In a comment below Thomascordatus asked me what I think about this video recorded by microbiologist Sucharit Bhakdi.

My first reaction is that as the former head of the Institute of Medical Microbiology and Hygiene, Prof. Bhakdi must know about what he is talking. According to Aelianus, that is the German in me. On the other hand, as a sort of scientist myself, I know that even renowned professors have been known to tell utter nonsense about a topic related to their field. Here are my thoughts:

It is true that we cannot know the true mortality rate, because we do not reliably know the number that is infected (which leads to overestimates, because those seriously ill are far more likely both to be tested and to die). It is also true that the mere presence of a virus infection in a person who then dies does not prove that they died FROM that virus. As is the case with influenza, it seems we will only be able to estimate Covid-19-related deaths after the epidemic is over, namely through ‘excess mortality’, i.e. deaths beyond the background mortality.

These arguments, however, do not explain away the fact that a number of regions experience a surge of severe respiratory illness that requires ICU care, to such an unprecedented extent that hospitals in these regions (first Hubai, later Lombardy, the northeast of France, Madrid) are utterly swamped . There must be some reason for this, and if a large number of these patients tests positive for SARS-CoV-2, this seems to indicate some causality.

So we have an easily spread virus (easily spread particularly since (still) asymptomatic patients can transmit it) in a population with little if any immunity against it. I have not yet heard any experts who claim that it will not infect the majority of people (although I stand to be corrected). Even if the proportion of infected people requiring ICU treatment is much smaller than current infection number suggest: As long as the virus spreads exponentially (which it appears to do, and what you’d expect it to do), the number of these cases should also increase exponentially. In Italy, currently 0.1% of the population have been tested positive for SARS-CoV-2. Even if this underestimates the actual infections by a factor of 100, there would still only be a 10% infection rate and rapid growth of infections as well as severe cases should still be expected. Incidentally, according to this, while 22.7% of Italian tests were positive as of 20th March, this was true only for 3.9% of tests in Germany (15th March) or 5.3% of tests in the UK (20th March). In all cases, tests were restricted to probable cases (symptoms and/or close contact to infected person), so the proportion in the general population should be far lower.

For me, it is the very real risk of overwhelming the health care system that makes it sensible to slow down the spread of SARS-CoV-2 at this point. A Spanish report of 22nd March looks at the age distribution of confirmed SARS-CoV-2 infections, of deaths among these, and of treatment in the ICU. Of the infected, 62% were younger than 60; of the deaths, only 3.3%. However, 32% of the ICU patients were younger than 60, and the majority of these, apparently, did not die. In fact, hardly any of the over 80-year-olds, who made up two thirds of the fatalities, had been treated in the ICU at all. This indicates to me that having sufficient ICU capacity for all severe cases will save lives, and that especially among younger people, among whom it is far more likely that any acute severe respiratory illness is actually caused by SARS-CoV-2 and who would not ‘have died anyway from something else’.

Related to this, I have not found out where Prof. Bhakdi gets his number of 99.5% of infections of whom he says that they may be ‘infected’, but they are ‘not ill’. The only numbers I found are from a WHO report based on data from 55924 confirmed infections up to 20th February. Of these, 80% were ‘mild to moderate’ – which, however, does include pneumonia, unless it requires hospitalization. A proportion of 88% had a fever, about two thirds a dry cough. This may not be dangerous, but I still would not say that they are not ‘not ill’. The same report speaks of 13.8% of ‘severe’ cases, which means ‘dyspnea, respiratory frequency ≥30/minute, blood oxygen saturation ≤93%, PaO2/FiO2 ratio <300, and/or lung infiltrates >50% of the lung field within 24-48 hours’, and 6.1%  ‘critical cases’, namely ‘respiratory failure, septic shock, and/or multiple organ dysfunction/failure’.

It is open to debate which measures will buy us the needed time to spread out the cases requiring ventilation, to increase production of needed materials and, if possible, intensive care capacity, without causing more harm socially, economically and regarding other health conditions. I just think ‘this is all utterly unnecessary’ is not correct.