UPDATE Wuhan coronavirus - 2019-nCoV Q&A #6: An evidence-based hypothesis
Facebook Twitter LinkedIn EmailDr. Daniel Lucey, who has responded to, and monitored information on outbreaks since 2001, has provided a series of updates and analysis on the outbreak, now an epidemic of 2019-nCoV, the novel coronavirus identified in Wuhan China, since Jan. 7.
An Evidence-based Hypothesis that the Epidemic began in November 2019 or earlier and at a location other than the Wuhan Huanan seafood market: Major Implications.
Was Dec. 1, 2019 the earliest date of symptom onset for any of the 41 laboratory-confirmed patients reported in yesterday’s Jan. 24 paper by Huang C et al. in The Lancet titled: “Clinical features of patients infected with 2019 novel coronavirus in Wuhan, China”?
Yes. December 1. (This is new information. The prior earliest dates were Dec. 12, or Dec. 8).
Did this earliest of the 41 patients have any exposure to the Huanan seafood market?
No. (See article, page 3 Figure 1B timelines of illness onset for all 41 patients).
Did any of that patient's family members develop fever or any respiratory symptoms?
No. (see article page 4 Results section paragraph 2, lines 5-6).
Was any explanation given for how this patient became infected?
No.
Did this initial patient have any epidemiological link to the 40 later cases?
No. (see article page 4 “Results” section paragraph 2, lines 7-8).
On what date did the next 3 patients of the 41 patients have onset of symptoms?
December 10. (see article Figure 1B: 2 of these 3 patients had no exposure to the seafood market).
Did 14 of the 41 patients (34%) have no exposure to this seafood market?
Yes. (See figure 1B blue shading for patients with no exposure to the seafood market).
What explanation was given for the source of infection for these 14 patients with no exposure to the seafood market?
No explanation for 13 of the 14 patients was given. One of the 14 patients was the wife of the man who was the first fatality and who had “continuous exposures to the market (article, page 4, results section lines 8-13).
Based on the above data what hypothesis can be formulated?
Infection must have occurred in November, 2019 for the earliest reported patient with onset of symptoms Dec. 1. (The incubation is unknown, but assumed to be 1-14 days based on extrapolation from SARS (~1-10 days) and MERS (~2-14 days) coronavirus incubation periods). Whether this patient was infected from an animal or another person in November, directly or by fomites, his infection occurred at a location other than the Huanan seafood market.
Does this hypothesis propose that person-to-person transmission was occurring and/or animal-to-person transmission occurring, in November or earlier in 2019 in Wuhan?
Yes.
Where might animal-to-person transmission have been occurring?
Potentially at one or multiple places in the supply chain of the infected animals e.g., in one or more multiple markets, or restaurants, or farms, or with wild animals, legal or illegal trade.
What are some of the potential major implications of this hypothesis?
If initial and potentially repeated animal-person transmission, followed by subsequent person-to-person transmission, could have begun in October-November or earlier in 2019, then patients with pneumonia due to infection with the novel coronavirus (“2019-nCoV”) could have started to spread across Wuhan, and by infected-travelers leaving Wuhan to other locations.
How does this hypothesis explain why patients with this 2019-nCov pneumonia in October-November (or earlier) would not have been recognized?
Because of the concurrent prevalence of respiratory illnesses such as pneumonia.
How does this hypothesis explain the sharp increase in cases reported since Jan. 18?
Chinese investigators quickly began testing many patients with pneumonia in Wuhan, and beyond, using the new rapid diagnostic test that only became available in mid-January. Having, and rapidly deploying, the new rapid diagnostic test was a brilliant action to fight this epidemic.
How does this hypothesis help to explain the apparent rapid spread of the 2019-nCov across Wuhan and beyond, after its apparent initial emergence from the Huanan seafood market in December 2019?
The hypothesis is that the initial emergence of the virus was not the Huanan seafood market. Spread of the virus was already occurring person-to-person in October-November (or earlier) and gradually increasing into December. Thus, some of the 14 of the 41 patients who had no exposure to the Huanan seafood market (see page 3 Figure 1B) would be explained.
Thus, the presumed rapid spread of the virus apparently for the first time from the Huanan seafood market in December did not occur. Instead the virus was already silently spreading in Wuhan hidden amidst many other patients with pneumonia at this time of year.
Thus, some of the 14 cases with no exposure to the Huanan market out of the total 41 cases (see article page 3, figure 1B) could be explained by the pre-existing chains of transmission causing ongoing person-to-person transmission and/or transmission from infected animals (1 or more species) in other markets inside and/or outside Wuhan, or anywhere along the supply chain of infected animals.
How could a “look back” for infections during and before November be done and why do it?
Testing of stored human and animal specimens from 2018-2019 for both the virus itself and for antibody to the virus (as soon as sensitive and specific antibody tests are available in 2020).
In addition, one of the reasons to test immediately for the virus now in other animal markets, both multiple species and environmental testing, is to identify and shut down any other sources of recurrent transmission of the virus, both in Wuhan, Hubei province and other provinces in China, and neighboring areas where infected animal species could exist.
How could this hypothesis apply to the likelihood of successfully stopping spread of the virus by the control measures put into place after the (apparent) rapid increase in cases likely due partially at least to the use of the new diagnostic test in patients across Wuhan?
If in fact the virus was silently spreading unrecognized amidst other types of pneumonia in Wuhan, in the absence of a specific diagnostic test, for several months before its discovery in early January 2020, then the virus was already present across parts of Wuhan and other places in Hubei province, other parts of China, and even in limited numbers to some other countries. Thus, China could not have instituted earlier control measures against an undiscovered virus.
