Imagine being seated for eleven hours on a plane next to a passenger wearing an anti-viral face mask, and with a hand sanitizer clipped to his back-pack, which he dipped into for cough relief lozenges. This was my stressful experience last week; and it could be a common anxiety in the months ahead. IATA has estimated a revenue loss of about USD $30 billion this year, most of which would be in the Asia-Pacific region. But this was assuming that Covid-19 would play out like SARS in 2003, which caused a sharp decline for six months, followed by a quick rebound. Many business sectors other than aviation are likewise hoping for recovery after the summer. The fate of the Tokyo Olympics depends on recovery by July.
SARS was a very severe disease. Most patients developed pneumonia, and about 10% died. According to China CDC, about 5% of Covid-19 patients have critical diseases including respiratory failure, septic shock and multiorgan failure. In about 14% of cases, the virus causes severe diseases including pneumonia and shortness of breath. But about 80% of patients have a mild form of disease. Reassuring as this may sound, the mildness of most cases makes Covid-19 a far greater global menace than SARS. Those infected with SARS were not infectious during the incubation period. This greatly facilitated the task of tracking infected contacts of SARS cases; surveillance could focus on those contacts who developed symptoms.
The village of Eyam in Derbyshire, central England, was unlucky to discover that the pandemic, then raging 150 miles (226 kilometers) to the south in London, had arrived on its doorstep.
The pandemic was the plague – the year was 1665. The disease had reached Eyam through the delivery of flea-ridden cloth from London to the local tailor, who would then made clothes for the villagers. The fleas carried the plague bacterium and the recipient of the cloth was the first to die.
Within three months another 41 villagers had perished. By spring 1666 a newly appointed rector proposed that, for the sake of other plague-free towns in the Peak District region, the village should self-isolate. A local Earl offered to guarantee food for the town (supplied on a rock at the edge of the village, paid with coins immersed in vinegar – see location below). In June 1666 the villagers reluctantly agreed. Over the summer the plague returned with a vengeance and there were five or six deaths each day. Eventually one third of the population died. But the nearby towns stayed plague free.
Since 2017, in modeling the threat from wildfire on communities in California, the significant new RMS innovation has been in capturing the process of “spotting” (i.e. identifying new outbreaks of fire far from the fire-front). Strong dry winds bring swarms of glowing embers from a raging wildland fire, which can travel long distances. Should these embers settle on shingle roofs, wooden patios or a leaf-filled plastic gutter, a fire will start. Unchecked, the fire will consume a house.
In high-density housing suburbs, wind-driven fire can spread from building to building and consume a whole neighborhood – as happened in the city of Santa Rosa in 2017. And the only way to stop an outbreak is to intervene: to extinguish each ember-ignited fire before it can spread.
Modeling ember ignitions requires sampling the speed
and direction of the wind and also anticipating what proportion of fire-starts get
extinguished before they can spread. Still it only takes one unchecked fire to
burn down the town.
This same process, in modeling “spotting”, is key to anticipating the spread of the new coronavirus into western Europe and North America.
Epidemiologists are disease detectives. The
investigative insights of a forensic epidemiologist are exemplified by Sherlock
Holmes, whose creator, Arthur Conan Doyle, qualified as a medical doctor in
Edinburgh. With limited information, some of which may be dubious and
misleading, epidemiologists search for hidden clues as to the cause of a
disease and its manner of population spread and use statistical modeling techniques
to estimate the degree of disease contagion and the number of cases of
Prof. Neil Ferguson heads the World Health Organization (WHO) Collaborating Center for Infectious Disease Modeling at Imperial College London. His search for scientific understanding using sparse observational data dates back to his theoretical physics PhD at Oxford. Like others trained in theoretical physics, Prof. Ferguson is not shy in making mathematical forecasts that may be at odds with partial data of suspect reliability. Misreporting blighted the Chinese response to the 2002 SARS outbreak.
When the Middle East Respiratory Syndrome (MERS) was first identified as a coronavirus in 2012, the case fatality rate was very high at 35 percent; but thankfully there was very low human-to-human transmission. Such transmission happened in healthcare settings, or to a much lesser extent in households where people caring for an infected person had close contact.
Camels were identified as a “reservoir host” for MERS, with infection primarily caused through direct contact with camel fluids. As evidence of very low human-to-human transmission, there were no MERS cases reported in either the 2012 or 2013 Hajj pilgrimage to Mecca, although an Indonesian couple may have caught MERS in the 2014 Hajj.
In China, there is an even larger annual migration tied to the lunar calendar – as the lunar New Year starts on Saturday, January 25. This is normally a time of happiness and celebration during family reunions. This year, there will be fear and foreboding over the new coronavirus, which emerged in December from a seafood market in Wuhan, Central China. On January 21, Chinese health authorities confirmed human-to-human transmission of the coronavirus. Fortunately, the case fatality rate seems to be quite low, just a few percent.
In this the centennial year of the great 1918 pandemic, I was invited to speak at a special symposium on emerging infectious diseases at the renowned Pasteur Institute in Paris. One presentation that was both fascinating and alarming was on viruses in fish. I haven’t eaten raw fish since. When I heard that, in mid-December, a new form of pneumonia had struck a seafood market in Wuhan, central China, it seemed like a new fish disease affecting humans might have finally emerged. It turns out that the seafood market at the center of the outbreak also sold live animals and meat from wildlife such as snakes and marmots, and a wildlife primary infection source is most probable.