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The Frontline Healthcare Worker’s Risk
By Nana Dadzie Ghansah
In the times we live in, one may ask, “Compared to the general population, what is the risk a frontline healthcare worker (HCW) has of contracting COVID-19?”
If one calculated this risk, it would be a ratio:
Risk of contracting COVID-19 in the general population: Risk of contracting COVID-19 as a frontline worker.
The risk in the group with very low risk is usually 1. That of the high-risk group is then calculated.
This ratio is called the “hazards ratio” (HR) and is a part of the branch of statistics called “Survival Analysis.” This branch entails a set of statistical methods used to investigate the time and probability it takes for an event of interest to occur (the hazard function) as well as the time and probability of the event not occurring (survivor function). In this case, the event would be “Contracting COVID-19.” Since we are interested in whether it occurs, we will structure a study that would allow us to calculate the hazards ratio.
Besides stating the hazard ratio, a value called the “Confidence Interval — CI” is also stated. The hazard ratio is often stated this way: Adjusted Hazard Ratio 11·61, 95% CI 10·93–12·33. A CI of 95% means that in 95% of the cohort, the calculated hazard ratios were between 10.93 and…
