For a week or so I have been fearing this potentially deadly disease spreading to most people on Earth (space-station and antarctic bases excepted), since the doubling time has been about half a week, and simple calculations show that even with a 1 week doubling time, half the Earth's population would get it by June. My fears were confirmed by reading of the John Hopkins Event 201 simulation last year, in which a 1 week doubling time virus spread throughout the world and killed tens of millions of people:
There is no precedent for a virus spreading as fast and far as this one:
I still believe the Wuhan coronavirus will infect half the population by the middle of this year, but I now have cause for hope that the variants which do this will be far less virulent than the one or ones which caused the deaths in Hubei in January.
I am not an epidemiologist, but here goes. I am suggesting that the virus is mutating rapidly into less virulent strains which compete successfully against the original, December and early January, more virulent form(s). However, I know of no reports of such mutations.
From the John Hopkins ticker (necessarily long URL):
here are the figures from Hubei, the province containing Wuhan, and the ten provinces with the highest death rates, all of which were infected in mid to late January, about 5 or 6 weeks after the disease began in Wuhan. (The following is a table, to be viewed in a fixed width font.)
Province Confirmed Deaths Recovered Hubei 11,177 350 3.1% 295 2.6% Guangdong 725 0 15 2.1% Zeijiang 724 0 36 5.0% Henan 566 2 0.3% 14 2.5% Hunan 521 0 22 4.2% Anhui 408 0 11 2.7% Jiangxi 391 0 18 4.6% Chongquing 312 2 0.6% 8 2.7% Jaingsu 271 0 8 3.0% Shandong 259 0 6 2.3% Sichuan 254 1 0.4% 14 5.5% Average of 0.113% 3.430% these 10 provinces
The lower death rate in the provinces which were first infected well after the initial spread in Hubei is striking: it is 1/27th the death rate in Hubei.
The reasons for this might include:
1. Cases in the other provinces are, on average, more recent than those in Hubei, meaning the death rate will rise over time to resemble that of Hubei (and the Hubei death rate could rise too, for the same reason.)
2. Saturation of hospitals and testing in Hubei and Wuhan in particular.
3. The provinces being infected more with a less symptomatic and so less deadly variant of the virus than those which caused the initial spread in Hubei, though hopefully the same process would be occurring in Hubei too, so the death rate for recent infections would be lower too. (I hope this is happening.)
4. Nursing leading to people surviving to the extent that a significantly lower proportion of people have no immunity. (I think this does not yet play a significant role.)
5. Poorer quality of care, including people not being able to get into hospital, in Hubei compared to the other provinces
However, I can’t imagine that 1, 2 or 4 would make anything like the difference we see - a striking 27:1 ratio in the death rate. 5 might explain some of it. This makes me think that 3 is true to a significant degree.
Now turning to the recovery rates. The other provinces have a significantly higher recovery rate than Hubei. Assuming the diagnostic standards do not vary significantly, this cannot be explained by 1, 2 or 4. It would be very well explained by 3.
In the other provinces, the recognised infections seem to be less damaging, with quicker recovery. Assuming that quality of care is about the same, the only explanation I can think of is that these more recent cases in the other provinces are with variants of the virus which cause less symptoms and perhaps lead to an earlier recovery - while still being contagious enough to compete successfully against the original and/or any more recently mutated, more virulent strains.
This analysis gives me hope that by the time the virus reaches about half the people on Earth - as I believe it will by the middle of this year - that the variants most people get will be much less damaging than at the start of the pandemic.
If this analysis is true, then the true rates of infection in the other provinces - and recently in Hubei - may be much higher in proportion to the number of confirmed cases than was the ratio a few weeks ago. This would be due to a greater proportion of infected people having no or only mild symptoms - so they are never tested or recognised much by the medical system.
If this is occurring, then it may work out well . . . unless there are mutants which remain highly infectious but which have sufficiently different spike and envelope proteins that the antibodies developed in response to the current strains are ineffective. Then those strains might start a whole second wave of infection, since immunologically, they would be a different virus.
If this analysis is correct, then while the Chinese lockdown (which is unsustainable) may slow the spread of the virus more effectively than the post-symptom quarantine arrangements of the West (which is the best they can do, not being a dictatorship), the Western approach is actually more helpful. This would be due to the Western approach enabling strains of the virus which have few or no symptoms to spread very rapidly, while significantly reducing the replication of strains which produce strong enough symptoms for people to be hospitalised and tested.
If there were no such helpful mutations, then the Western approach would be less effective than the Chinese approach, but the Chinese approach is unsustainable for more than a few weeks. There's no hope of a conventional vaccine by the middle of this year, or even the end. However, if my analysis is correct, then by the good fortune of the virus mutating without altering its envelope and spike proteins significantly, the most successful strains become less damaging and work like a vaccine against the more damaging strains.