PITTSBURGH — Since the nation’s vaccination efforts began in December, millions have received a full dose of the COVID-19 vaccine, but as the original virus and its variants spread, health experts say there are concerns about another group — those who received the first dose of two-dose courses like Pfizer and Moderna but not the second.
Doctors say they hope continued education and understanding will help bridge the gap.
The latest concern centers on the delta variant of the virus, which has spread from India to England and, now, the United States. The highly contagious variant recently became dominant in the U.S., accounting for 51.7% of new cases, according to the Centers for Disease Control and Prevention.
“Part of the reason we want people to have the full vaccine series is we need protection against these variants. And delta won’t be the last variant,” Dr. Richard Zimmerman, a vaccine policy expert at the University of Pittsburgh, said. Zimmerman also practices family medicine with an emphasis on the influenza vaccine for UPMC.
As of July 7, Pennsylvania provided the first doses of the vaccine to 63.3% of its population, according to the CDC. That means the state ranks ninth in terms of percentage of the population that is at least partially covered. The CDC also noted that by July 7, 60.8% of Pennsylvanians ages 18 and older were fully vaccinated.
Allegheny County, in terms of individuals who are partially vaccinated, is doing even better.
The county ranks second in the state for the percentage of residents who have received at least one vaccine dose, with 73.5% of people at least partially vaccinated, according to state Department of Health data. The data does not include information about how many individuals received vaccines from clinics in Philadelphia as that county has different reporting requirements and receives its own vaccine allotment from the federal government.
Dr. Amy Crawford-Faucher, vice chair of Family Medicine at Allegheny Health Network, said she wasn’t sure how accurate the data is involving the gap between first and second shots. She mentioned that in May, AHN gave a lot of first doses to college students in Pittsburgh who then traveled back home, potentially out-of-state, before they were eligible to get their second shot.
“They may well have gotten it, but we don’t have access to that data,” Crawford-Faucher said.
Even so, doctors are pushing for people to finish their vaccine courses. They emphasize that a single dose — when two doses are recommended — may not be enough protection for future variants of the vaccine.
Two cases of the delta variant already have been found among Allegheny County residents in samples from April and May, according to Dr. Debra Bogen, the director of the Allegheny County Health Department.
In Britain, Zimmerman said, health care providers increased the time between the first and second vaccine shots and discovered that one dose was only about as third as effective at protecting individuals from the fast-spreading delta variant than a full course.
A new study by a team of French researchers published Thursday found that receiving just one dose of Pfizer or AstraZeneca “barely inhibited” the delta variant. However, receiving both doses created a “neutralizing response” in 95% of individuals against the variant, the study found.
As the number of variants increases, Zimmerman said, “you’re really going to need the two doses to have enough protection.”
There are other worries in terms of health effects of catching the older versions of the virus as well.
“What I tell folks who are leery or don’t feel like they need a second dose is that, you know, yes, you’re probably fairly well protected from getting admitted to the hospital or dying from COVID, and that’s great, that’s a step in the right direction,” Crawford-Faucher said. “But if you’re at any risk of getting COVID still, you could get that long-haul COVID, and that is a very concerning condition affecting millions of people now, and we don’t have a great endpoint or treatment for it. And so I say just finish the job. Get it done.”
During the time between the first and second shots of the Pfizer vaccine, Crawford-Faucher said a person’s immunity increases from only around 20% to about 80% right before their second shot in the third week.
If a person was four weeks out from receiving the first shot, Crawford-Faucher added, immunity would still be around 80%. This means that while 80% of individuals in this situation would have “pretty darn good” immunity, 20% would not.
And “you don’t know which group you’re in,” Crawford-Faucher added.
The CDC said people should get their second dose within the recommended three- or four-week period but can wait up to six weeks if necessary. If an individual decides to wait even longer, the CDC says they do not have to start over in the vaccination process.
However, if people want to finish their course but are worried that they have missed that six-week mark, Zimmerman said that the booster effect of a second shot should still be there.
“As long as a person is immuno-competent, they have not developed cancer or something like that, then the idea of the second dose boosting from the first will be intact, even if it’s a year later,” Zimmerman said. “So you don’t have to restart the series; you can just pick up where you left off. But, there may be a window of inadequate protection between the first and second dose, and so that window is the concern.”
Crawford-Faucher added that although health care providers don’t really know what will happen if individuals get their second shot six months after their first, she suspects that the booster effect will hold.
“I’ve been vaccinated. My wife, my mother, all four of my children — and they’re adult children — but our entire family is vaccinated, and we believe that’s the safest thing for ourselves,” Zimmerman said. “The safest thing for our friends, our community, is for us to be part of that vaccine and to help protect others.”
———
