The Checkpoints are taken down ...
Thumbs up in Wuhan. The Checkpoints are taken down, travel restrictions are eased. The city hardest hit by the epidemic is slowly returning back to normal. Elsewhere in the country, other cities have been easing control measures. China has reported no new domestic cases for three days now.
The China viral episode is marked as a twelve week cycle, a perfectly "normal" pattern of viral distribution. The critical phase, the six week "quarantina" phase lasts six weeks. 95% of cases, (within two standard deviations of the norm), occur in this critical phase.
Should we be surprised by this? Not really. Quarantina
is the Venetian word for forty days. Forty days was the period of
isolation for new ships arriving at port in the 14th century. Michael Levitt, the British American Israeli biophysicist, predicted the epidemic would disappear from China by the end of March. The Nobel prize for chemistry was the scientist's prize in 2013. His speciality is not epidemiology nor virology. For Michael Levitt, modelling the viral epidemic is a numbers game and a pretty simple numbers game at that.
Levitt explains, "In exponential growth models, you assume that new people will be affected every day because you meet new people. But most of us meet the same people every day. You may meet new people on the bus or in public places but gradually most people will be infected or immune".
To stem the epidemic, in the absence of vaccine, the virus must be starved of victims to limit the outbreak. The government may claim we have moved from the containment phase to the delay phase but this is not correct. Home isolation and social distancing are measures to contain the virus, there can be no delay. The viral episode self extincts.
Neither can we flatten the curve. We can lower the peak of the outbreak by imposing radical social distancing measures and other "non pharmaceutical interventions". A viral spread is a mathematical function with three critical ratios, the infection rate, the reproduction ratio R(0) and the fatality rate.
Assuming an R(2) ratio, ie patient zero infects two people, then 2 people infect 4 people and so on, in a population of 100 people, the virus runs out of victims after just five steps. Then the case load falls, just as dramatically as it has risen.
In our C19 tracker we analyze the daily situation reports published by the World Health Organisation. Italy recorded over 5,000 cases yesterday. We are anxiously waiting for the tide to turn. The next few days will be critical. For Korea and Iran, along with China, it would appear the worst is over.
In the UK,. the numbers will escalate rapidly in the days ahead. Further social distancing measures may be announced. It is important to watch the data to call the move. The worst could be over by the end of April, the all clear sirens may be heard by the beginning of June ... Our people must be told there will be an end to this ...
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