- Diagnostics
- 2 min read
Re-infection threat high for 65+: Study
People over the age of 65 are at greater risk of catching Covid-19 again, with only 47% protection against repeat infection compared with 80% for younger people.
The researchers say these findings underline that measures to protect the elderly, including social distancing and vaccinations, are essential even if people have already been diagnosed with the viral infection.
The study, which is based on an analysis of the data collected as part of Denmark’s national Covid-19 strategy during the first and the second wave of the outbreak, also suggests that people who have had the virus should still be vaccinated, as natural protection – particularly among the elderly – cannot be relied upon.
“Our study confirms what a number of others appeared to suggest: reinfection with Covid-19 is rare in younger, healthy people, but the elderly people are at greater risk of catching it again. Since older people are also more likely to experience severe disease symptoms, and sadly die, our findings make clear how important it is to implement policies to protect the elderly during the pandemic,” Dr Steen Ethelberg, the lead author, said.
Why are the elderly people at higher risk of re-infection? The Danish researchers say it could be explained by natural age-related changes in the immune system of older adults. “These changes affect both the innate and adaptive immune system and coordination of immune responses, and hence result in older people being more susceptible to emerging infectious diseases such as SARS-CoV, MERS-CoV and other viruses,” they add.
“Further studies are needed to assess how protection against repeat infection might vary with different Covid-19 strains.”
In line with findings from other studies, the authors identified no evidence that protection against repeat infection with Covid-19 waned within six months. Because Covid-19 was only identified in December 2019, the period of protective immunity conferred by infection has still to be determined.
Dr Daniela Michlmayr from the Staten Serum Institut, Denmark said: “In our study, we did not identify anything to indicate that protection against reinfection declines within six months of having Covid-19.”
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