One of the main reasons that this virus (as well as many others) is especially dangerous to older individuals is that our immune system becomes less effective as we age. This process is called immunosenescence, and it basically means that older people are more susceptible to anything that the immune system would normally defend against - including infections, as well as cancer. Unfortunately, this still applies even to older people who are otherwise in good health.

So, while a healthy senior is probably not in as much danger as another elderly person who is also, for example, diabetic, or has a heart problem, you are still in more danger than you would have been at age 35 or 45.

We can see this by looking at lethality by age group in COVID-19 patients in the US. According to the Centers for Disease Control and Prevention, through November 28th, persons aged ≥85 accounted for the highest proportion of COVID-19 deaths at about 30 percent, followed by persons aged 75–84 years at about 27 percent, and persons aged 65-74 years at 21 percent. At the other end of the spectrum, people younger than 25 years of age account for less than one percent of COVID-19 deaths.

Updated 7 December 2020