Repeated infections with COVID-19 are rare in six months, but more common for people over 65, a new study found on Wednesday in the medical publication The Lancet found.
“People over 65 are at greater risk of contracting COVID-19 again, with only 47% protection against repeated infections compared to 80% for younger people,” said the authors.
Only 0.65% of patients tested positive twice, compared with 3.27% of those who tested positive after initially being negative.
“Protection against reinfection has remained stable for more than six months,” added the study.
The research is the first large-scale assessment of coronavirus reinfection.
It was conducted in Denmark during the first and second waves in 2020, based on data from national PCR tests (including 4 million people and 10.6 million tests).
Due to the timing of the study, the focus was on the strain of the original virus and the variants could not be included.
“More studies are needed to assess how protection against repeated infections can vary with different strains of COVID-19,” said The Lancet.
“Our findings make clear how important it is to implement policies to protect the elderly during the pandemic,” said Dr. Steen Ethelberg, of the Statens Serum Institut in Denmark.
The study also suggests that people who have had the virus, especially among the elderly, should still be vaccinated.