The “Perfect” Communicable Disease Outbreak

Make no mistake, the 2019-nCOV virus is not a remake of SARS. It is a blockbuster sequel. Like Empire Strikes Back. And like all well-made sequels, there should be many surprising twists and turns to the plot. I call this a sequel because both SARS and 2019-nCOV belong to the coronavirus family of viruses.

For other old coots like me, we have fought and survived SARS. I wouldn’t call it a victory, but we survived. That’s enough for me because I know people who literally and physically did not survive SARS. The 2019-nCOV is the big test for the current young generation of healthcare workers.

Like most major and surprising developments, there is good news and then there is bad news.

First the good news. From a case-fatality (CF) rate perspective, the 2019-nCOV is less lethal than SARS. The CF rate for SARS was about 10% (10% of those infected died) while the CF rate for 2019-nCOV is hovering around 3%. The other good news is that the international healthcare community has developed very quickly diagnostic tests that can give you a result in about 24 hours, versus SARS when diagnostic tests took about 2 to 3 days to give a result and these tests were only developed late into the outbreak. But even so, we should remain guarded on this point because we are not sure when the tests can pick up the disease because we do not know for sure when the disease turns detectable. The third piece of good news is that this new disease is spread by droplets (and not airborne) like SARS and a good mask and universal precautions should be enough to break the transmission.

So much for the good news. Now for the bad news, of which there are many.

The 2019-nCOV outbreak (I wish someone in WHO or China will give this bug a more catchy name, like R2D2 or BB8 for example) is designed to perfection in several ways. First, it is perfect in timing. It blew up about a week before Chinese New Year in China, the busiest week of the year when hundreds of millions of Chinese are travelling back to their villages or for holidays, both within China or beyond China’s borders. The size of the travelling population in the week preceding Chinese New Year has been likened to the entire populations of France, Britain, Germany, Italy and Spain going on the road at the same time. Or the whole of USA moving. In other words, timing-wise, it is timed to perfection for maximum dissemination/propagation of the virus. And it is not done yet. These people now in their hometowns have to return back to their workplace – so a few hundred million people have to go on the road again soon in the next one or two weeks.

In comparison, SARS occurred post-Chinese New Year in 2003, in mid-spring, when Chinese New Year travelling had already been done and dusted.

Outbreak-wise, the 2019-nCOV is location-perfect. It has chosen Wuhan, the city right in the middle of the world’s most populous country with the most comprehensive network of high-speed trains, otherwise known as the High-Speed Rail (HSR). Wuhan is a bit like the Toa Payoh of Singapore in terms of location- smack in the middle. From Toa Payoh, you can easily travel to Jurong, Yishun, the CBD or Changi by a network of expressways. Similarly, from Wuhan, you can travel to the populous Sichuan province and Chongqing in the west, Beijing in the north, Shanghai in the east or Guangzhou and the Greater Bay area in the south within 4 to 6 hours by HSR.

Wuhan and its surrounding areas are so central that since ancient times, it has been a battlefield for different armies contesting for supremacy of China. This is especially evident in the Three Kingdoms period (at the end of the Han Dynasty in the third century) where the Three Kingdoms of Wei, Wu, and Shu fought around Wuhan and the nearby cities, such as Jingzhou. Wuhan is at the junction or confluent point of these three kingdoms, which underlies the centricity of it’s location. The biggest battle of the Three Kingdom period took place in Chibi or Red Cliff on a tributary of the Yangtze. It’s so famous that director John Woo made a two-part movie about it (Battle of Red Cliff) with a star-studded cast in 2008. Chibi is a stone’s throw from Wuhan and one of the first cities to be locked down together with Wuhan.

You cannot choose a better location than Wuhan in Hubei province to plant a disease outbreak in China. As they say, location, location, location. And Dr Evil couldn’t have chosen a better location even if he wanted to.

Next is the speed of transmission. In the past, a migrant worker may take up to four or five days to return to his kampong from centrally-placed Wuhan – You take a few slow trains, take a bus, hitch a ride and walk etc. Now with the HSR, you are home probably on the same day, within 24 hours, for 90% of China’s migrant working population. China’s HSR and road network is as good as any developed country in the world. That means the spread of 2019-nCOV is several times faster than the 2003 SARS, thanks to great travel infrastructure in 2019. In other words, in terms of coverage, 2019-nCOV beats SARS hands down.

Outside of China, the spread is also of many orders of magnitude faster and bigger than SARS, thanks to the huge number of Chinese travellers going overseas for holidays over the festive period. In 2003, SARS only came to Singapore because the virus travelled to Hong Kong and several Singaporeans caught the infection when they travelled to Hong Kong and stayed at the Metropole Hotel and brought the virus back to Singapore. That took time and quite a few people. Now in 2019, you can see that most countries have the infection introduced to them by people travelling from Wuhan directly to these countries. The number of travellers coming from Wuhan number in the tens of thousands in any given month to major cities in Asia. The number of Chinese travelling abroad in 2003 was a fraction of what we have in 2019. In 2003, we had to “import” SARS from HK, which in turn was imported from Guangdong, China. Now Wuhan has directly “exported” 2019-nCOV to Singapore and several other countries.

