r/askscience • u/Alaska_Jack • Jun 24 '20
COVID-19 Can we accurately measure the death toll from COVID by simply comparing the death rate for the last few months to the death rate from previous years? Is that where the 120,000 figure comes from? If not, what are the problems with this approach?
Please forgive me if this is an ignorant question. It is an approach that makes sense to me, but it occurred to me that perhaps there is some problem with this approach that I have not considered.
9
u/PHealthy Epidemiology | Disease Dynamics | Novel Surveillance Systems Jun 24 '20 edited Jun 24 '20
"Accurately" is a bit of a nebulous term in epidemiology. To detect anomalous deaths in a population, yes. This is seen in the CDC excess deaths graph found here.
But accurately in the sense of large outbreaks with a large networks of hospitals/labs reporting tests then seasonal influenza is a good surrogate. CDC describes how there are issues with testing, reporting, and timeliness. The CDC instead uses sentinel sites where there is very accurate reporting and then models can be built to infer what's happening in the rest of the country.
Foodborne illness is another great example and also why our tax dollars pay for FoodNet, this sentinel site surveillance is again used to measure and then model to the rest of the country. You can contrast this with passively collected laboratory data which is much cheaper to collect but isn't near as complete.
CDC luckily has active case surveillance up and running so the numbers are much better now than say a few months ago but there are still huge limitations and vital statistics (death certificates) will most likely give the best numbers, the main issue there is timeliness (months to years).
2
2
u/Kindspiriter Jun 24 '20
"Accurately" is a bit of a nebulous term in epidemiology
This might be a bad sign for the field of epidemiology.
2
u/PHealthy Epidemiology | Disease Dynamics | Novel Surveillance Systems Jun 25 '20
When dealing with inferences and probabilities, accurately can be a moving definition. If you read my full comment you'd see I get into that with the sentinel site surveillance, those sites are funded to report as accurately and completely as possible, from those sites we estimate the true burden for the rest of country. It's a prediction that can be tested through representative surveying but in the end we'll never really know the true burden. We can and do have confidence in our estimate though.
2
u/Prasiatko Jun 25 '20
One problem we have had in Finland is that the reduction in other fatalities e.g vehicle and pedestrian deaths combined with a well contained virus means net total deaths have actually decreased making it not a good way to measure COVID deaths.
1
-4
4
u/metalski Jun 24 '20
Note that some other illnesses will see higher deaths due to medical resources being redirected to the pandemic and people will not seek treatment to avoid infection.
Of course you'll also see things like flu infections going down due to isolation so there's some significant uncertainty dependent on data I'm not sure how we can gather.