Discussions emphasising 'COVID19 is more serious than flu' will probably become moot in the coming days and weeks, and for many people already have, but in case you are engaged in them, I would consider trying to get accurate numbers for flu, and to make some general points. 1/n
First off, flu mortality is sufficiently low that it is hard to measure, and requires a degree of modelling just to get at. That in itself tells you something. 2/n
Second, the vast majority of flu cases are not reported or diagnosed, so data are pieced together from various surveillance systems and studies. 3/n
However, total mortality (amongst whole population, not just infected) can estimated. An excellent recent review puts total mortality at 5.9 per 100,000 people per year, across continents and across years ncbi.nlm.nih.gov/pmc/articles/P… 4/n
Most serological studies put the annual proportion infected by flu at about 15%, though quite variable year to year. That would imply that 40 people die per 100,000 people infected, give or take - a infection fatality rate of 0.04% 5/n
Experts such as @LoneSimonsen2 may have more accurate numbers. 6/n
@LoneSimonsen2 In addition, many of these cases are older, and cause of death for those in end-of-life-care for example may be rather philosophical. 7/n
@LoneSimonsen2 In the context of COVID-19, I don't think it is worth the effort to belabour these comparisons, though they do serve as useful reference points to start a discussion about the seriousness of the situation. 8/n
@LoneSimonsen2 Also, whilst I understand the concern about getting reliable infection fatality rates for COVID-19, these will vary by space and time according to hospital capacity, and also vary by age. The % of cases that are serious and require hospitalisation is also of concern. 9/n
@LoneSimonsen2 The short conclusion is: COVID-19 has the potential to cause an epidemic incomparable to seasonal influenza, both due to higher per severity per infection, and due to potential for extreme stresses on hospitals. However, a large epidemic is not unavoidable. 10/n
@LoneSimonsen2 Controlling the epidemic may require very difficult interventions, and cause considerable disruption, as we have seen in China and other Asian countries. Epidemiology is a set of methods that will allow us to refine our interventions, to zoom in on those that work best. 11/n
@LoneSimonsen2 Patient management and treatment will improve over time, especially if numbers are kept manageable. Awe inspiring efforts are under way to develop vaccines in record time. The challenge is to keep transmission not to zero, but down to levels that don't grow exponentially. 12/n
@LoneSimonsen2 Early data show that R0 was about 2.5 in a population that had no information about what was happening or the seriousness. The aim is to reduce that to keep it below 1. That means using all interventions we have to reduce transmission by more than 60%. 13/n
@LoneSimonsen2 That seems like a really challenging task - but not an impossible one. To reduce transmission by more than 60% to keep the reproduction number below one, and prevent exponential spread. Several countries have now seemingly managed it, at least for a time. 14/n
@LoneSimonsen2 So the question seems to be, how can we sustainably achieve that level of reduction in transmission, to buy time for vaccine? (I wasn't intending such broad thread - happy to correct, elaborate, and clarify.) 15/n
