How deadly is the new corona virus?
- It is difficult to calculate exactly how many of those infected by the new corona virus die. Dividing the number of deaths only by the number of infected does not give a fair picture, says Sergio Brusin, expert at the European Disease Protection Agency ECDC's crisis and command center.
At present, WHO indicates a mortality rate of 3.4 percent. Previous assessments have been between 1 and 2 percent. ECDC says around 2 percent - but the calculations at the present time are likely to overestimate mortality.
- Many who have received a mild variant of the disease are not yet included in the statistics. The more mild cases detected and recorded are likely to cause mortality to decline, but much more data is needed before we know for sure, says Sergio Brusin.
Why does mortality differ between countries?
- The fact that death rates can differ widely between different countries is because testing looks different. Some countries, such as South Korea, not only test the most severely ill cases but have also tested wider stocks in the population and therefore found more people with a mild variant of the disease. Therefore, their mortality has also gone down, says Sergio Brusin at ECDC.
It is also the development in South Korea that ECDC is mainly looking at to calculate what a major outbreak could look like in Europe. Right now, ECDC estimates that the virus may have a mortality rate of between 0.5 and 1 percent.
Is it reasonable to compare the new corona virus with regular seasonal flu?
- There are similarities - like how it infects. But the disease itself is clearly more serious, with a higher number of deaths. And the effect on health care seems to be much higher compared to the seasonal flu.
How contagious is the new virus?
- An infected person is estimated to be infected between two and three people, which is comparable to how common influenza infections are, says Sergio Brusin.
- We don't know exactly how the virus behaves but on different types of surfaces and if and if so how long it is contagious there. We also do not know how really small drops can affect the contagiousness. There seem to be traces of the virus in feces and we also don't know how it affects the spread, he says.
Can infectivity decrease over time?
- It's hard to say at the moment. The only way seems to be to introduce very powerful social control mechanisms, as China did.
- They stopped trains, buses and people from moving freely. Nothing like that has been done in the history of modern infectious medicine, he says.
How many get so sick that they need hospital care?
- Between 15 and 20 percent. The number has decreased as it seems possible to care for people with less severe symptoms at home, with the help of health care professionals. It is only if you need intensive care that hospitalization is required. About five percent of those infected become so seriously ill that they require intensive care.
Sergio Brusin estimates that number will not decrease - unless the virus mutates and causes a milder disease.
Are there any signs that the virus can mutate and become milder or more dangerous?
- New diseases tend to become more mild over time, but at present we do not see it in terms of the new corona virus.
- We cannot rule out that the virus will mutate into a milder variant, but it cannot be ruled out that it can also mutate and become more dangerous. It is more likely to be milder than more dangerous, but at present we cannot rule out anything.
- We have seen in the past that some forms of Ebola virus have mutated and become more dangerous, but this is not common. For it is not so effective for a virus to kill its host, because then that host cannot spread the virus further.
Can you get infected without having symptoms?
- Right now, we think it's pretty unlikely. It is difficult to know what is meant by not having symptoms. If you have a very mild variant of the disease such as a little cough or fatigue you can still be infected. We have not yet seen any studies that show that people who have no symptoms are still infected. Of course, we cannot rule it out, but it often does not happen with viral diseases. However, some types of symptoms usually exist. Like light coughing or tiredness, a bit like the beginning of a common cold.
Does the child spread the disease?
- Children do not appear to be the group that spreads the infection. We see cases where children get sick, but the evidence that the child would spread the disease is very shaky at the moment.
Should countries close their schools to prevent the spread of infection?
- It is an understandable thing to do, as it is a relatively simple measure to introduce. If it has a big effect - probably not. But if we look at older children, they may contribute a bit to the spread of infection on the way to school. But it is not an extremely effective measure, but I allow the authorities to be attracted to it because it is a simple measure.
Does climate play a role in the spread of virus?
- It's hard to say at the moment. The MERS corona virus, which spread in the Middle East, was well adapted to the warm climate there. Other types of coronavirus thrive best in cold, dry climates. We see that countries with colder winter weather have more cases of the new corona virus at the moment, but also warmer places like Hong Kong and Singapore are affected, as well as Malaysia which has a tropical climate.