Chestnut Hill, Mass. (02/06/2020) - The first case of nCov-2019, more commonly known as coronavirus, was identified in Massachusetts over the weekend — Saturday, February 1st — and along with that infection came a barrage of news and social media posts full of data, terminology, and information that was difficult to understand. But what does all that information really mean? Check out the summary below by Connell School of Nursing Assistant Professor Nadia Abuelezam, Sc.D., to better understand the technical side of coronavirus, and learn how you can reduce risk.

Nadia Abuelezam

Connell School of Nursing Assistant Professor Nadia N. Abuelezam, Sc.D.

Incubation period: The incubation period is the time from infection to the start of symptoms. Currently the incubation period for coronavirus is estimated to be from 2-14 days. This means that someone who was infected could be symptom free for two weeks and not know they were infected. Even if someone feels healthy, they can still carry coronavirus for up to two weeks.

Latent period: The latent period is the time from infection to when a person can infect other people. If the latent period is shorter than the incubation period, this means that someone can spread the disease before they’ve developed symptoms. Little information is available about the latent period for coronavirus, while some initial reports suggested that the virus may spread before symptoms start this information has been shown to be false. The latent period is an important number for epidemiologists to know so they can help the public understand the risk of interacting with someone who may or may not be infectious.

Prevalence: Prevalence is usually presented as a percentage and usually gives a sense of the overall burden of disease in a particular area. Usually, a prevalence can be understood as the proportion of the population with the disease of interest. We have little information about the overall prevalence in China. Because the number of cases in the United States is low, the prevalence is currently negligible.

Incidence: Incidence is usually presented as a rate indicating the number of new cases occurring in a population over a certain period of time. Incidence gives you a sense of your risk, with a larger incidence representing greater risk. Incidence can only be calculated with more information on the total number of infections and the total population at risk. More information about incidence will be reported as the epidemic continues.

Take the same steps you would to help prevent a cold or the flu: Regularly wash hands with soap and warm water, cover coughs and sneezes, stay home if you're feeling sick.


Basic reproductive number: The basic reproductive number indicates the number of new cases one could expect from one infectious case. When the basic reproductive number is greater than 1, the disease is expected to spread. It’s important to note that the basic reproductive number is very context specific, so it cannot be extrapolated across populations and countries. The basic reproductive number in Wuhan, China (the epicenter of the epidemic) is currently estimated to be 2.68 (meaning 2-3 people are infected from every infected person in this particular area). (For context, the basic reproductive number for the flu is estimated at 1-2 and for measles 12-13.)

With data being collected and analyzed quickly from multiple sources all over the world, it is important to stay up to date with the newest information from reliable sources. It’s also important to keep in mind that information at the beginning of epidemics may not be as reliable as information that comes out later in an epidemic. That’s why it’s important to stay up to date and follow recommendations and guidelines from experts trained in public health.

For now, you can help reduce risk by taking the same steps you would to prevent a cold or the flu:

  • Regularly wash hands with soap and warm water
  • Cover coughs and sneezes
  • Stay home if you're feeling sick

And remember, more than anything at the beginning of an epidemic, including this one, it’s important to stay calm, stay healthy, and to contact your health care provider with any questions.