Coronavirus vs flu: how do they compare?

The world is in the grip of a new coronavirus outbreak – which has reached almost every continent except Antarctica.

As of March 2, a total of 88,913 cases of COVID-19 have been reported to the World Health Organization (WHO) - and 90% of those are in China, mostly in one province.

In China, a total of 2,912 people have died, whereas outside China, there have been 127 deaths, among 8,739 cases in 61 countries.

More than 130 countries haven't detected a case yet.

The Director-General of the WHO, Tedros Adhanom Ghebreyesus, declared the spread of the virus a global health emergency on January 30.

“Our greatest concern is the potential of the virus to spread to countries with weaker health systems, and which are ill-prepared to deal with it.”

At the same time in the northern hemisphere, it’s the tail-end of flu season. So far in the US, there have been around 32 million flu illnesses and 18,000 deaths from flu, according to the Centers for Disease Control and Prevention.

So how does coronavirus compare to the flu?

Deadliness

The severity of an illness can be measured by its case-fatality or death-to-case ratio.

In percentage terms, around 0.06% of those who’ve had flu this season in the United States (based on the figures above) have died from it.

Worldwide, annual flu epidemics are estimated to result in about 3 to 5 million cases of severe illness, according to the WHO, and about 290,000 to 650,000 respiratory deaths.

Based on the figures so far around the new coronavirus outbreak, which causes fever and a cough, ranges from 1.4% outside China - to 3.4% if you include the China figures.

Medical journal The Lancet warns any estimates should be “treated with great caution because not all patients have concluded their illness (ie, recovered or died) and the true number of infections and full disease spectrum are unknown”.

It adds: “Importantly, in emerging viral infection outbreaks the case-fatality ratio is often overestimated in the early stages because case detection is highly biased towards the more severe cases.”

Severe Acute Respiratory Syndrome or SARS – first identified in China in 2003 and also caused by a coronavirus – had a case-fatality ratio of 10%.

The 1918 influenza pandemic (Spanish flu) had a case-fatality ratio of less than 5%, according to The Lancet, which notes: “It had an enormous impact due to widespread transmission, so there is no room for complacency.”

Contagiousness

How far a virus will spread comes down to what’s known as the reproduction number, or R0. It relates to how many people each infected person will pass the illness on to.

There have been various estimates for new coronavirus so far from different sources, but the WHO put a preliminary estimate as between 1.4 and 2.5.

The pandemic (H1N1) 2009 influenza virus, which was also known as swine flu, had a R0 of between 1.2 to 1.6, according to the WHO, which made controlling its spread easier than viruses with higher transmissibility.

Measles has a much higher R0 at 12 to 18 people.

Vaccine

Although flu kills a small proportion of those infected with it, it infects millions of people – which is why vaccination is recommended.

With coronavirus, there currently is no vaccine – but one is being worked on.

At the World Economic Forum’s Annual Meeting in Davos, the Coalition for Epidemic Preparedness Innovations (CEPI) held a press conference to announce just that.

Protection

Like the common cold and flu, coronavirus is spread between people in droplets when they sneeze or cough. The World Health Organization recommends taking the following precautions:

1. Frequently clean hands by using alcohol-based hand rub or soap and water

2. When coughing and sneezing cover mouth and nose with flexed elbow or tissue – throw tissue away immediately and wash hands

3. Avoid close contact with anyone who has fever and cough

4. If you have fever, cough and difficulty breathing seek medical care early and share previous travel history with your healthcare provider

5. When visiting live markets in areas currently experiencing cases of novel coronavirus, avoid direct unprotected contact with live animals and surfaces in contact with animals

6. The consumption of raw or undercooked animal products should be avoided. Raw meat, milk or animal organs should be handled with care, to avoid cross-contamination with uncooked foods, as per good food safety practices.