For the novel coronavirus, no one knows where it came from, or how long it will stay.
Even China, one of the few countries in the world that has almost contained the epidemic, is still far from claiming victory.
One of the main challenges has been a lack of information, even for China with its experience of dealing with SARS, a coronavirus with genetic similarities to the new one.
During the 47 days between mid-January and the beginning of March, China published seven national diagnostic and treatment plans.
Reviewing those plans shows how cunning this virus is and how unprepared the world was.
SARS, which hit China about 18 years ago, was believed to be non-infectious during its incubation period. But the novel coronavirus, a close family member of SARS, has proven to be more powerful.
In the fourth edition of the diagnostic and treatment plan that came out at the end of January, experts said that the new type of coronavirus has an incubation period that could be longer than that of SARS.
The virus also confused medics in terms of its clinical symptoms.
Starting with symptoms resembling the flu and pneumonia, authorities soon updated these to include issues concerning the upper respiratory tract. Further, they also found it could target the metabolic and digestive systems.
As the list of symptoms got longer, the fifth edition – in early February – revealed another dark reality: Some infected people did not have any symptoms at all.
During an interview with CGTN, Yuan Zhiming, director of the Wuhan National Biosafety Laboratory, said the virus is "quite different" from other coronaviruses in many ways. "Some patients show mild symptoms. Some test positive for the virus but do not show any symptoms. Some patients' condition deteriorated more quickly than others. Different research institutions get to different conclusions on the survival time of the novel coronavirus."
In addition, the number of vulnerable groups continued to expand. The elderly had been the first group thought to be more at risk than others. The fourth edition added children and infants. However, the fifth edition said "the whole population is generally vulnerable."
Now we know that the virus can be transmitted in multiple ways, including airborne droplets, feces, and what has been called "aerosol transmission." But that information came at the cost of losing many patients.
What's worse is that there is not a specific cure to a brand new disease. Some have proposed re-purposed medicine such as lopinavir and ritonavir which are used to treat AIDS, or chloroquine that's used to cure malaria.
That list is also getting longer, but uncertainty stops many from trying such cures.
As Yuan said, although we have learned a lot in the fight against COVID-19, our knowledge is still very limited. We need to invest more time to find the answers to some basic questions in order to learn more about the pandemic.
From the very beginning, China tried to contain the outbreak by adopting strict social distancing measures, and that seems to be the only thing that's certain amid so many uncertainties.