COVID-19 crossing the Rubicon

As far as I can make out, Australia is now fully committed to a policy of "Adapt and Control" as opposed to "Eradicate".

This means infection rates will continue to grow, at first gradually and then suddenly.

The intention is to avoid the hospitals being overwhelmed while gradually lifting restrictions to get people back to work.

There is already an increase in the reproduction rate, "R", above 1, from the reduced physical distancing that inevitably followed the announcements of success and plans to remove restrictions. It started rising weeks ago, which was triumphantly announced as still being below 1.

That growth is starting from a very low rate of community transmission, so the growth will initially again be "gradual". But community transmission means untrackable and uncontrolled transmission. "Community" transmission is not stopped by testing and contact tracing because the carriers are often pre-clinical and don't get tested. It is only limited by physical distancing preventing transmission. Lifting the restrictions simply means there is nothing to prevent community transmission growing again, at first gradually and then suddenly. This shows up weeks later as the numbers of known cases growing gradually and then suddenly and later still for the numbers of deaths.

Opening the schools removes the main obstacle to getting people back to work and at the same time opens a channel for wider spread of infections among households via schools even while the faster transmission between households via workplaces remains restricted.

As infected school children tend to have mild or no symptoms it is likely that they are less infectious and so transmission between them in schools would be relatively slow compared with transmission between adults at workplaces. That has been presented as though a slow rate of transmission means a decline in cases – with "evidence" such as the low numbers of clusters among school children and of household transmission from children to adults. But we don't know much about mild or asymptomatic cases because pre-clinical cases obviously do not get much clinical study since they don't seek clinical assistance. If some of them last longer than more severe cases that trigger an immune system response or result in long term carriers, then a slow rate of transmission can still result in a larger than 1 rate of reproduction, sufficient to cause a (slower) epidemic.

But we don't actually even know whether or to what extent infected children are less infectious than infected adults. Droplets are the main source of contagion, direct and via surfaces with transfer from hands to face. One would certainly expect that to be greater with symptoms such as coughs and sneezes that actually project droplets. Hence the emphasis on physical distancing together with washing hands and covering coughs and sneezes. Aerosol transmission by simply breathing is mainly known to be important in a healthcare setting where there is continuous close contact with infected patients. But aerosol transmission is important enough that religious ceremonies now permitted even in confined spaces in Germany are not permitted to sing. Singing projects larger quantities of virus into a confined space than merely breathing or talking, even though it does so less than coughing or sneezing. The cumulative effect of being confined in the same classroom as an infected child for hours each day over several weeks is simply not known.

The available evidence is quite sufficient to convince everybody who is utterly determined to get kids back to school so that their parents can get back to work. They are all chanting about it in unison. But since they live off other people's work their livelihoods depend on them not understanding.

For example the livelihood of lobbyists for pubs depends on believing that a pub could maintain social distancing of 1.5m between customers if it was permitted to cram them in at 1 per 2 square metre instead of the current limit of 1 per 4. Consequently they can adamantly demand that the number allowed in be doubled so that they might be able to reopen some pubs. It simply does not matter that it would be physically impossible for anybody to get in or out. Their role is to lobby, not to understand things that their livelihood depends on them not understanding.

Rather more evidence should be needed to convince others. Why should one expect to have seen clusters among school children, given that children were withdrawn from schools well before governments shut them? Why would one expect a child to be reported as the first case in a household given that they usually only have mild or no symptoms? I would expect the first case reported to be someone with more severe symptoms who got tested as a result, with any child in the house subsequently found to be infected likely to be recorded as only as a subsequent case assumed to have been infected by the adult.

School childrn will now be spending many hours a day in the same confined classroom space with a cumulative effect on other children and teachers. So it may be possible there could be a gradual but substantial increase in the numbers of infected children before there is enough onwards transmission to more severe cases among teachers and households for this increase to be picked up from surveillance testing and contact tracing.