[Analytics] How lethal is the Wuhan virus?

Pathologists, microbiologists and public health experts from the University of Hong Kong have expressed different views about the lethality of the Wuhan coronavirus in a bid to help governments shape their strategies against the epidemic. Jeff Pao specially for the Asia Times.

Based on different scientific evidence and viewpoints, some said the mortality or fatality rate, which indicates the lethality of the Wuhan coronavirus could be as low as 0.6% and that it may go down further if more minor cases are recorded.

Others said even if the mortality rate was between 1-2%, compared with 7% of the severe acute respiratory syndrome (SARS), the Wuhan virus could kill tens of thousands of people due to it being highly contagious.

The fatality rate of the Wuhan disease in mainland China was between 2.2% and 2.4% but the percentage outside mainland China was 0.6%, given that only two people had died from 321 confirmed cases, John Nicholls, a Clinical Professor in Pathology at the University of Hong Kong, told Asia Times in an email.

“Whether this difference reflects a delay in disease progression, different criteria in reporting or other treatment factors requires further investigation, but whichever figure you choose, there is certainly a reduced mortality compared with Sars or Middle East Respiratory Syndrome (Mers),” Nicholls said.

In an unpublished transcript from a February 6 conference call with personnel at Hong Kong’s CLSA investment group, which has been widely circulated on the internet, Prof Nicholls is quoted as saying that “a correct comparison is not SARS or Mers but a severe cold. Basically this is a severe form of the cold.”

According to China’s National Health Commission, the number of people infected with the Wuhan coronavirus amounted to 31,774 as of Friday, with the death toll at 722. The fatality rate, or the ratio of the number of deaths to infections, is 2.27%. The figure has remained at around 2.2% since late January.

As of Wednesday, the number of infections in Hubei province totalled 19,665, 70% of the total number on the mainland. The death toll in the central China province amounted to 549 – about 97.5% of all deaths reported in the country to date. The fatality rate in the province was 2.79%.

However, a breakdown of the figures in cities in Hubei paints a different picture. In Wuhan, the center of the outbreak with a population of 11 million, the fatality rate was 4.09% with 10,117 people infected and 414 deaths. In Huanggang, the second-largest city in Hubei, with a population of 6.29 million, the fatality rate was 1.6% with 29 people out of 1,807 infected patients having died.

In Tianmen, with a population of 1.73 million, the percentage reached 7.25% as 10 people out of 138 patients died. In Ezhou, with a population of 1.08 million, the percentage was 4.26% as 18 out of 423 people who had the disease died.

It would be useful to track whether there was a significant difference in mortality and morbidity within the major outbreak cities in mainland China, Nicholls said, as that may give an indication on how severe the Wuhan disease is.

It was important not to look at the mortality rate in Wuhan solely but also the figures outside Wuhan, as Hubei province was overwhelmed by a lot of milder cases because people were not admitted to hospital, Nicholls is quoted as saying in the transcript above. “It’s important not [only] to look at the mortality rate in Wuhan but to look at the mortality rate in Shanghai or Shenzhen” where it was much less deadly, he said.

Meanwhile, some other scientists warned that it could be too early to conclude the fatality rate because “it takes time to die from the coronavirus.”

Epidemic in Hong Kong

As of 8pm on Friday, the number of infections in Hong Kong was 26. One person died from the disease on February 4. The fatality rate was 3.8% but based on very small numbers.

On January 24, Yuen Kwok-yung, chair of Infectious Diseases at the University of Hong Kong’s Department of Microbiology, and his team wrote in an article published in The Lancet, one of the world’s leading medical journals, that the Wuhan coronavirus could be more infectious than SARS as its attack rate was 83%, based on the fact that six out of seven people in a Shenzhen family were infected.

The attack rate for SARS virus ranged from 10.3% to 60%, according to a previous research study.

On February 1, Yuen said in a radio program that if the Hong Kong government did not take any measures, the number of people infected with the Wuhan disease could reach 1.4 million people – about 20% of the city’s population.

He said 14,000 people could be killed by the virus in Hong Kong if an estimated fatality rate of 1%, instead of the current 2%, was used for calculation.

In an article published by Stand News on Friday, a Hong Kong-based columnist explained how Yuen made the estimation.

Yuen cited data from Hong Kong’s Centre for Health Protection that about 17.6 to 25.4% of patients with flu symptoms were diagnosed with seasonal influenza in emergency rooms at peak flu season, it said. He also used the reported fatality rate of 2% on the mainland – but halved it to reduce public panic.

The article said 2,618 out of 1.4 million people would die if the mortality rate of flu-related diseases (0.187%) between 2009 and 2016 in Hong Kong was used instead. And 14 people would die if the global mortality rate of the 2009 H1N1 or swine influenza (0.001 to 0.007%) was used.

In fact, 356 deaths were recorded in Hong Kong during the influenza season between December 30, 2018 and April 6, 2019, according to the Centre for Health Protection.

Sunlight, temperature and humidity

Apart from the fatality rate, the thermal tolerance – the temperature range at which the Wuhan virus can survive – was also another hot debate topic among scientists.

There were articles published on temperature and humidity linked to coronaviruses and SARS, from an outbreak of the latter disease in 2003, Nicholls told Asia Times.

He told CNN on Thursday that the Wuhan virus would be like SARS – as “the world is going to get basically a very bad cold for about five months.”

He also said elsewhere that the coronavirus could survive on a stainless steel surface for 36 hours, but sunlight could shorten its half-life from 13-20 minutes in the dark to just to 2.5 minutes.

The virus could remain intact at 4-10° Celsius for a longer period of time, he said, so Australia and the southern hemisphere would not see any great infections, as they are now in the middle of summer. And, the virus did not like high humidity.

But, Keiji Fukuda, director and Clinical Professor at the University of Hong Kong’s Division of Community Medicine and Public Health Practice, said in an interview with Sing Tao Daily on Friday the Wuhan disease may not necessarily disappear in summer.

Fukuda, a former special representative for antimicrobial resistance for the Director-General of the World Health Organization, said it was too early to predict that the Wuhan virus would be contained in April and May, as it has proved contagious in tropical places such as Singapore and Bangkok.

The value of that observation is at least questionable as most cases of infection in Thailand and Singapore were brought in by Chinese travellers, with no evidence of significant community transmission initially.