BOSTON (CBS) - Coronavirus is dominating headlines around the world and some of the scientific information out there can be confusing. WBZ-TV's Dr. Mallika Marshall answers some of those questions.

Q: Experts refer to both the "novel coronavirus" and something called COVID-19. Are they the same thing?

A: COVID-19 stands for "coronavirus disease 2019" and refers to the illness caused by this new coronavirus.

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Q: There has been some concern that screening has not captured as many people returning to the country as hoped.

A: Experts at the Harvard T.H. Chan School of Public Health say that traveler screening programs may miss up to two-thirds of infected travelers entering the U.S., which means there could be hundreds of people or more in the U.S. with the virus at this point. That said, while they initially estimated that up to 70-percent of adults could ultimately be infected by the virus, they are now downgrading that estimate to more like 20-to-60 percent based on indications that the virus may not be as transmissible as once thought. But honestly, these numbers and others like the fatality rate, are likely to change as time goes by.

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Q: Is it true that there may be two strains of the virus causing infections?

A: Researchers in China say they have discovered two strains of the new coronavirus. One called is "L," which they say is more easily passed from person-to-person and caused about 70-percent of early cases in Wuhan. The other strain is called "S" that caused the rest. They say the more transmissible strain "L" became less prevalent after early January.

Experts caution that these are preliminary reports and that it is still not clear which, if either, causes more severe disease, but it is common for viruses to change and mutate over time in order to survive.