Gap persists between partially and fully vaccinated, but targeted outreach is limited

Oct 4, 2021

Out of the some five million Massachusetts residents who are vaccinated against COVID-19, about a half million have only gotten one dose. This gap hasn’t gotten a lot of attention among public health messages, but some experts say it is concerning.

The CDC reports there’s an approximately 10% gap between Massachusetts residents who are fully vaccinated (68.1%) and those who have gotten one dose of the two-shot Pfizer or Moderna vaccines (77.7%).  

The gap is similar for each age group, though older people have higher rates overall. And the numbers are similar nationally.

Last spring, Texas Governor Gregg Abbot reached out to that gap in his state, saying, “It is important that Texans who received the first dose of the Pfizer or Moderna vaccines go back for the second dose a few weeks later. With both doses, you’re better protected.”

The science says that, at least before the delta variant, one dose of the Pfizer vaccine gives you about 52% protection against the worst effects of COVID-19, compared to more than 90% after the second dose.

One might expect those who have skipped the second dose are at least open to vaccination, and therefore good targets for public health campaigns.

But Armando Paez, head of infectious disease at Baystate Medical Center in Springfield, said there’s another way to think about it.

“The more that you have at least one dose will have an effect in the community in controlling the pandemic,” he said.

Paez would rather have a large number of people with one dose, than a smaller number with two. That way, the community’s overall immunity could be, on average, higher. That’s why his staff focuses on the completely unvaccinated.

“It’s basically [more] bang for your buck,” he said. “If we had bandwidth to to tackle both, of course, that's the ideal situation.” 

Students at Central High School in Springfield, Massachusetts, take part in a COVID-19 vaccination campaign.
Credit Karen Brown / NEPM

Bandwidth seems to be the operative word for a lot of health officials.

Springfield's health commissioner, Helen Caulton-Harris, recently attended a vaccine event at Central High School.

“It is our goal to have two doses and we will make follow up telephone calls to those individuals that we vaccinated through the Department of Health and Human Services,” Caulton-Harris said. “However, there are vaccinations happening across the city, and we can't possibly target all of those because we just don't have the capacity.”

At the same event, several students were encouraging their classmates to start the vaccination regime. Joshua Valle said he knows people who have only gotten one dose.

“My only logical reasoning would be that their time … some people have things to do and they can't get to it,” Valle said. “But other than that, I don't really see another reason why they wouldn't, you know?”

Estevan Garcia, chief medical officer at Cooley Dickinson Hospital in Northampton, said his staff doesn’t focus on the partially vaccinated — in part because they’re hard to track. Just because someone didn’t get a second dose at Cooley Dickinson doesn’t mean they didn’t get one at a pharmacy or somewhere else.

“I'm not sure how accurate all of the information is based on the ability to get vaccines at different sites,” he said.

But from a public health standpoint, Garcia thinks it’s worth trying to understand why people only get one dose.

“[Figuring out] what [are] the barriers to that second vaccine and then really doing outreach. Is it equally distributed in every community? Or are there communities where we could be focusing our attention?” he said. “I think we should be doing that at the state level, for sure.” 

A state public health spokesperson discounted the problem of partially vaccinated people. She said the numbers fluctuate constantly and some of the gap can be explained by people still in the three or four week waiting period between doses. 

State data show the waiting period could explain about 100,000 of the approximately 500,000 people who are partially vaccinated. The rest are either late for — or are skipping – their second dose. 

Going forward, the question of partial vaccination is likely to get more complicated. With the arrival of booster shots, the very definition of fully vaccinated for some groups goes from two shots to three.