SINGAPORE - The Ministry of Health (MOH) announced on Wednesday (Jan 22) that it is setting up a multi-ministry task force to tackle the mysterious Wuhan virus that has already infected more than 400 people in China.

Although it has yet to reach Singapore's shores, increased air travel in the lead-up to the Chinese New Year holidays has led to the ministry - as well as other agencies across the world - stepping up precautionary measures to either prevent entry of the disease or contain its spread.

As of Wednesday afternoon, the Wuhan virus, a type of coronavirus which causes pneumonia in its victims, has claimed nine lives.

But what is the virus and how did the Wuhan virus spread to people?

Here are some questions and answers about the Wuhan coronavirus behind the latest outbreak.

1. What is a virus?

Viruses are microscopic parasites that lack the ability to survive and reproduce outside living organisms, which includes animal, humans and even bacteria.

For this reason, it is debatable if they are truly "alive". They become active only when they come into contact with living cells, which they then try to hijack to produce more viruses.

Even so, viruses are made of biological material and have the biggest population of any biological entity on earth, triggering responses in living things that range from unnoticeable reactions to death.

Some experts believe that nearly 10 per cent of the current human genome is viral genetic material, as a result of viruses infecting human cells for millennia.

2. What are coronaviruses?

They belong to a large group of viruses that usually infect only animals, and are so named for the crown-like spikes on their surface.

But from the mid-1960s, scientists began identifying coronaviruses that affect humans, with seven types of these viruses classified to date, according to the United States Centres for Disease Control and Prevention.

Four of these typically cause mild to moderate upper-respiratory tract illnesses like the common cold, with well-known symptoms such as sore throats, cough, and headaches.

But the remaining three have more recently caused severe repercussions on human health as scientists scrambled to understand them.

The first is the infectious severe acute respiratory syndrome (Sars) coronavirus, which killed almost 800 people in 32 countries 17 years ago.

The other two are the Middle East respiratory syndrome coronavirus (Mers-CoV), which was first reported in Saudi Arabia in 2012 and later spread further, and the latest Wuhan virus (2019-nCov) which killed its first victims in the Chinese city of Wuhan.

3. How could the Wuhan virus spread from animals to humans?

Scientists have speculated that the virus from the latest Wuhan outbreak, like the Mers and Sars viruses that preceded it, evolved from coronavirus strains that previously affected only animals.

This ability of a virus to "jump" from animals to humans is not unusual and has given rise to a category of illnesses called zoonotic diseases, which also counts among its ranks diseases caused by non-coronavirus viruses like the human immunodeficiency virus (HIV) and Ebola.

Zoonotic viruses generally have a single strand of genetic material called RNA, which is more easily copied or mutated than humans' double-stranded DNA, which accounts for their virality.

To date, the Wuhan coronavirus has been closely linked to Huanan seafood market in Wuhan, which reportedly also peddled live animals like deer and animal parts in addition to seafood.

Scientists have said such "unnatural situations", where animals are brought together and often housed in bad conditions in close proximity to people, create opportunities for viruses to hop between animals. The virus could then have changed so that it is able to infect humans and eventually start spreading between people.

Every virus typically infects a certain type of living host organism, said Dr Sebastian Maurer-Stroh, deputy executive director of research at the Agency for Science, Technology and Research's (A*Star) Bioinformatics Institute.

"Viruses can shift their host preference through mutations... Some viruses mutate much faster," he added.

4. How might the Wuhan virus spread between people?

The Wuhan coronavirus is understood to spread much like the common flu does - through the air when an infected person coughs, through close contact such as shaking hands with an infected person, or touching an object with the virus on it before touching one's mouth and eyes.

For now, virologists have said that the Wuhan coronavirus - based on reported rates of infection - is likely not as infectious as the Sars virus. But there are concerns that the Wuhan virus' current reported 2 per cent death rate - two out of 100 infected people die - is not representative and that the virus could further mutate to become more lethal.

Dr Michael Wong, a senior family physician at Raffles Medical, said the virulence of the Wuhan virus cannot be underestimated. "With mutations, the virus could increase in virulence and transmissibility, leading to a serious pandemic," he said.

The Chinese government has classified the Wuhan virus outbreak in the same category as the Sars epidemic, meaning compulsory isolation for those diagnosed with the illness and the potential to implement quarantine measures on travel, said Dr Wong.

There are also worries that the number of infections is yet under-reported, with many brushing off symptoms as those of the common flu.

5. How is the Wuhan virus different from the Sars virus?

It is a different strain and, for now, has reported a lower fatality rate than the Sars virus.

