Covid versus Flu

In a recent post I acknowledged that younger people face less risk from coronavirus than older people do from the flu. That was cavalier of me. It’s true enough as of now. The question is whether the epidemic is approaching the end of its first wave, or if it’s still just beginning.

The basic statistical comparisons:

Mortality rate: flu = 0.1%, covid = 1%. For those who get infected, covid is ten times as lethal as flu.

Prevalence: Flu infects around 30 million Americans per year, or 9% of the population. So far covid has infected maybe 10 million Americans, or 3% of the population. As of now you’re 3 times as likely to get flu as covid.

Death rate = mortality x prevalence. For flu = .001 x .09 = 90 per million population. For covid, .1 x .03 = 300 per million. As of now covid has been killing people at more than 3 times the rate as the flu.

Body count: flu = 330M x 90 = 30 thousand; covid = 330M x 300 = 100 thousand.

So, if the corona epidemic were to stop dead in its tracks today, it would have killed more than 3 times as many people as does the flu during a typical season. The flu does in fact stop dead every year. The flu is half as contagious as covid, and a substantial percentage of people take the flu vaccine, reducing the number of potential hosts. After a few months the flu epidemic plays itself out. Covid is different. Instead of a biological vaccine, societies rely on behavioral means of slowing contagion — social distancing, quarantine, etc. If stringent levels of containment were to persist, the current wave of the epidemic might play itself out after having infected 5 percent of the US populace and having killed around 150 thousand:  5 times as deadly as the typical flu season.

If prevention lapses and the viral contagion regains momentum, it could continue spreading until 80 percent of the population has been infected and 2.6 million have died. Under the “herd immunity” scenario, covid is nearly a hundred times as deadly as the flu.

About 20% of covid deaths occur among people younger than 65: that’s 20K of the 100K deaths to date. If the epidemic persists until herd immunity is achieved, then 20% of the two and a half million Americans who die will be under 65.

That’s 500 thousand people under age 65 dead of corona over the next year as the epidemic plays itself out in this country. For all of 2018, 700 thousand people under age 65 died from all causes combined.