What the best public health minds know — and don’t know — about Wuhan coronavirus

How soon could there be a cure, diagnostic tests, or a vaccine?

The CDC has already created a diagnostic test, although public health officials are working on faster tests that can be widely disseminated to hospitals so patients can be rapidly diagnosed. Fauci said a vaccine could start human trials in as little as three months, but that’s just the first step in a longer journey to establishing that the vaccine is safe and effective. He noted that it’s possible the outbreak could end before a vaccine is available, but “we are proceeding as if we will have to deploy a vaccine.”

New drugs will take longer to develop, although there are already studies underway based on drugs that were tested earlier for SARS and MERS, which are also coronaviruses. Other compounds are being screened to see if they can target this virus. (There are drugs that can help treat pneumonia symptoms and support seriously ill patients, but that’s not the same thing as a cure for this virus.) Azar said the HHS branch responsible for emergency preparedness and response is assessing whether the Strategic National Stockpile, the largest national repository of emergency treatments, has adequate medical supplies.

In the meantime, authorities are using basic public health measures: expanding checks to travelers coming from China to 20 U.S. airports, monitoring the people who have become sick and tracing their contacts.

Can the Wuhan virus be spread from one person to another — and if so, how contagious is it? And what’s the incubation period?

China has reported some human-to-human transmission, although that has not yet been seen in the U.S. Scientists don’t really know how contagious it is yet. Azar noted one research paper estimated an infected patient can pass on the virus to anywhere between 1.5 to 3.5 people. Measles, for instances, is much more contagious, with one person spreading that disease to up to 18 other people.

Other coronaviruses have an incubation periods that can range from two to 14 days, but it’s too soon to know if the Wuhan virus has a longer or shorter range.

Can people spread the virus if they have been exposed but show no symptoms?

China has said there “may be evidence” of asymptomatic transmission but U.S. scientists want to get a better look at that data. That’s one big reason Redfield said the U.S. wants to get CDC experts on the ground in China.

“We’re watching closely,” for such transmission, Messonnier said. Fauci also emphasized that even if there is some transmission among people not experiencing symptoms, everything scientists know about coronaviruses strongly suggests that it would not be what propels an epidemic.

“The driver of outbreaks is always a symptomatic person,” Fauci said “An epidemic is not driven by asymptomatic carriers.”

How lethal is it?

Another unanswered question. China has reported 4,500 cases and slightly more than 100 deaths. That’s a high mortality rate, but we don’t know if the reported cases are an accurate representation of the outbreak. It’s possible there are many more people with far milder cases — so mild that they haven’t even gone to seek treatment. In that case, the fatality rate would be much lower.

Azar said our perception of the virus can be skewed by these earliest cases, since we’re looking at the sickest subset of people who have been exposed. “One challenge is that, with an emerging virus like this, our current assessments are based on an uncertain denominator,” he said.

Early reports also indicate that patients who are most at risk of severe disease or death are older or have other health conditions.