How dangerous is new coronavirus and other questions answered
Scientists around the world are racing to understand the deadly coronavirus that emerged in China last month. Several thousand people have already been infected, with the number of cases rising rapidly because of the huge number of Chinese on the move for the lunar new year holiday. International travellers have helped to spread it further afield, including to the US and Europe. There are fears that, if the respiratory illness that probably started in a food market in the central city of Wuhan continues to spread, it will develop into a serious epidemic.
How dangerous is the new coronavirus?
The nCoV coronavirus has killed 170 people in China and infected 7,711. Around 100 cases have been confirmed outside China. Worryingly, it seems to transmit more readily between humans than Sars, a similar coronavirus that killed almost 800 people after it originated in China 17 years ago.
Computer modelling at Imperial College London and Lancaster University in the UK suggest that each new coronavirus case is infecting on average about 2.5 other people.
The new virus is, however, less virulent than Sars, which killed 10 per cent of those infected. So far nCoV has caused severe respiratory disease in about a quarter of the confirmed cases and killed 2-3 per cent of patients.
But experts warn that fatality rates are hard to estimate in the early stages of an outbreak — and the virus may mutate as it passes between people. It is also impossible to predict whether genetic changes will make it more or less virulent.
For comparison, seasonal flu has a mortality rate well below 0.1 per cent but it infects so many people that around 400,000 deaths a year worldwide are attributable to flu. New pandemic flu strains are far more dangerous: Spanish flu in 1918-19 infected 500m and killed 50m worldwide.
How does the virus spread and what is the incubation period?
There is still a wide range of estimates for the incubation period, from two to 10 days according to the World Health Organization. The transmission routes between people are still under investigation. An important question still to be resolved is whether people who are infected can pass on the virus if they are not showing symptoms.
The new nCoV virus is spreading faster than Sars, which affected 8,000 people over eight months. The number of confirmed cases in China the current outbreak has risen to more than 7,700 within a month. Epidemiologists fear that nCoV has already infected tens of thousands more people.
Can masks help protect against infection?
Carrie Lam, Hong Kong’s leader, and other officials from the territory wore protective masks when addressing the media at a press conference on Tuesday. Yet there is considerable debate among public health experts about the preventive effectiveness of covering the face to prevent infection.
Surgical grade masks will help but there is no consensus about whether flimsy mass-produced versions are of any use. The WHO does not mention masks in its advice to avoid infection.
“Wearing face masks may give a false sense of security,” said Bill Keevil, professor of environmental healthcare at Southampton university, adding that good hand hygiene was most important. Tests in his laboratory have shown that coronavirus can survive for four days on common materials such as plastics, glass and stainless steel.
How can doctors tell whether a patient has coronavirus and are vaccines being developed?
Since Chinese scientists published the genetic sequence of nCoV on January 10, laboratories anywhere in the world have been able to test patient samples for its presence. This is done using a procedure called real time polymerase chain reaction (RT-PCR) to identify the virus’s genetic code. But RT-PCR is slow and requires specialist equipment, so researchers are rushing to develop faster, cheaper and more portable tests.
No existing drugs are designed to treat coronaviruses, though some antiviral medicines may alleviate the symptoms. Chinese doctors are giving patients combinations of HIV drugs, and another antiviral developed to treat Ebola has shown promise against coronavirus in animal tests. Clinical experience in China will show whether any of these help against nCoV.
A crash programme to develop a vaccine to prevent nCoV infection is also under way under the auspices of the Oslo-based Coalition for Epidemic Preparedness Innovations (Cepi) — a $750m partnership set up in 2017 by governments, industry and charities to prevent future pandemics.
Cepi has launched three projects using different technologies to prepare nCoV vaccine candidates. Richard Hatchett, chief executive, said the aim was to have one ready for preliminary testing on human volunteers within 16 weeks. But even if the programme goes well, no vaccine is likely to be ready for mass administration in less than a year.
Is the WHO right not to have declared an international emergency?
At a two-day meeting last week, the WHO emergency committee voted by a very narrow margin not to declare a so-called public health emergency of international concern. Such a measure has been announced five times over the past decade, including over last year’s Ebola outbreak in the Democratic Republic of Congo.
The WHO justified its decision to hold fire on the grounds that the disease had not spread beyond China sufficiently to justify a global emergency. Yet many international health experts have called that decision a mistake, saying that they expect the WHO to change its mind very soon if the outbreak continues to spread at its current rate.
Peter Piot, director of the London School of Hygiene and Tropical Medicine, said: “The fact that there are cases now in so many countries and that it is spreading fast is of international concern. I do not know what more they need.”
Declaring a public health emergency would not make a huge difference in practice, given the scale of international action already taking place, but it would be an important symbolic statement. The WHO said it was “on standby to reconvene the emergency committee at very short notice”.
Additional reporting by Primrose Riordan in Sydney