Our daily comute to work, for many of us, is our first morning journey, however some of us travel from point A to point B during work, some of us can traverse many factories, shops and houses as part of our job. Interestingly many eventually will go to the supermarket, some daily, others weekly and others monthly depending on their personal planing, but we all need to eat! Even going beyond the supermarket, one needs to have lunch at work, where many go out of work to eat, use a canteen, eat in workplace or eat at home.
For those that eat in a canteen or go out to eat, a new norm seems to be growing with the COVID-19 pandemic.
Social distancing will be required for now on,
Maximum entrance capacity limit (no more crowded rooms),
The places we eat or get food are places of gathering, and they seem to be the perfect places to know where any virus lurks and is transmitting.
For these reasons my recommendation is to be cautious in these zones for they will be the zones with high probability of transmission.
As we enter in community spread, active suppression in these zone will have many advantages:
Stop mass community transmission,
Segregate positives and their relatives,
Get to know the transmission circuit
Since resources are limited suppression measures need to be used rationally, however if we get an idea of virus spread we can more actively direct our efforts. Since “feeding” zones are points of convergence it might well be a good starting point to statistically apply suppression methods, for any positive will give valuable information of virus infection state geographical localisation.
As the pandemic progresses every day, each government reports the number of infected persons per day, the number of deaths and the critical state patients. But how does the the governments get to know the numbers? Basically every time someone reaches the healthcare system, and is a suspect, they will be tested. If positive, he or she we will be counted as a new infection. Also if the healthcare system test individuals without a reason and are positive they will also be counted.
The accuracy of the numbers with this approach will depend on how the pathogen operates. If the infected person detects symptoms before spreading it and contaminating others, or the infected person dies, the numbers will be quite accurate.
However on cases that transmission time is large and asymptomatic most of the infection period, the reported numbers are unrealistic.
The COVID-19 pathogen combines three important behaviours:
It may or not produce symptoms;
While asymptomatic the virus can spread until about 14 days;
Produces symptoms similar to flue on mild to moderate cases and pneumonia on critical cases.
By the time the healthcare system detects a moderate or critical case, the infected individual has already spread the virus without knowing to many others… So the presented numbers will have a low correlation with the state of the spread.
Although the correlation isn’t the best, it is what’s possible to gather at the moment. I can imagine that the correlation will be higher in places the virus infects people which become moderate to critically sick. On places where the population is young, spread geographically and with an immune system capable to deal with the infection, might even pass unnoticed. The correlation will also improve if we test people as much as possible.
If 80% of the population has mild symptoms, these individuals do not go to the healthcare system and no preventive testing done, only 20% will actually call for help and be registered.
It is possible that values measured for total active cases of infection be 5 to 10 times higher than measured. This will depend on the aggressiveness of the virus and population fitness, considering we catch on the healthcare system 20% to 10% infections.
σ is our estimation ratio of the percentage of infected captured by the Healthcare system.
So multiplying the reported value by a number between 5 and 10 will give you a more accurate infection count.
I have been following with a bit of apprehension the COVID-19 pandemic evolution around the world, from Asia to pretty much all over the world. Human kind has lived and until now survived many epidemics and pandemics, but this virus seems to have taken everyone by surprise, where even many important nation representatives showed no interest in dealing with the pandemic calling it, a simple flue virus.
The pandemic, initiated in China Hubei Province in Wuhan. After a slow start by the Chinese governement to grasp the scale of the epidemic (at that time) it took tough measures, really going to extremes to contain the virus. It seems that their effort showed results and at this point China controlled the Pandemic in their territory but unfortunately has not solved the problem. Although the number of cases have reduced to zero, or almost there, it is sustained at high control and pressure measures. I can’t see any tourist wait 14 days quarantine to discover China, maybe only a few could afford it. Markets, shops, transportations services that serve millions will have to be limited.
Asian countries took the Pandemic seriously and prepared for the worst, closing borders, testing, isolating contaminated people and preventively reducing human circulation.
Europe on the other hand seems to be the new Pandemic center and Italy, it’s most affected country, having high number of deaths and many new infected cases every day. Throughout all Europe the pandemic seems to be growing without stop. It seems Europe took more time to implement hard measures and seems to be on the defensive side to reduce the number of new cases to avoid overcrowding their health care systems.
In the USA after a dangerous denial period the disease seems to be taking over and forcing many states to take hard measures, which in turn forced their president to declare national emergency. Interesting the UK and Brasil followed the American denial, however the growing numbers of infected people and deaths slowly but surely is changing state representatives opinion, that in turn make their presidents change stance.
In Africa we are starting to see a slow rise in cases, however numbers are expected to explode, in the comming weeks/days, for they do not have the capability that most developed countries have to deal with this pandemic.
This Pandemic, like any other can be dealt with mitigation actions like prophylactic containment and/or by suppression actions, which mainly consists of mass individual testing. The Asian countries and the Western countries are using different tactics to deal with the Pandemic. Asian countries use extreme mitigation actions combined with suppression actions which until now have proven to be effective. Interestingly the Western countries seem to be on the defensive side with mostly mitigation actions, with however not so effective results. A good explanation about this can be seen in the following link: https://www.theatlantic.com/ideas/archive/2020/03/how-we-beat-coronavirus/608389/
Interestingly Italy tried with very good results the usage of suppression actions on the pandemic but on a small scale. The difficulty to implement these actions on large cities with generalised infections is that it requires a great deal of resources and organisation. A good report on this subject can be seen here: https://www.ft.com/content/0dba7ea8-6713-11ea-800d-da70cff6e4d3
Certainly East and West have used models to predict the pandemic evolution, scientists, politics and the general community certainly got shocked when they noticed that doing nothing could yield total chaos. Models predict an insane amount of infected people at the peek of the pandemic.
The SIR model (S – Susceptible, I – Infected, R- Recovered) can help us understand the severity of our current world situation. For example for a 1 million population, 14 day mean recovery (time during which an infected individual can pass it on) and 0.2 value factor that compensates the rate at which an individual can come in contact with others, gives us a good prediction of what to expected of any epidemic response.
In this demonstration example case, almost all of the population gets infected and we get an infection peek of more than 20% of the population. No health care system can deal with such a wave.
I will end this post with a few questions that are in my mind so far:
Will the Western approach of low suppression (reactive to symptomatic patients) and high mitigation be enough?
Are the models used by scientists taking into account the fact that infected people don’t know they are infected and don’t present symptoms?
Even if we control the outbreak, how will the economy survive if most of us fear a second wave due to lack of immunity towards the virus?
How long can the world live in social containment?