Most people are protected against the Covid-19 reinfection for at least six months, but elderly patients are more likely to be infected by the virus a second time, researchers reported on Thursday.
An assessment of reinfection rates in Denmark last year showed that just over half a percent of people who tested positive for Covid-19 during the first wave from March to May did so again during the second wave, from September to December. The researchers found that initial infection with Covid-19 was likely to provide 80 percent protection from reinfection among under-65s, but that dropped to just 47 percent in older people. Free PCR testing is available to anyone in Denmark regardless of symptoms which is acting as the a pillar of national strategy for controlling Covid-19. More than two-thirds of the population, some four million people were tested in 2020. The rate of infection was five times higher for people who tested negative during the spike of the virus and then positive during the second wave. Of the over 9,000 people aged under 65 who tested positive in the first wave, just 55 percent tested positive again during the second wave.