COLUMBUS (WCMH) – Just how contagious is the COVID-19 coronavirus? A new study suggests it may be much more contagious than initially thought.

Ohio Department of Health Director Dr. Amy Acton explained it using something called R0, or “R-naught,” which is a clinical term that calculates the spread rate of a disease.

The initial R0 for COVID-19 was 2.3.

“Whenever that R0 is above 1, it means we’re exponentially growing it,” Acton said.

As an example, Acton said an R0 of 2 means at first, there are 100 people infected, but in as little as three days, there could be 200 people infected, and three days after that, up to 400 infected, growing exponentially.

If the R0 is less than 1, cases become exponentially less – 100 people may spread it to only 50 people, then to only 25 people, Acton said.

“That’s when we start to see a disease burn out or we break those chains of transmission,” she said.

The new study from China and published on the CDC website suggests the R0 for COVID-19 could be as high as 5.7, meaning the disease is highly contagious. It is unclear if the new study refers only to cases in China or if it can be applied elsewhere.

However, in Ohio, Acton said the R0 for the spread of the disease may be as low as 1.21, with her crediting the steps taken such as social distancing and the stay-at-home order as helping keep the spread down.

“We know those R-naughts are underestimates, but still, it shows that you in Ohio are slowing that spread,” she said.

According to the study, in order for herd immunity – in which a percentage of the population is immune from a disease, acting as a buffer for those who aren’t immune – to burn out the disease, a 5.7 R0 means 82 percent of the population must have some immunity – either through a vaccine or prior infection – to prevent spreading the disease, burning it out.

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