The troublesome U.S. booster gap

The Washington Post
President Joe Biden receives his second coronavirus booster shot in the South Court Auditorium at the White House on March 30. Washington Post photo by Demetrius Freeman

Eight months ago, President Joe Biden unveiled a plan to deliver coronavirus booster shots to all vaccinated American adults.

But today, booster shots loom as a significant shortcoming in the federal government’s coronavirus response – with no easy answers for why it has happened or what to do about it.

While Biden aimed for all vaccinated adults to get a booster, only about half have gotten one thus far. The number of Americans overall who have received a booster has essentially flatlined at 30% – about half the rate in some other Western countries – with new vaccinations overall hitting new post-2020 lows.

While booster uptake surged in countries including Germany, Canada and the United Kingdom as the omicron variant emerged, that surge never reached the United States – and still hasn’t.

Certainly, the reasons for this are varied.

One is that we have lower vaccination rates, in general, than many of these countries – meaning the population eligible for boosters is smaller. Even so, our booster uptake has been significantly smaller as a share of eligible people.

A big factor is how partisan vaccines have become in the United States. Republicans form a very disproportionate share of the unvaccinated, and vaccinated Republicans are also significantly less likely to get boosted than vaccinated Democrats. That means the booster campaign has effectively exacerbated the partisan gap in protection from the coronavirus. It also means that most of the unboosted are unlikely to listen to the Biden administration.

But partisanship doesn’t explain it all. These are people who were willing to get two shots and, for whatever reason, haven’t been convinced to get a third.

Another potential reason is the confusing rollout. When Biden made the announcement in August, health officials made clear they weren’t quite ready for it. The boosters wouldn’t be authorized for all adults until three months later – two months after the Sept. 20 date the White House had pegged for the launch of its campaign. Some health advisers grumbled that Biden’s announcement put pressure on apolitical health advisers, something that happened repeatedly in the Trump administration. And what followed was a series of mixed and muddled messages about who was eligible to get boosters, who was advised to get them and when.

The Atlantic last week included this among a series of reasons for slower booster uptake. Others include the original belief that vaccination was a one-time deal, and the high number of breakthrough infections that occurred during omicron – which some people, especially in conservative media, cited as a sign the vaccines didn’t really work. (In fact, though infection rates among vaccinated people did rise, unvaccinated people were many times more likely to wind up in the hospital or dead.)

What’s troubling is that there’s little sign that uptake will increase any time soon. In fact, there are signs that opposition to boosters is actually increasing and hardening among the vaccinated.

The Kaiser Family Foundation in January found that over 40% of vaccinated Americans said they either definitely wouldn’t get boosted or that they would only do so if required. A survey the following month showed that number rising to 47%. Some of the growth of that share is likely because some in the original survey group got boosted – removing them from the universe of responses – but the percentage of vaccinated-but-unboosted Americans didn’t increase by that much over that period.

Another recent poll from Monmouth University also speaks to this. Back in September, when Biden’s booster campaign was due to launch, two-thirds of American adults said they were at least “somewhat likely” to get boosted when the boosters became available to them. By late March, though, the same poll showed only 48% said they had been boosted, and the percentage who were either boosted or at least “somewhat likely” to get boosted had dropped from two-thirds to 6 in 10.

The same poll in September and November showed about one-quarter of Americans said they were “not at all likely” to get boosted, but that number has since risen to 3 in 10 in January and is now 33%.

That suggests that many of the people in the “somewhat likely” or “not too likely” categories have since moved away from the boosters, rather than toward them; people who said they were open to being convinced haven’t been. And whatever the reasons for this trend, the resulting booster uptake is far different than what we’ve seen in other, comparable countries.

Thus far, the booster gap doesn’t appear to have resulted in worse outcomes in the United States, relative to other countries with higher booster uptake. Data show the protection gap between unvaccinated people and vaccinated-but-unboosted people is the really significant one.

But federal government data also show a significant gap in outcomes between the boosted and unboosted, as we wrote back in January:

To be clear, the death rates for both remain extremely low. The weekly death rate over the final three months of 2021 was a little more than 1 per million for boosted people, and about 6 per million for vaccinated-but-unboosted people. Those compare to the 78 per million weekly rate we see from unvaccinated people. But we’ve also seen that protection from the vaccines wanes over time – more so for protection from infection, but also somewhat for protection from hospitalization and death – which is a big part of the reason for the booster push.

In other words, it has been very good to be vaccinated, and significantly better to be boosted. But given that vaccine immunity wanes over time and that new variants could be unpredictable and more deadly, our lagging booster rate creates all kinds of potential consequences down the road.