Will the definition of “fully vaccinated” have to change again? For the last several months, the CDC has urged all Americans to not just get the original vaccination regimen (two mRNA shots or one Johnson & Johnson inoculation) but also a booster shot in order to resist serious or severe acute infections of COVID-19. Now, however, a New York Times analysis of new CDC data shows that boosters may only make a difference in older and/or sicker Americans:

The figures confirm that booster doses are most beneficial to older adults, as the C.D.C. has previously reported. But the new numbers for younger Americans were less compelling. In those age groups, vaccination itself — two doses of the Moderna or Pfizer-BioNTech vaccines, or one dose of the Johnson & Johnson vaccine — decreased the risk of hospitalization and death so sharply that a booster shot did not seem to add much benefit.

The new data supports boosters, but not universally. The impact of a booster dramatically differed based on age and pre-existing comorbidities. Seniors got a massive benefit from vaccination and even more from boosters:

As of Dec. 25, the rate of hospitalization among unvaccinated adults older than age 65 was 246 per 100,000 people. That rate dropped to 27.4 per 100,000 among people who were vaccinated without a booster dose, and to 4.9 among those who were vaccinated and received a booster.

This in itself should get some focus among older Americans. The COVID-19 hospitalization rate goes up almost ten times for unvaccinated seniors. It’s fifty times higher for unvaccinated versus vaccinated-and-boosted. Boosted seniors are five times less likely to be hospitalized with COVID-19 than those who got just the original regimen. Even if a significant amount of these hospitalizations were correlative rather than causative, these differences are clearly not statistical anomalies.

The data on deaths is just as dramatic for seniors:

There were roughly 44 deaths per 100,000 unvaccinated adults 65 and older. Vaccinations dropped that number to about 3.6 deaths per 100,000, one-twelfth as much. Booster shots reduced the rate further, to about 0.5 deaths per 100,000, a figure 90 times as small.

Among adults between 50 and 64 years of age, however, the gaps narrow substantially, although the benefits of original-regimen vaccination are still substantial:

Among adults 50 to 64, 73 unvaccinated adults per 100,000 were hospitalized, compared with nine per 100,000 among those who were vaccinated and just two per 100,000 among those who had also received a booster shot.

Boosters made less of a difference in the number of Covid deaths in this age group. Vaccinations decreased the rate to 0.4 deaths per 100,000 from 8.26 per 100,000. With boosters, that number fell to 0.1 deaths per 100,000 people.

Bear in mind that this group is much less likely than seniors to develop severe consequences from COVID-19 in the first place. The starting position in unvaccinated seniors for hospitalizations, as noted above, is 246/100K and deaths 44/100K. The 50-64YO contingent is three times less likely to be hospitalized even without vaccinations, and almost six times less likely to die, in terms of overall population risk. That likely plays into the lessening of impact from boosters, although a drop from 0.4 deaths per 100K to 0.1 deaths per 100K still counts for a significant number of deaths in large populations.

With boosters in both groups, the death rate from COVID-19 resembles the flu, a non-benign respiratory disease that we nevertheless handle without extraordinary impositions on commerce and community life. That data mainly comes from the Delta wave, too — a more pernicious variant than Omicron, which itself produces less severe results. That’s very good news, and a great reason for those 50 and over to get vaccinated, boosted, and back to normal life.

What about younger Americans? The CDC oddly didn’t provide numbers for the largest contingent of adults, and the NYT’s Apoorva Mandavilli suspects that a relative lack of actual cases makes it impossible to track. That’s a reasonable assumption, given the Delta figures on hospitalizations and deaths even without booster shots:

The risk of Covid death among Americans ages 18 to 49 was low. The rate was about 0.9 per 100,000 people among the unvaccinated, and plummeted to 0.03 among people who were vaccinated. With the addition of a booster, deaths were too low to measure.

Again, this demonstrates the benefit of vaccinations. At a death rate of 0.9/100K, unvaccinated adults below 50 are at far less risk for death than those above. The death rate is actually a bit below the 2019-19 death rate for flu in the same age group (1.2/100K). Vaccination, however, cuts the death risk thirty times. Why not vaccinate, other than specific and serious contraindications?

By the way, this under-50 demographic does not have a homogenous risk profile to COVID-19. The CDC’s latest data on risks by age group uses the basic risk profile of 18-29YOs as a reference group and then expresses risk in those units. People 30-39 years of age are twice as likely as the reference group to be hospitalized and four times as likely to die. For those between 40-49 years of age, hospitalization risk is also twice that of the reference group, but the death risk is ten times that of 18-29YOs. Presumably the CDC’s data on boosters lumps these groups together because they have a homogenous response in terms of risk profile from having been boosted, but those in the upper half should understand that their underlying risk is higher than the mean assumed in this reporting.

This calls into question, again, the public-policy response on what constitutes full vaccination. Full protection, or at least as full as it can get, clearly means boosters for those above 50 and those with immune-response issues and other comorbidities. Insisting on boosters for younger and otherwise healthy adults looks like a waste of time at this point, especially as the Omicron wave recedes. Politicians and bureaucrats have seized on boosters because it’s an objective metric, but it may not measure much for most American adults. It certainly doesn’t measure impediments to community transmission as we have discovered in both the Delta and Omicron waves; at best, it measures strength against serious and/or severe cases of COVID-19 that relate to health-care utilization, but mainly relates to the expected risk and outcomes from individual choices on initial  vaccinations as well as boosters.

And let’s not forget that this doesn’t account from the widespread exposure of Omicron, Delta, and Alpha in our population already. This is no longer a novel coronavirus; the population now has a substantial immune response to it. It may not be complete, and it may not have touched every single human in the US yet. However, it has penetrated far enough — especially with its trademark asymptomatic transmission in all variants — that our assumptions should now be based on endemicity rather than emergency containment to protect a population with no immune response at all.

In the end, attempts to apply one-size-fits-all categories and restrictions are pointless. This is not a one-size-fits-all disease, and it never has been. The risks are far greater for older people, and will remain so like most if not every respiratory disease known to man. The spread of the variants now is known to be untethered to vaccinations, probably all along but especially with Omicron and Delta, so there is no real public policy justification for vaccination-related restrictions — especially as it relates to boosters. Those at higher risk will need to take precautions just as we do with the flu, and everyone else should get back to normal life. If people choose not to get vaccinated or boosted, that’s a risk they can choose and bear that risk burden themselves rather than transfer it to everyone else.