This is where the
Diamond Princess data provides important insight. Of the 3,711 people on board, at least 705 have tested positive for the virus (which, considering the confines, conditions, and how contagious this virus appears to be, is surprisingly low). Of those, more than half are asymptomatic, while very few asymptomatic people were detected in China.
This alone suggests a halving of the virus's true fatality rate.
On the
Diamond Princess, six deaths have occurred among the passengers,
constituting a case fatality rate of 0.85 percent. Unlike the data from China and elsewhere, where sorting out why a patient died is extremely difficult, we can assume that these are excess fatalities — they wouldn't have occurred but for SARS-CoV-2.
The most important insight is that all six fatalities occurred in patients who are more than 70 years old. Not a single Diamond Princess patient under age 70 has died. If the numbers from reports out of China had held, the expected number of deaths in those under 70 should have been around four.
The data from the
Diamond Princess suggest an eightfold lower mortality amongst patients older than 70 and threefold lower mortality in patients over 80 compared to what was reported in China initially. But even those numbers, 1.1 percent and 4.9 percent respectively, are concerning. But there's another thing that's worth remembering: These patients were likely exposed repeatedly to concentrated viral loads (which can cause worse illness). Some treatments were delayed. So even the lower CFR found on the
Diamond Princess could have been even lower, with proper protocols. It's also worth noting that while cruise passengers can be assumed to be healthy enough to travel, they actually tend to reflect the general population, and many patients with chronic illnesses go on cruises. So, the numbers from this ship may be reasonable estimates.
This all suggests that COVID-19 is a relatively benign disease for most young people, and a potentially devastating one for the old and chronically ill, albeit not nearly as risky as reported. Given the low mortality rate among younger patients with coronavirus — zero in children 10 or younger among hundreds of cases in China, and 0.2-0.4 percent in most healthy nongeriatric adults (and this is still before accounting for what is likely to be a high number of undetected asymptomatic cases) —
we need to divert our focus away from worrying about preventing systemic spread among healthy people — which is likely either inevitable, or out of our control — and commit most if not all of our resources toward protecting those truly at risk of developing critical illness and even death: everyone over 70, and people who are already at higher risk from this kind of virus.
