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Researchers at the London School of Hygiene and Tropical Medicine have confirmed the existence of an “age gradient” in both infection rate and severity of symptoms of the novel coronavirus.
The scientists created models to imitate the pattern of infection in Wuhan, China, the site where the pandemic originated. they investigated three scenarios: age-dependent susceptibility to infection, the effect of age on the percentage of infected population that presents symptoms, or no effect of age on any aspect of infection. These models were compared to the infection data from China, Japan, Italy, Canada, South Korea and Singapore.
The researchers found that children and adolescents show a substantially lower infection rate, almost half of that of adults over 20 years-old. They also found that symptoms only appear in around twenty-one percent of infections in ten- to nineteen-year-olds, a low value compared to the sixty-nine percent estimate for infected patients over the age of seventy.
Public health interventions and policies to containing infections among children were found to produce little impact on a country’s Covid-19 infection rate. They also modelled these effects on countries with different age demographics, and found that “the expected per capita incidence of clinical cases would be lower [in countries with younger population structures].”