SARS lasted quite a few months in 2003. In the end there were about 8000 cases and 800 deaths. Contrast this to 2019-nCOV. Official investigations into this new disease started after the Chinese National Health Commission was alerted to the outbreak on 30 Dec 2019. It took only 4 weeks since then for this new disease to infect about 4000 people, half the total number of SARS patients. It is no surprise that the official (let alone the unofficial) statistics reflect the speed of the spread. This hobbit predicts that many more people will be infected with 2019-nCOV than SARS. Hopefully with a lower CF rate, and better facilities, therapeutic options now than in 2003, not too many people will perish. But I am not betting the farm on this hope…..

These are the hard truths. But there is more. The prospects may be grimmer than the above because of our imperfect understanding of the disease on two fronts:

• We do not know if the infected person is infectious during the incubation period or not
• Simple signs like fever may not be a reliable sign for the disease

These two points dramatically changes the game for us battling this new disease. SARS patients were not infectious during the incubation period and when they were infectious, they had fever. That gave us time and ease of detection. Outbreak fighters were given up to one incubation period (a minimum of ~7 days) to locate close contacts of SARS patients so that they could be quarantined and in doing so, break the chain of transmission. Now, if claims that a patient is infectious even during the incubation period is true, that one-week window of safety may no longer be there. There may be no time to find and round up close contacts. The Chinese believe this is so while local (Singapore) experts think this point is still debatable. We don’t have conclusive evidence on this one way or the other.

The next point is that fever may not be a reliable sign, although according to a study published in The Lancet on 24 Jan 2020 for a cohort of 41 patients, 40 out of 41 or 98% of patients developed a fever, though it was not stated if they developed the fever early or late into the course of the disease. Other reports cite that up to 30% of patients do not develop fever. The jury is still out for fever as a reliable sign. From a study design point of view, the power of a study based on a cohort size of 41 is debatable. We need bigger studies.

In Singapore, there is no evidence of community spread. Strictly speaking, there is no cause for panic. Or even N95 masks. So surgical masks should suffice for front line staff unless you are dealing with a suspect case, pending serological confirmation, in which case you need to get a N95. But if you are dealing with a suspect case, you are probably working in a restructured hospital, armed to the teeth with PPEs (Personal Protective Equipment) and as a SARS veteran yourself or a younger doctor supervised by a SARS veteran, you should be OK.

The problematic issues for now remain on two fronts

• Where do we get surgical masks (and other PPEs) in the private sector?
• How to risk stratify and what responses should we make to different risk levels

For folks in the private sector, surgical masks are getting increasingly if not impossible to get. Strangely, you can still get your box of N95s from SMA. But no one can promise you your supply of surgical masks beyond the odd box of 50 masks here or there. That is hardly reassuring to the GPs in the frontlines. This hobbit would like to think or hope that someone is sitting on a war-chest of surgical masks (and gowns) like Joseph hoarding grain in biblical times, now ready to unlock the supply that will be enough to feed Egypt in a famine lasting seven years. Or at least enough masks for seven weeks lah……

As for risk stratification, policy makers have made it clear that travel to China is a major risk factor.

Returning (from China) students and healthcare/eldercare workers are required to be quarantined. The selection of these groups reflects the thinking that these are people with the potential for spreading the disease to many people quickly, should they be infected.

A much more worrisome point is that it has now been reported that 2000 persons who are now in Singapore have been to Hubei recently. How many of these are already carrying the infection? What are the chances that community or local transmission will arise from these 2000 persons?

The next question we must ask is that how do we enforce a proper quarantine for these groups? Should they be monitored closely like in the past during SARS? Does home quarantine suffice, since fever may not be a reliable sign and they may be infectious during incubation and hence may spread the disease to family members? Should we think about hotel quarantine instead? (Since there are going to be quite a few empty hotel rooms soon, I guess)

There are many questions. But as with any novel disease outbreak, the answers are few. We need to buckle down, keep our morale up, and observe strict discipline in our infection control practices. These are obvious.

What is less obvious, and quite worrisome, is that we must avoid the mistake that many generals make – generals often fail or get defeated when they fight the last war.

These is a new enemy. A new war. We have to think new too.

3 thoughts on “The “Perfect” Communicable Disease Outbreak

  1. Thank you for weighing out the facts and sharing you realistic views. Much informed.
    Praying together for the “return of the J”.

    Like

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