Few days ago I read an interesting article by McKinsey: “How might the Covid-19 pandemic end“, resulting from interviews to several people in industry plus a few experts in epidemics.
One point that impressed me is the evaluation of the economic cost, somewhere between 16 trillion to 35 trillion $ (for US) by 2025. The range estimated is pretty wide, meaning that we do not have a clear idea of the economic impact, but even if one takes the lower figure it remains a staggering huge impact. Interestingly, it is also pointed out that one day of lock-down costs 12 billion $ for the US economy, testing 20 million US citizens (6% of the population) has a cost around 20 million $ and this is the level of testing required to avoid a generalised lock-down. Looking at the figure it seems like a no brainer to go for massive testing rather than locking down the Country. The problem, of course, is to determine the 20 million Americans that need to be tested and organise the logistics to support this. Also notice, it might seem obvious but the more I read newspapers and talk to people, the more I realise it is not, that all these cost will have to be covered, one way or the other. I see a widespread feeling that to recover from the economic impact of Covid we are being given “free” money from Governments and Institutions. There is not such a thing as free money. What is happening is that Governments have agreed to expand the debt, meaning that we, and our kids, will have to repay those debts in thee coming decades. The McKinsey article is evaluating the debt for each US family in the order of 26,000$.
We are pretty sure that by vaccinating all world population in a matter of weeks we would be able to stop Covid-19 once and for all. Unfortunately it is impossible to carry out a worldwide vaccination in a matter of week … as well as to convince all people to get vaccinated.
Epidemics fade away once a herd immunity is reached. The percentage of people that have to become immune in a given population to reach herd immunity depends on the “virulence” of the virus: the formula is:
Hi= 1- 1/Ro
were R0 is the “basic reproduction number”, representing the number of people one infected person would infect (assuming no precautions are in place). From this formula (if you do the math) it is clear that the more virulent a virus is (the more people one infected person is likely to infect)the higher the number of immune people needed to reach heard immunity. In the case of Covid-19 this percentage is somewhere between 70 to 80% of the population (meaning that 70 to 80% of the population has to be immune -either because vaccinated or because having healed from the infection).
Here lies the problem: the percentage of a population assumes a stable number of people (the so called susceptible cases) but this assumption does not hold true in our world. You can have a 70% people vaccinated/recovered in Italy (target end of September) but then you have tourists and business people crossing the boundary and altering the path of infection. There are no more closed sets in the world, islands separated by impassable seas. We have a continuous flow of people from one point to another. The world is no longer an ensemble of island, is an overlapping set of islands where Sydney Australia is right beside Rome Italy, no distance in between to separate them.
Reaching a theoretical herd immunity in Italy and having no herd immunity in Africa means having no herd immunity in Italy as well!
The people interviewed by McKinsey pointed out the need to take a broader approach to epidemic control where vaccination is an important component but it cannot be the only one. Testing and tracking are another crucial component. Here again we cannot test everybody everyday: we need to make educated guesses on infection probability and test those that might be (likely) infected.
Technology can help a lot, actually it might be the only way to solve this problem. At the Digital Reality Initiative we have pointed out the usefulness of Personal Digital Twins as a technology that can help tracking potentially infected people preserving privacy (up to a certain level). The cyberspace has no boundary, just like the world we created with massive people movement: we need to leverage on data in the cyberspace to fight the epidemic.