What we know — and don't know — about the coronavirus

Researchers continue delving into the coronavirus that struck China and is spreading globally will reach the dreaded pandemic stage.

The big question: Concern has been growing over whether the virus will spark a pandemic, which would likely kill multitudes and decimate economies. So far the outbreak is largely contained to China and hasn't spread from person-to-person consistently, Anthony Fauci of the National Institute of Allergy and Infectious Diseases tells Axios.

"Quite frankly, it is likely [to become a pandemic] given what we see happening in China. ... But, this is an unprecedented virus and we don't really know."

What they're saying: Tedros Adhanom Ghebreyesus, director-general of WHO, said Feb. 4 that 99% of cases are in China and it's not too late to contain it, but he urged nations to make "an immediate improvement in data sharing" from investigations of confirmed patients.

• WHO has only received complete case reports for 38% of cases outside China, and Tedros added, "Some high-income countries are well behind in sharing this vital data with WHO. I don’t think it’s because they lack capacity."

What we know: The new coronavirus' genetic sequence is 79.5% similar to SARS, another coronavirus that killed hundreds and devastated local economies in 2003.

• There have been 27 cases of human-to-human transmission of the new coronavirus in nine countries, per WHO's Oliver Morgan. U.S. public health officials have confirmed two secondary cases in America.
• Symptoms vary from mild illness with fever, cough, shortness of breath and sometimes diarrhea, to severe pneumonia, multiple organ failure and death, about seven to 10 days after symptoms start.

What we think we know:

• The virus is suspected to have originally emerged from bats, but there may also be intermediary hosts, or animals infected by bats that transmit to humans.
• The incubation period is 1–12.5 days, leading to a 14-day monitoring period for suspected cases, according to WHO's Maria Van Kerkhove.

• The WHO delegate from China said 75% of deaths were in people with one or more underlying health conditions.
• One person can infect roughly 1.4 to 4.9 people, per Kerkhove.
• The airborne droplets of the virus don't appear to last in the air as long as measles.

What we don't know: Scientists hope to find out if people without symptoms can transmit the virus, as this would likely tighten restrictions and increase the need for more diagnostics. WHO is investigating reports of this type of transmission happening.

• Fauci points out it's too early to determine the severity of illness until more data is provided. We don't yet know how deadly this virus will be.

Meanwhile, Tedros said 22 nations now have some type of travel restrictions imposed on people who had been in China, which has "little public health benefit." China's delegate said those nations should "stay clear of these criminal actions and stigmatization."

Go deeper: What's happening with the coronavirus

Editor's note: This piece was updated with new information.