Researchers have now claimed that the age factor does not determine how prone people are to contracting coronavirus.
However, the development of symptoms, the progression of the disease, and mortality are age-dependent.
The research team from Hokkaido University in Japan, have modelled available data from Japan, Spain, and Italy to show that susceptibility to Covid-19 is independent on age. However, the occurrence of symptomatic Covid-19, severity, and mortality are likely dependent on age.
The study was published in the journal Scientific Reports.
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The authors wrote in their study: “Causes of mortality in elderly individuals may be due to two factors: how likely they are to be infected due to their advanced age, which is reflected in the number of cases; and, how likely they will be affected by a severe form of the disease due to their advanced age, which is reflected in the mortality rate.”
For the study, the researchers examined data from Italy, Spain, and Japan to determine if any relationship between age, susceptibility, and severity exists.
The researchers chose these countries as they have well recorded, publicly available data. As of May 2020, the mortality rate (number of deaths per 1,00,000) was 382.3 for Italy, 507.2 for Spain, and 13.2 for Japan.
The researchers found that despite the wide disparity in mortality rates, the age distribution of mortality (the proportional number of deaths per age group) was similar for these countries.
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The scientists developed a mathematical model to calculate susceptibility in each age group under different conditions.
They also considered human-to-human contact levels in each age group, as well as varying restriction levels for outside-home activities in the three countries.
The study noted: The age distribution of mortality from the novel coronavirus disease (Covid-19) suggests no large difference of susceptibility by age.