When comparing the novel coronavirus to the seasonal flu, it seems like the main differences are:
-the seasonal flu is typically around half as infectious (r0 typically 1.4 to 1.6)
-some strains of seasonal flu have a vaccine available; the coronavirus doesn’t yet (although quick progress has apparently been made on the first steps)
But we believe that both seasonal flu and this coronavirus are similarly deadly, largely for the same segment of the population (older/at risk). Have I summarised this correctly?
I don’t think this is a good summary for an important reason: I think the Wuhan Coronavirus is a few orders of magnitude more deadly than a normal seasonal flu. The mortality estimates for the Wuhan Coronavirus are in the single digit percentages, whereas this source tells me that the seasonal flu mortality rate is about 0.014%. [ETA: Sorry, it’s closer to 0.1%, see Greg Colbourn’s comment].
The mortality rate is the proportion of infections that *ultimately* result in death. If we had really good data (we don’t), we could get a better estimate by pitting fatalities against *recoveries*. Since we aren’t tracking recoveries well, If we attempt to compute mortality rates right now (as infections are increasing exponentially), we’re going to badly underestimate the actual mortality rate.
The source you’re looking at considers everyone in the population, even people who don’t get the flu, but the 3% figure for the Wuhan Coronavirus is only considering the people who have been infected.
EDIT: I was wrong, your source is giving the percentage of deaths caused by the flu, not the percentage of the whole population killed by flu each year.
The annual death toll in China is 8.9 million, so 87 deaths would mean 0.00001% are caused by the Wuhan Coronavirus, compared to 0.014% for the seasonal flu. (I don’t think this is a great way to compare, because very few people have been exposed to the Coronavirus so far, but you get the gist.)
The opposite trend occurred for SARS (in the same class as nCoV-2019), which originally had around a 2-5% deaths/cases rate but ended up with >10% once all cases ran their full course.
SARS was very unusual, and serves as a partial counterexample. On the other hand, the “trend” being shown is actually almost entirely a function of the age groups of the people infected—it was far more fatal in the elderly. With that known now, we have a very reasonable understanding of what occurred—which is that because the elderly were infected more often in countries where SARS reached later, and the countries are being aggregated in this graph, the raw estimate behaved very strangely.
When comparing the novel coronavirus to the seasonal flu, it seems like the main differences are:
-the seasonal flu is typically around half as infectious (r0 typically 1.4 to 1.6)
-some strains of seasonal flu have a vaccine available; the coronavirus doesn’t yet (although quick progress has apparently been made on the first steps)
But we believe that both seasonal flu and this coronavirus are similarly deadly, largely for the same segment of the population (older/at risk). Have I summarised this correctly?
I don’t think this is a good summary for an important reason: I think the Wuhan Coronavirus is a few orders of magnitude more deadly than a normal seasonal flu. The mortality estimates for the Wuhan Coronavirus are in the single digit percentages, whereas this source tells me that the seasonal flu mortality rate is about 0.014%. [ETA: Sorry, it’s closer to 0.1%, see Greg Colbourn’s comment].
A better comparison would be to look at death rate for those infected: ~0.1% for seasonal flu.
The mortality rate is the proportion of infections that *ultimately* result in death. If we had really good data (we don’t), we could get a better estimate by pitting fatalities against *recoveries*. Since we aren’t tracking recoveries well, If we attempt to compute mortality rates right now (as infections are increasing exponentially), we’re going to badly underestimate the actual mortality rate.
The source you’re looking at considers everyone in the population, even people who don’t get the flu, but the 3% figure for the Wuhan Coronavirus is only considering the people who have been infected.
EDIT: I was wrong, your source is giving the percentage of deaths caused by the flu, not the percentage of the whole population killed by flu each year.
The annual death toll in China is 8.9 million, so 87 deaths would mean 0.00001% are caused by the Wuhan Coronavirus, compared to 0.014% for the seasonal flu. (I don’t think this is a great way to compare, because very few people have been exposed to the Coronavirus so far, but you get the gist.)
No, the case fatality rate isn’t actually 3%, that’s the rate based on identified cases, and it’s always higher than the true rate.
Estimate of swine flu fatality rate was ~0.5% in July 2009 with 100,000 cases reported. It ended up dropping over an order of magnitude.
The opposite trend occurred for SARS (in the same class as nCoV-2019), which originally had around a 2-5% deaths/cases rate but ended up with >10% once all cases ran their full course.
SARS was very unusual, and serves as a partial counterexample. On the other hand, the “trend” being shown is actually almost entirely a function of the age groups of the people infected—it was far more fatal in the elderly. With that known now, we have a very reasonable understanding of what occurred—which is that because the elderly were infected more often in countries where SARS reached later, and the countries are being aggregated in this graph, the raw estimate behaved very strangely.
I think we were both confused. But based on what Greg Colbourn said, my point still stands, albeit to a weaker extent.