Online Covid calculator will tell who must get vaccines first

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Researchers, including one of Indian origin, have developed a new online calculator for estimating the individual and community-level risk of dying from Covid-19. The study, published in the journal Nature Medicine, revealed that the calculator will be useful to public health authorities for assessing mortality risks in different communities, and for prioritizing certain groups for vaccination as Covid-19 vaccines become available.

The algorithm underlying the calculator uses information from existing large studies to estimate risk of Covid-19 mortality for individuals based on age, gender, sociodemographic factors and a variety of different health conditions.

The risk estimates apply to individuals in the general population who are currently uninfected and captures factors associated with both risks of future infection and complications after infection.

"Our calculator represents a more quantitative approach and should complement other proposed qualitative guidelines for determining individual and community risks and allocating vaccines," said study senior author Nilanjan Chatterjee from the Johns Hopkins Bloomberg School of Public Health in the US.

The calculator based on the model is available online for public health officials and interested individuals alike.

It enables a user to determine individual risk based on factors such as age, sex, race/ethnicity, and medical history and can be used to define risk for a group, such as for a particular community, corporation, or university, based on the mix of relevant factors that define the group.

In their paper, the research team used their calculator to describe the risk distribution for the whole US population, showing, for example, that only about four per cent of the population at high risk -- defined as five times greater risk than the US average -- is expected to contribute close to 50 per cent of the total deaths.

The researchers also showed that population-level risk varies considerably from city to city and county to county.

"For example, the percentage of the adult population exceeding the fivefold risk threshold varies from 0.4 per cent in Layton, Utah, to 10.7 per cent in Detroit, Michigan," Chatterjee said.

The calculator allows users to calculate the mortality risk of individuals by combining information on individual-level factors with community-level pandemic dynamics, as available from a large variety of forecasting models.

Thus, when a big wave of infections hits a population, the risk estimates for individuals will rise in that community.

Currently, the tool is updated on a weekly basis to incorporate information on state-level pandemic dynamics.