While research into COVID-19 has progressed at an impressive speed, according to experts, gaps remain in the world's knowledge about the virus, including information about how it spreads.
After identifying the new coronavirus in humans for the first time, Chinese officials reported 44 cases to the World Health Organization (WHO) on December 31. In the two months since that report, cases have increased to more than 82,000, including 2,804 deaths and spread to nearly 50 countries.
To evaluate measures to curb the spread of the virus and to learn about it, WHO and China assembled a group of 25 Chinese and foreign experts to investigate the epidemic in the origin country. On February 24, leaders of the WHO-China Joint Mission held a press briefing to share the findings of their investigation, which began on February 16.
They identified what they believe to be the suspected fatality rate, case demographics and recovery times for mild and severe cases.
"I think it's about as much as we can expect," Vincent Racaniello, a professor of microbiology and immunology at Columbia University told Newsweek. "I think we've made remarkable progress in just a few months."
Left unanswered are questions about hosts for the virus, ways it can be transmitted and the risk asymptomatic patients present.
How the virus is transmitted...
The general consensus is that the virus is transmitted through respiratory droplets and contact with contaminated surfaces. That may not be the only way to contract the virus, though.
The new coronavirus has been detected in stools of some patients, suggesting that it could be transmitted by the fecal-oral route, according to Dr. Liang Wannian, head of Expert Panel of COVID-19 Response of China National Health Commission.
One way fecal-oral transmission occurs is when a person consumes food or water that has been contaminated, according to the Centers for Disease Control and Prevention. Another way is by someone touching a contaminated item and then their mouth without washing their hands adequately.
Peter Rabinowitz, director of the University of Washington's Center of One Health research, told Newsweek it's difficult to determine if someone contracted the virus from someone who didn't wash their hands properly after using the restroom, a common method of fecal-oral transmission, or if they were just in a close proximity to an infected person and exposed to droplets.
A third way that researchers suspect the virus could be transmitted is by inhaling infectious particles, a method known as aerosol transmission.
Liang noted that the epidemiological significance and value of the additional transmission possibilities must be further confirmed.
If people who don't know they have the virus can spread it…
Cases involving asymptomatic patients, people who aren't exhibiting symptoms, have been identified, according to Liang. However, researchers still don't know whether those cases were people with asymptomatic infections or carriers whose virus was in the incubation period, the time before the onset of symptoms. It's unclear if asymptomatic carriers can spread the disease.
"If asymptomatic and pre-symptomatic transmission is common, then the models get tipped towards some of our more frightening projections," Nathan Grubaugh, an assistant professor at the Yale School of Public Health, told Newsweek. "Unrecognized outbreaks could go on for weeks, spreading the virus to new locations, before prevention and control measures could be put into place."
In determining asymptomatic transmission, Nicole Errett, a disaster researcher at the University of Washington, told Newsweek it was a bit like "finding a needle in a haystack." Officials aren't aware a person is transmitting a virus until someone gets sick and by the time that happens, the person has interacted with so many people that it's difficult to trace.
How long the virus survives on surfaces…
Another important piece of the puzzle, according to Errett, is knowing how long the virus lives on different surfaces. This will reveal if people can become infected with the virus by touching an object that someone with the virus touched. She also advocated for identifying what, if any, differences there are in how the virus lives on different materials such as paper versus stainless steel.
At this point, it's unclear how long the virus can survive on a given surface. WHO acknowledged the virus' survival could be a matter of hours or even days and vary depending on the conditions.
Which animals are hosts…
Currently available data in China suggested that bats may be the new coronavirus' host, but Liang noted that's not definitive. It's also possible, according to Liang, that pangolin, also called a scaly anteater, could be a host.
"I think it is [important to know hosts] because we need to know where the next one is coming from," Racaniello said. "We knew that bats were a source of coronaviruses for a while but there wasn't a lot of surveillance of other animals. The pangolin was a real surprise."
