A statistical study from highly credentialed Chinese academics estimates the virus has an RO (R-naught) of slightly over 4, meaning every carrier infects four other people on average.

This is very high. Run-of-the-mill flu viruses average about 1.3 (i.e. each carrier infects 1.3 other people while contagious).

By the time the initial individual carrier from Wuhan develops symptoms, the virus has already gone through two geometric expansions and everyone infected has no idea they even have the virus.

Common sense suggests that airplanes, airports, crowded markets, elevators–any confined space where a number of people might pass through a two-meter contagious circle around the carrier– might result in a contagion rate far above 4.

Coronaviruses tend to be contagious in relatively close contact (within two meters / six feet) but masks may not be enough protection, as it may spread by contact with surfaces and through the eyes.

All available evidence supports the conclusion that this virus is highly contagious.

Along with its contagiousness, the most consequential feature of this virus is that asymptomatic carriers can transmit it to other people, who will also be unaware they’ve been infected with the pathogen.

Authorities are like the officers on the Titanic who were tasked with both reassuring the passengers everything was under control and urging them into the lifeboats: you can’t tell everyone the risk is low and everything’s under control but it’s also high enough that you better get in a lifeboat. This is a classic double-bind. In the confusion, few understand the risk remains high and act accordingly.

The horse already left the barn a month ago, and so closing the barn door now has little effect. Five million people already left Wuhan and tens of thousands have already traveled to dozens of other countries. The virus can no longer be contained with half-measures. Yet half-measures are all the authorities are willing to impose.

Those expecting the virus to burn itself shortly must assume that the virus will not mutate into a more contagious or deadly form, even though viruses mutate at very high rates: the more people carry the virus, the greater the opportunities for a mutation to occur that can be spread to other hosts.

Neither is the expectation that an effective vaccine will be ready for mass inoculations in a month or two. Realistic timelines for an effective vaccine are four to six months for development of a vaccine, then additional months to test its safety and effectiveness and more months if all goes well to produce hundreds of millions of doses of the vaccine, and then more time to distribute the vaccines.

It’s natural to grasp at straws in crisis, and natural to take every false dawn for sunrise. Announcements that the rate of infection is slowing will be taken as evidence the virus will soon be completely under control, when a decline from RO 4 to RO 3 or RO 2 doesn’t mean the virus is about to disappear; all it means is the rate of expansion has declined. Premature announcements of a cure will encourage a complacent expectation of a quick return to “normal life” that will be severely challenged by the “Wave Two” global expansion of the virus.

The economic, political and social consequences of the extreme measures required to control the spread of the virus (total lockdown of an entire country’s transportation systems)–or the failure to pursue such extreme measures, enabling the spread of the virus–are the second-order effects I’ve been exploring in recent blog posts: consequences have their own consequences.

The epidemic’s extent will depend on a number of factors, including when infected individuals become contagious, how long they remain contagious and how long the virus can survive outside a human host.

However, one estimate predicts that the total number of infections in five major Chinese cities — Beijing, Shanghai, Guangzhou, Shenzhen and Chongqing — will peak between late April and early May, according to a model developed by researchers at The University of Hong Kong.

Mainland officials earlier said that unlike severe acute respiratory syndrome (Sars) the new coronavirus was infectious during the incubation period. Those infected with the virus might not immediately show any symptoms.

Just as an estimate – at the height of the epidemic, as many as 150,000 new cases would be confirmed every day in Chongqing (a megacity in southwest China), because of its large population coupled with intense travel volume with Wuhan.

If we accept what is known about the virus, then logic, science and probabilities all suggest we brace for impact.