The good people of Denmark have once again provided their excellent, centralized healthcare data to save us all, this time allowing researchers to track the COVID-19 infection rates of 4 million Danes last year, to see how many were infected twice. The results were published in The Lancet last week.
The study found that just 0.65% of people who tested positive for COVID-19 in the spring were reinfected later in the year. In context, this number is both surprisingly high and surprisingly low: It means that most people will not get reinfected—but when you factor in the country’s low 2% infection rate, it means that *of the Danes who are actually twice-exposed to COVID-19*, a surprising number of them become reinfected. Among young and middle aged Danes, their re-infection rate could be around 1 in 5—which is significant, if not alarming.
One group did display a rather low protective rate: people over age 65, who had only a 47% protection rate. “Natural protection, especially among older people, cannot be relied on,” wrote the researchers, who call for continued social distancing around people over age 65, as well as vaccinations.
Notably, protection against repeat infection continued for at least six months.