Healthy people as young as 45 at greater risk from Covid-19 than people deemed “at increased risk” by the CDC

This is a guest post by Michael Otsuka, Professor of Philosophy at the London School of Economics

A study just published in Nature reveals the following: even for someone with no underlying health conditions, the increased risk associated with being 45 years of age, rather than 30, is greater than the increased risk associated with various health conditions the CDC deems sufficient to render a person “of any age” at “increased risk of severe illness from COVID-19”.

I. Quantifying the risks the CDC recognises

According to the CDC:

The aforementioned study in Nature — which is entitled “OpenSAFELY: factors associated with COVID-19 death in 17 million patients” — quantifies the risks associated with the above health conditions. It indicates that, when one adjusts to control for age, gender, level of income deprivation, and other health conditions, the CDC-listed conditions are associated with increases in one’s risk of death from Covid-19 by the following factors (see righthand column of Table 2 on p. 10):

  • Those who have kidney disease (GFR <30) are at 2.52 times greater risk of death than those without kidney disease
  • Those who have COPD are at 1.63 times greater risk of death than those without respiratory diseases
  • Those who have an organ transplant are at 3.55 times the risk of those without a transplant
  • Those who are obese (BMI of 30 or above) are at 1.05-1.92 times greater risk of death than those who are not obese
  • Those who have chronic heart disease are at 1.17 times greater risk of death than those without heart disease
  • Those who have Asplenia, including sickle cell disease, are at 1.34 times greater risk of death than those without this condition
  • Those who have uncontrolled diabetes are at 1.95 times greater risk of death than those without diabetes

Whatever one’s age — and therefore even if one is as young as 30 years old — having any of the above conditions is sufficient for classification as “at increased risk of severe illness from COVID-19”. The increased risks associated with these conditions range from 1.05 to 3.55 times the risks to those who lack these, as well as any other, health conditions.

Table 2 also indicates the following strikingly dramatically increasing risks associated with advancing age, even among those who are “healthy” insofar as they lack all of the above, as well as any other, health conditions. Compared with a healthy 30 year old:

  • a healthy 45 year old is at 5.00 times greater risk of death
  • a healthy 55 year old is at 16.67 times greater risk of death
  • a healthy 65 year old is at 40.00 times greater risk of death
  • a healthy 75 year old is at 101.33 times greater risk of death

II. Why are those who are older at such increasing risk?

The “OpenSAFELY” study does not address this question. Elsewhere, the hypothesis that Covid-19 involves impairment of the immune system has been offered as an explanation for why increasing age appears to be such a great risk factor:

Many T cells apparently die, and so the body’s reserves are depleted — particularly in those over age 40, in whom the thymus gland, the organ that generates new T cells, has become less efficient.

…The new research may help answer another pressing question: Why is it so rare for a child to get sick from the coronavirus?

Children have highly active thymus glands, the source of new T cells. That may allow them to stay ahead of the virus, making new T cells faster than the virus can destroy them. In older adults, [as mentioned above] the thymus does not function as well.

III. CDC has removed its age 65 threshold for increased Covid risk

In light of findings such as those reported in Nature, it is unsurprising that the CDC has recently “removed the specific age threshold” of 65 which it once affirmed. “CDC now warns that among adults, risk increases steadily as you age, and it’s not just those over the age of 65 who are at increased risk for severe illness” from Covid-19 infection. The CDC also maintains that “Age is an independent risk factor for severe illness, but risk in older adults is also in part related to the increased likelihood that older adults also have underlying medical conditions” (my emphasis added). Sensibly, and in line with the findings of the “OpenSAFELY” study, the CDC now says the following about “Older Adults” under the general heading of “People Who Are at Increased Risk for Severe Illness”:

The data simply does not support an age threshold of 65. As I have shown in Section I above, even those who are 45 years old and healthy are at greater risk than 30 year olds whom the CDC classifies as “at increased risk of severe illness from COVID-19” because of underlying health conditions. If any employer attempts to adhere to the now-discarded age threshold of 65, there will be a glaring lack of consistency and parity in the protections it extends to their workers who are at higher risk.