The World Health Organisation estimates that the overall fatality rate for Sars patients to be between 14 per cent and 15 per cent, while that for Wuhan is currently at 2 per cent.

Researchers have said that the Wuhan virus shares only 76 per cent of its genetic material with the Sars virus - a big difference in genetic terms much like "comparing a dog and a cat".

There is, however, speculation that both viruses originated from bats. Recent reports have also suggested that the Wuhan virus might be linked to snakes too.

6. Should I panic?

No, said professor Paul Tambyah, from the department of medicine at NUS Yong Loo Lin School of Medicine.

"I don't think we should panic as panic is never a good approach."

Instead, we should be concerned.

He said there are measures in place to control the outbreak here and elsewhere. The public should be concerned and thus be vigilant about maintaining good hand hygiene, seeking medical attention if unwell and staying home, he said.

7. Should I wear a mask?

Wear a surgical mask when you have a cold or flu, to prevent the transmission of airborne germs.

Some doctors have been wearing surgical masks as a precautionary measure at work, so some people may wonder if they should dig out their N95 masks too.

But there is no need to, said professor Leo Yee Sin, the executive director of the National Centre for Infectious Diseases. Instead, they should wear surgical masks.

"N95 masks are of a very special design. They are very difficult to breathe in. If you find the N95 mask easy to breathe in and comfortable, you are wearing it wrong and it's no use," she said. "It's only when it is difficult to breathe that you are wearing it correctly."

It is thus not recommended for the general public, she said.

In fact, if you use it wrongly, it may make things worse because you think you are protected when you are not, she said.

Dr Leong Hoe Nam, an infectious disease specialist at Mount Elizabeth Novena Hospital said that everyone with respiratory symptoms must wear masks, now that there's human to human transmission.

8. Can I still visit China?

The MOH on Thursday said Singaporeans should avoid travelling to Wuhan, stepping up a notch from its advice on Wednesday for people to defer non-essential travel there.

The ministry said it updated the travel advisory "in view of the developing novel coronavirus situation in Wuhan and other parts of China", with confirmed cases spreading beyond Wuhan to Beijing, Shanghai, Tianjin and Guangdong, which abuts densely populated Hong Kong.

It also cited the travel halt imposed by the Chinese authorities on Thursday, as all flights out of the city were cancelled and trains, buses and ferries suspended.

The MOH reminded the public to continue to exercise caution and pay attention to personal hygiene when travelling to the rest of China.

All travellers should monitor their health closely for two weeks upon returning to Singapore and seek medical attention promptly if they feel unwell, and also inform their doctor of their travel history, said the ministry.

If they have a fever or respiratory symptoms like a cough or runny nose, they should wear a mask and call the clinic ahead of the visit.

9. Should I be worried about China tourists coming into Singapore?

Singapore is stepping up precautionary measures, in anticipation of more travellers in the lead-up to the Chinese New Year holidays.

The expanded measures include temperature screening for all travellers arriving from China - not just Wuhan alone - at Changi Airport from Wednesday and issuing health advisory notices to them.

"However, people who are in the incubation period - likely seven to 14 days based on known characteristics of other corona viruses - might not have started showing symptoms such as a fever, and, hence, not be detected by the thermal scanners," said Raffles Medical's Dr Wong.

"With increased awareness of the infection, it is hoped that those who experience symptoms would isolate themselves and see a doctor as soon as possible so as to prevent spreading the infection."

10. Is there a cure for the Wuhan virus infection?

There is no specific treatment to cure illnesses caused by human coronaviruses, including pneumonia caused by the Wuhan virus.

Patients typically recover on their own after some time by depending on their immune system to fight the infection.

Treatment mostly involves tackling flu-like symptoms from infections and making patients more comfortable, such as providing them with breathing apparatus to help with breathing difficulties.

In some cases, antiviral drugs are available to shorten the duration or reduce the severity of the illness by decreasing the ability of the coronavirus to reproduce, effectively isolating it.

A*Star's Dr Maurer-Stroh said that "as a rule of thumb, a virus that spreads widely is often less severe".

11. Should I get a flu jab?

A flu vaccine will not help protect you against the Wuhan coronavirus. There is no vaccine to protect against coronaviruses. The influenza virus, that a flu jab protects against, is not a coronavirus.

However, according to an advisory from Raffles Medical, you should still get a flu jab if you are travelling to exposed areas to prevent you from contracting influenza symptoms and signs that may mislead screening authorities at temperature checkpoints.