Agence France-PresseMar 18, 2021 10:46:22 IST
Surviving Covid-19 protects most people against relapse for at least six months, but elderly patients are more likely to be lowered by the virus a second time. trip, researchers said Thursday. An evaluation of transplant rates in Denmark last year showed that just over half of the percent of people who tested positive for Covid in the first wave from March to May did so again during the second wave, from September to December. Among them, the researchers found that an original infection with Covid-19 was likely to provide 80 percent protection from relapse among children under 65, but that fell to just 47 percent in the elderly.
“We did not identify anything to show that protection against relapse declines within six months of being on Covid-19,” said Daniela Michlmayr, a researcher at the Staten Serum Institute in Denmark and co-author study in the Lancet.
Free PCR testing is available to anyone in Denmark regardless of the symptoms that has been a key pillar of the national strategy for controlling Covid-19.
More than two-thirds of the population – around four million people – were tested in 2020.
Ratios of positive and negative test results – taking into account differences in age, sex, and duration of disease – were used to make estimates of protection against recurrence.
The infection rate was five times higher for people who tested negative during the spring outbreak of the virus and then positive through the second wave.
Of the more than 9,000 people under the age of 65 who tested positive in the first wave, only 55 – or 0.6 per cent – tested positive again during the second wave.
This compared with 3.6 percent of people in this age group who tested positive through the second wave but not in the first.
Protecting the elderly
The researchers said this meant that the first Covid-19 infection was likely to provide 80 percent protection from relapse among children under 65.
For those over 65, however, the level of protection has dropped significantly.
Of the more than 1,900 over 65 who tested positive during the first wave, 17 (0.88 percent) tested positive again during the second.
This compared with 1,866 out of more than 90,000 over 65 (two per cent) who tested positive through the second wave but not the first – a protective difference of 47 per cent .
“Our study confirms what several others seemed to suggest: reinterpretation with Covid-19 is extremely rare in younger, healthier people,” said Steen Ethelberg of the Statens Serum Institute in Denmark.
“But the elderly are at greater risk of catching up again,” he said. “Our findings highlight the importance of implementing policies to protect older people during the pandemic. “
The researchers were unable to estimate protection against relapse with Covid-19 variants – some of them more diffuse – that did not appear until after the study period.
“Many will find the data … pretty scary,” said professors Rosemary J Boyton and Daniel M Altmann of Imperial College London in a comment, also in The Lancet. “Only 80 percent is protection from relapse overall, reducing to 47 percent in people age 65 and older, who are more concerned about figures than previous studies have offered.”
“All of this data is a testament, if needed, to SARS-CoV-2 that the prospect of immune protection against natural diseases may not be within our reach and a global vaccination program with high-efficacy vaccines is the lasting solution. , “they wrote.
Read also: Elderly people with hearing problems suffered from memory loss, loneliness during COVID-19 lockout