Recent guidance issued by the U.S. Centers for Disease Control and Prevention sheds  new light on how coronavirus spreads through surfaces.

Though there is the possibility that coronavirus could be transmitted by touching a surface — and then your nose, mouth or eyes — the likelihood of that is lower than person-to-person contact, which is believed to be the primary way coronavirus is transmitted. 

“COVID-19 is a new disease and we are still learning about how it spreads,” says the CDC’s recently updated guidelines. 

Dr. Manisha Juthani, an infectious disease doctor and associate professor of medicine at Yale University, told USA TODAY that plenty of concern has been focused on packages and groceries during the coronavirus pandemic.

“The CDC guidelines I believe are trying to reduce fear and paranoia about methods of transmission,” she said.

From virus shelf life to susceptibility: What we know about the coronavirus keeps changing

More important, she says, is that “people MUST continue to maintain physical distance, wash hands, and try to avoid touching your face.” She also advises wearing masks, especially in crowded places.

“These habits will help going into the respiratory virus season this fall and winter.” 

This update may quell some major concerns about how COVID-19 is transmitted, but there are still plenty of questions lingering. Here’s what we know.

This is what we thought we knew about coronavirus on surfaces.

Most respiratory diseases, including COVID-19, do tend to last on surfaces, said Juthani.

Two major findings published within weeks of each were crucial in shaping what we thought we knew about coronavirus on surfaces.

A study published in the New England Journal of Medicine found that viable coronavirus could live on some surfaces, such as plastic and stainless steel, for three days, while surviving for up to 24 hours on cardboard.

Two weeks after this finding, a CDC report said that genetic material from coronavirus was found on surfaces in the Diamond Princess cruise ship 17 days after passengers left their cabins.

Neither of these studies confirmed whether coronavirus spread easily on surfaces. In fact, Joseph Vinetz, a professor of medicine at Yale and infectious disease researcher, said in March that the CDC report “has zero relevance to the ongoing epidemic.”

Out of an abundance of caution, however, frequently cleaning surfaces and washing hands became the norm whenever discussing coronavirus on surfaces.

How long does coronavirus live on surfaces?

Generally, the harder the surface, the longer the life of coronavirus.

Coronavirus can survive on glass for up to 96 hours, according to a study by the Journal of Hospital Infection published in January.

As stated earlier, coronavirus can last on plastic and stainless steel for 72 hours or three days, on cardboard for one day and on copper surfaces for 4 hours.

A visual guide: How long does the coronavirus live on surfaces?

Juthani notes that the process of a person getting infected with COVID-19 by touching a surface requires “the outer shell of the virus” to remain intact, which remains difficult with proper handwashing and surface cleaning.

“If surfaces are cleaned or even if you touch a contaminated surface but then wash your hands properly, the low risk of transmission from a contaminated surface becomes even lower risk,” Juthani told USA TODAY.

If I touch an area infected with coronavirus, will I get it?

Transmission through surfaces is much less likely than other forms of contact, the primary mode being person-to-person contact in an enclosed space for a long period of time, Juthani notes.

“If you wash your hands several times a day, particularly after handling objects that others could have touched, the risk of transmission is significantly lower from an already lower risk of transmission event,” she said.

The CDC points out that while chances aren’t high, the risk is still there.

“This is not thought to be the main way the virus spreads, but we are still learning more about this virus,” the CDC said.

Should I still be washing my hands after getting my packages or mail?

Yes.

The CDC has previously said that the likelihood of getting coronavirus from your packages from Amazon is highly unlikely “because of poor survivability of these coronaviruses on surfaces.” 

Still, Juthani cautions that proper hand washing is essential to preventing the spread of COVID-19.

“Although I want people to be less fearful and paranoid about surfaces,” she said, “this doesn’t change the need to wash hands after touching things, especially that have been outside of your household.”

Contributing: Jessica Flores, Doug Stanglin, Javier Zarracina and Adrianna Rodriguez, USA TODAY. Follow Joshua Bote on Twitter: @joshua_bote