First up, February 4:
Experts envision two scenarios if the new coronavirus isn’t contained
With the new coronavirus spreading from person to person (possibly including from people without symptoms), reaching four continents, and traveling faster than SARS, driving it out of existence is looking increasingly unlikely.
It’s still possible that quarantines and travel bans will first halt the outbreak and then eradicate the microbe, and the world will never see 2019-nCoV again, as epidemiologist Dr. Mike Ryan, head of health emergencies at the World Health Organization, told STAT on Saturday. That’s what happened with SARS in 2003.
Many experts, however, view that happy outcome as increasingly unlikely. “Independent self-sustaining outbreaks [of 2019-nCoV] in major cities globally could become inevitable because of substantial exportation of pre-symptomatic cases,” scientists at the University of Hong Kong concluded in a paper published in The Lancet last week.
Researchers are therefore asking what seems like a defeatist question but whose answer has huge implications for public policy: What will a world with endemic 2019-nCoV — circulating permanently in the human population — be like?
Related:
This VC firm once pledged to never invest in health care. Now it’s launching its third life sciences fund
“It’s not too soon to talk about this,” said Dr. Amesh Adalja, an infectious disease specialist at the Johns Hopkins Center for Health Security. “We know that respiratory viruses are especially difficult to control, so I think it’s very possible that the current outbreak ends with the virus becoming endemic.”
Experts see two possibilities, each with unique consequences:
Just another coronavirus
2019-nCoV joins the four coronaviruses now circulating in people. “I can imagine a scenario where this becomes a fifth endemic human coronavirus,” said Stephen Morse of Columbia University’s Mailman School of Public Health, an epidemiologist and expert on emerging infectious diseases. “We don’t pay much attention to them because they’re so mundane,” especially compared to seasonal flu.
Although little-known outside health care and virology circles, the current four “are already part of the winter-spring seasonal landscape of respiratory disease,” Adalja said. Two of them, OC43 and 229E, were discovered in the 1960s but had circulated in cows and bats, respectively, for centuries. The others, HKU1 and NL63, were discovered after the 2003-2004 SARS outbreak, also after circulating in animals. It’s not known how long they’d existed in people before scientists noticed, but since they jumped from animals to people before the era of virology, it isn’t known whether that initial jump triggered widespread disease.....MUCH MORE
OC43 and 229E are more prevalent than other endemic human coronaviruses, especially in children and the elderly. Together, the four are responsible for an estimated one-quarter of all colds. “For the most part they cause common-cold-type symptoms,” said Richard Webby, an influenza expert at St. Jude Children’s Research Hospital. “Maybe that is the most likely end scenario if this thing becomes entrenched.”
All four, in particular HKU1, can cause pneumonia, and sometimes death. It is rare enough that researchers do not have good estimates of its prevalence or virulence, but two of the others have been better studied. In one of the few close looks at OC43 and 229E, researchers measured their infection rates during four winters (1999-2003) in Rochester, N.Y., among 2,897 healthy outpatients, adults with cardiopulmonary disease, and patients hospitalized with acute respiratory illnesses.
They identified 398 coronavirus infections (four people had both OC43 or 229E). Infection rates ran from 0.5% among healthy elderly adults to 15% among healthy young adults (where “healthy” means they had no viral symptoms), with the highest rates coming in the winter of 2000-2001, for no obvious reason — suggesting that coronavirus infection rates will rise and fall unpredictably, much like seasonal flu, and that its consequences will also be similar: some serious illness, some mild, and a lot of asymptomatic infections.
The most common symptoms were runny nose, cough, and congestion, for about 10 days; no one even ran a fever. All told, 35% of infections with 229E and 18% with OC43 were asymptomatic. “Asymptomatic infection … [meaning] without respiratory symptoms was fairly common,” the authors concluded.
But sometimes symptoms were nothing to sneeze at. There were 96 coronavirus infections among the 1,388 hospitalized patients. OC43 caused more severe disease than 229E, requiring intensive care for 15% of those infected. About one-third of the patients admitted to the hospital with either coronavirus developed pneumonia; one of the 229E patients and two of the OC43 patients died.
On the bright side, if a coronavirus infects enough people regularly there will be greater business incentive to develop a vaccine and other countermeasures. That never happened with SARS because it died out, leaving no market for such products.
On the decidedly darker side, a fifth endemic coronavirus means more sickness and death from respiratory infections.
Odds: Moderate. “I think there is a reasonable probability that this becomes the fifth community-acquired coronavirus,” Adalja said, something he expanded on in his blog. Webby agreed: “I have a little bit of hope that, OK, we’ll put up with a couple of years of heightened [2019-nCoV] activity before settling down to something like the other four coronaviruses.”
2019-nCoV returns repeatedly like a bad seasonal flu
The “seasonal” reflects the fact that viruses can’t tolerate high heat and humidity, preferring the cool and dry conditions of winter and spring, Webby said. That’s why flu, as well as the four coronaviruses, are less prevalent in warm, humid months. If the new coronavirus follows suit, then containment efforts plus the arrival of summer should drive infections to near zero.
But also like flu viruses, that doesn’t mean it’s gone.
The “bad” reflects the fact that the number of 2019-nCoV cases and deaths so far suggests that the new coronavirus has a fatality rate around 2%. That’s almost certainly an overestimate, since mild cases aren’t all being counted. But even 2% is less than SARS’ 10% and nowhere near the 37% of MERS (Middle East respiratory syndrome coronavirus). On the other hand, seasonal flu kills fewer than 0.1% of those it infects, though that’s still tens of thousands of deaths a year just in the U.S. The global disaster that was the 1917 “Spanish flu” pandemic killed 2.5% (though some estimates exceed 10%)....
And ten days later, February 14, 2020:
Disease modelers gaze into their computers to see the future of Covid-19, and it isn’t good
At least 550,000 cases. Maybe 4.4 million. Or something in between.....MUCH MORE
Like weather forecasters, researchers who use mathematical equations to project how bad a disease outbreak might become are used to uncertainties and incomplete data, and Covid-19, the disease caused by the new-to-humans coronavirus that began circulating in Wuhan, China, late last year, has those everywhere you look. That can make the mathematical models of outbreaks, with their wide range of forecasts, seem like guesswork gussied up with differential equations; the eightfold difference in projected Covid-19 cases in Wuhan, calculated by a team from the U.S. and Canada, isn’t unusual for the early weeks of an outbreak of a never-before-seen illness....
STAT's Coronavirus Coverage
See also February 9's:
The Journal Nature Has Dropped Its Paywall for Coronavirus Reporting and Research
