identified that indicates that protection against reinfection will decrease over a period of six months.”
“The relatively similar coronaviruses SARS and MERS have been shown to provide immune protection against reinfection for at least three years, but a long-term analysis of Covid-19 is needed to see its long-term effects on the likelihood of contracting the disease again. . .”, Highlighted the researcher.
Among the limitations of their own study, the authors note that it was not possible to assess whether the severity of Covid-19 symptoms influences the degree of protection against reinfection, since detailed clinical data are only collected in hospitalized patients.
In a comment related to the publication of this study, Professors Rosemary J. Boyton and Daniel M. Altmann, from Imperial College London, state that “compared to the more formal reports of reinfection cases” that make reinfection seem “a extremely rare event ”, The data presented is“ relatively alarming ”.
“Only 80% protection against reinfection in general, reduced to 47% in people aged 65 and over, are more worrying figures than those offered in previous studies. They confirm that, for SARS-CoV-2, the hope of group immunity through natural infections may not be within reach and that a global vaccination program with highly effective vaccines is the most durable solution.”The researchers concluded.
with agencies
