With COVID-19 cases again on the rise and a new strain emerging, those in public health are urging all U.S. adults to get booster shots of the vaccine. But another group — people who never came back for their second dose — is getting less attention.
At least 6.5% of the more than 4 million vaccinated Marylanders haven’t returned for the second shot of the two-dose regimen on the recommended timeline, an analysis of state data by The Baltimore Sun shows. The shots are typically scheduled three or four weeks apart, respectively, for the most widely used vaccines: Pfizer/BioNTech and Moderna.
Experts say a failure to get the next dose not only leaves a person vulnerable to the disease as cases are again on the rise and the newly spreading omicron variant seems less vulnerable to earlier vaccination. Those who become infected also put others around them at risk, perpetuating the pandemic.
“Especially with newer strains out there, we strongly recommend you get a second dose,” said Dr. Gabor Kelen, emergency physician-in-chief for Johns Hopkins Medicine.
“You are not fully protected,” Kelen said. “And this is not only about you.”
Medical and public health experts say there’s little national data about who falls into this group that skipped or missed their second doses. Kelen said he’s been noticing more people who are not fully vaccinated coming into the emergency department, though not necessarily for COVID.
Statewide data shows a small portion of the people who didn’t stay on the vaccine schedule returned within 42 days, the extended window set by the U.S. Centers for Disease Control and Prevention. After that time, Kelen said people should restart the two-dose regimen.
Though much of the marketing and public health outreach has been focused on promoting shots No. 1 or No. 3, state and local health officials say they are aware of this middle group and make an effort to reach them.
“To ensure that all eligible Marylanders complete their primary vaccine series, the Maryland GoVAX call center is reaching out to individuals who have not yet scheduled their second-dose appointment,” said Andy Owen, a spokesman for the Maryland Department of Health. “The call center will place outbound calls and text messages to these patients and offer opportunities to connect to an agent to schedule an appointment at a pharmacy or clinic closest to their residence.”
Local health departments and other providers also have sought to schedule appointments for second doses at the time of the first dose, at the same location if possible.
Officials at the Maryland Department of Health didn’t provide information on who is included in this group or where they live, and there is no detailed analysis from the CDC. The Sun’s analysis, however, shows younger people and minority groups had the lowest rate of return after the recommended three or four weeks for the Pfizer or Moderna vaccine.
At least 1 in 10 Hispanic first-dose recipients missed the deadline to get a second shot, as did at least 9% of recipients who are American Indian or Alaska Native and at least 7.5% of those who are Black. White and Asian recipients are most likely to stay on schedule with at least 5.5% of each group not getting a second shot within the recommended span.
By age, the group most likely to miss their second dose was those 20 to 29, with at least 9.5% not following through. They were followed by those ages 12 to 19 (at least 8%) and ages 30 to 39 (at least 7.5%). From there, follow through generally improves with age.
Nationally, the CDC reported in June that about 11% of people failed to return for a second shot on schedule.
Kelen had no data from Johns Hopkins Hospital, but said his sense was that the people only partially vaccinated at Hopkins were not “anti-vax,” nor did they skip a second shot because of a bad reaction to the first one. They just hadn’t made an effort to get another shot; they forgot or were distracted or felt no urgency to do so, he said.
For most people, it seems “life got in the way,” agreed Dawn O’Neill, vice president of population health at Ascension St. Agnes health system, which helps run vaccination clinics for the Baltimore City Health Department.
Susan Lipton, head of infectious diseases at the Herman & Walter Samuelson Children’s Hospital at Sinai in Baltimore, said she believes some parents delayed a second dose due to fears about myocarditis, inflammation of the heart, after their adolescents received their first doses.
“Vaccinations dropped the second the news came out” about myocarditis cases, she said.
But, she said, fears waned when parents learned that cases were rare and the risks were low because cases were mostly mild. The risk of heart damage is also greater from COVID-19.
The Maryland Hospital Association says that throughout the pandemic, the overwhelming majority of the sickest people in their intensive care units are unvaccinated. That’s true at the University of Maryland Medical Center, said Dr. Greg Schrank, an epidemiologist at the center.
Those with one dose are more likely to come to the hospital for another reason and then officials discover they missed a dose, he said. But he said most information is anecdotal.
“There isn’t robust national data on the hospital rates of partially vaccinated individuals,” Schrank said.
“It is very clear people do develop an antibody response that provides some memory of the virus in those with one dose,” he said. “But as they get further out from that dose, I’m concerned they’d be at higher risk for severe disease than someone who received two doses. And, of course, they can still transmit the virus to others.”
The vaccines’ effectiveness on the new omicron variant is not yet clear.
Pfizer/BioNTech announced Wednesday that a laboratory test found that its two-dose regimen was less effective at preventing omicron, but a booster dose in the form of a third shot increased that efficacy 25-fold. The two companies said they believe the two-dose regimen still prevents severe infection.
But more research is needed to determine how well the vaccines work at preventing severe or mild infections or transmission with the new variant, which is believed to be more infectious.
That uncertainty has prompted more urgent calls for adults to get two shots and a booster at six months (or a booster at two months for the one-shot Johnson & Johnson vaccine).
A single dose of the Pfizer or Moderna vaccines gives some protection against the delta variant, which remains the dominant variant now, said Matt Frieman, associate professor of microbiology and immunology at the University of Maryland School of Medicine and a longtime coronavirus researcher.
And early studies show that people who were infected and got one dose of vaccine have as good an antibody response as someone who got two doses of vaccine. Antibodies are the proteins the body makes to fight off infections. But that finding doesn’t likely hold up over time, he said.
More study is needed, particularly with the new variant, and Frieman encourages everyone, especially those with no vaccinations, to get the shots and boosters in the meantime.
“These vaccines seem to be three-dose vaccines and not two-dose vaccines,” he said, adding that multiple doses are needed for many vaccines. So three shots of COVID vaccine or an annual shot such as the flu vaccine would not be unusual.
“Data suggests booster doses give people longer-term immunity,” he said. “Could it be an annual vaccine? Absolutely. The virus is going to determine future years.”
Baltimore Sun data journalist Steve Earley contributed to this article.
A note on methodology: To gauge second-dose follow-though, The Sun referenced second-dose data from a month ago, enough of a lag, historical data suggests, that virtually all second doses administered by then should be be recorded in the state’s system. Those tallies were compared to the cumulative number of first doses administered 28 days and 42 days prior, corresponding with the recommended second-dose interval for the Moderna vaccine, the longer of the two-dose options, and the period after which public health officials consider a second dose missed. The comparisons reveal the absolute minimum number of missed second doses.