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.
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.