Second bouts of COVID-19 are uncommon, although folks 65 years and older could also be at increased danger of reinfection than youthful ones, a research from Denmark suggests.
The primary documented coronavirus reinfection was reported in August 2020, instantly sparking questions over how widespread such circumstances is perhaps (SN: 8/24/20). Research in well being care employees, a bunch at excessive danger of publicity to the coronavirus, counsel that beforehand contaminated persons are protected for a minimum of 5 months after their first spherical of COVID-19. However reinfection charges in broader communities have been much less clear.
Of 11,068 individuals who examined optimistic for the coronavirus throughout Denmark’s first COVID-19 surge from March to Could 2020, solely 72, or 0.65 p.c, examined optimistic just a few months later throughout one other wave of infections that started in September, researchers report March 17 within the Lancet. However of greater than 514,000 individuals who examined unfavourable within the spring, 16,819, or 3.27 p.c, have been contaminated in the course of the fall surge.
Join e-mail updates on the newest coronavirus information and researchBased on these charges, a earlier an infection presents round 80 p.c safety from a second an infection for folks beneath age 65. What’s extra, there was no signal that the immunity waned over greater than six months. However that stage of immunity drops to 47 p.c for people 65 years and older, the workforce discovered.
The research was carried out earlier than extra contagious coronavirus variants swept by Denmark. It’s nonetheless unclear how protecting immune responses from prior infections is perhaps in opposition to these variants. Some variants might evade the immune responses sparked by earlier infections or vaccines, decreasing the edge for reinfection for these viruses (SN: 2/5/21).
The findings and uncertainties over variants imply that even individuals who have already recovered from COVID-19, and notably those that are older, ought to get vaccinated to spice up current immunity, the researchers write.
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