covid-19 Update mid-November 000

I am still reading and not yet able to write a persuasive article.

But here’s my tentative view on current developments.

Victoria having zero “mystery cases” over fourteen days is a significant milestones achieved earlier than hoped for in the original “Roadmap”. Far more significant than the other two zeros – daily average cases and deaths. But 000 is still an “emergency”, although no longer a “disaster”.

The problem is that while things remain “as good as it gets” and even after the numbers start to rise, more and more people will act as though the emergency is over and ignore the monotonous repetion of official advice that it isn’t.

I did not expect zero “mysteries” over 14 days would be reached at all, because partially lifting restrictions in October would slow down the reduction in transmission prolonging the lockdown until it was abandoned without having actually eliminated community transmission.

I still think that happened – the restrictions were lifted too early so that the risks were not minimized. If lockdown had been maintained until 28 days with no “mystery cases” we could be significantly more certain of having eliminated community transmission.

But it is now plausible that 28 days could be achieved despite opening up. Even if 28 days was achieved there would still be some risk but it would be reasonable to describe as “minimal” in a context where the risk of outbreaks seeded from elsewhere would be much more important.

I still don’t expect that we will reach 28 days. But they have certainly achieved what they setout to do with an “aggressive suppression” strategy far closer to New Zealand’s elimination than the national framework.

The risk is now minimal in the sense that outbreaks that end up in a third wave that needs another lockdown are more likely to start in other Australian States than from residual local transmission in Victoria.

That may well be “as good as it gets”.

Certainly it is a good time to enjoy the opportunities available outdoors. (I have even had my annual haircut and beard trim!).

But precisely because people will indeed do so and opening up will accelerate, it is reasonable to expect that any residual transmission chains will become much harder to suppress when they eventually do become visible. It won’t get better over time.

While it is possible there may currently be none at all, I think it is far more likely that the remaining transmission chains would simply be harder to detect.

For example asymptomatic cases among school children could continue for quite a few generations before eventually some older person such as a parent or teacher becomes ill enough to get tested. If it happens to be a household in precarious employment, living in a community with a high proportion of other such households, it could be a few more generations before anyone gets sick enough to turn up at a hospital where they would certainly be tested. Because nobody has turned up at a hospital or other testing in 14 days we can be reasonably confident the numbers out there are quite small. With small numbers the stochastic character can either result in transmission dying out completely or exploding to higher numbers. The more the small numbers are in contact with others because restrictions have been lifted the higher the chances of transmission exploding.

Contact tracing works very well during lockdown because people have few contacts and know who or where they are.

After opening up it becomes a repeated game of “whack a mole” as in the “gold standard” of NSW. Note also today’s “mystery” in South Australia.

With greatly upgraded contact tracing and testing efforts, as well as slowly decaying compliance with physical distancing, registration etc, it will be quite feasible to deal with occasional, sporadic outbreak with a minimal risk of it spreading.

Then it is simply a matter of how many weeks you repeat taking that “minimal risk” before you end up needing to go into “surge” mode after more than 4 new confirmed cases (not in quarantine) per day per million population. Then how many times you repeat that risk of a surge before ending up exceeding surge capacity at 10 times that rate of new cases (40 per day per million) and having to go back into lockdown. See targets in:

https://www.health.gov.au/resources/publications/national-contact-tracing-review

I don’t think there is much risk of Australia ending up in the same situation as Europe or North America, let alone the rest of the world. When an Australian surge gets out of control at 40 cases per day per million, there should still be plenty of time before hospitals become overloaded for another lockdown to prevent that. (Victoria came nowhere near hospital overload despite delay in locking down resulting in 800 deaths from a peak of 750 cases per day).

How likely such a third wave is depends on how long before a vaccine has sufficient impact on transmission to eliminate the risk. (It also depends on many other factors, many hard to model).

Recent announcements suggest Australia could achieve herd immunity from vaccines by the end of next year.

It will certainly take a lot longer than that before the whole world has achieved eradication. I will discuss that and other issues such as testing etc in later articles.

I am certainly not in a position to estimate the probabilities of a third wave and lockdown in Australia better than the public health advisors who have been doing so.

But from what I have seen published about the models, I seriously doubt that they are in a good position to estimate either. Certainly their commitment to “stay open” hinders accurate estimation of when it becomes necessary to lockdown again.

That will also have to be for a later article.

Meanwhile, it is worth remembering that we are much less than half way through if it ends by the end of next year.

Some reduction in risk of transmission would result from the first tranche of vaccines targeted at Health and Aged Care workforces and others likely to be exposed and to expose others. But don’t assume a production line for vaccine and vaccine imports will produce a steady output of vaccine imports until herd immunity is achieved by the end of next year.

In fact the pilot plants for phase 3 testing have already continued production and some supplies may be available (elsewhere) as soon as approval is rushed through, perhaps even this month. The first mass production plants will also come onstream shortly after. But the requirement is for literally billions of doses.

I would assume there would be a classic “acceleration” as plants are first built to produce machines (bioreactors etc) and raw materials and train high tech workforces for new plants. Risks of a third wave might be significantly reduced when only half the population has immunity.

But don’t assume that occurs half way through next year. If the exponential growth doubles output each month then the half way point could be November next year with 100% following a month later.

Priority in deliveries should go to the poor countries that will be in a desperate situation by then. Australia with relatively few cases has major reponsibilities to assist others far worse off in our region, such as Papua New Guinea and Indonesia.

More likely the queue will be allocated supplies according to capacity to pay rather than need. Certainly individuals who can pay premium prices will be vaccinated before those given free supplies as a public health measure. There will be free distribution as a public health measure within capitalism, but there won’t be fully prioritized distribution according to need.

But the plants located in Europe and North America will have plenty of demand from local States that have far greater need than Australia and also have the capacity to pay for what they need.

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