People can get better immune responses from COVID-19 booster shots if the dose doesn’t match the vaccine received during initial vaccination, according to a lead researcher on the matter from the University Of Maryland School Of Medicine.
Only about 40% of Americans who are fully vaccinated against COVID-19 have received booster shots, Centers for Disease Control and Prevention data indicates.
“If your primary series and the boost were the same, you got a good response. But you could increase that response if you mixed the vaccines,” said Dr. Kirsten E. Lyke, professor of medicine at UMSOM, and the co-chair and the principal investigator for the ongoing study.
“For instance, if you got a Johnson and Johnson and you followed that with either a Pfizer or Moderna, you could really enhance your immune response,” she said.
Lyke also presented data to the U.S. Food and Drug Administration’s expert vaccine panel in October that was pivotal in recommending adults and teens receive COVID-19 booster shots of their choosing starting in fall 2021.
Lyke said the lowest boost of immunity in the ongoing study has occurred among people receiving the Johnson and Johnson boost after initial vaccination with the Johnson and Johnson vaccine.
“While that might, short term, give you protection, if you followed that with one of the mRNAs [Pfizer or Moderna], it’s much more likely that you would have a longer immune response and a much higher antibody response,” she said.
As for which specific mix and match regimen might be most effective, that’s unclear.
“We can definitely quantify, if you want to get the highest neutralizing antibodies, we can definitely say: this appears to have the highest neutralizing antibody,” Lyke said.
“But that doesn’t necessarily mean that if you have a neutralizing antibody of 1,000 — is that really much different than a neutralizing antibody and 700? I don’t think we really know those nuances.”
Lyke said what’s most important is that people get boosted.
“We can show that boosters are your best chance of getting protection against severe disease and death. Will there be breakthrough infections? Yes, there’s going to be breakthroughs, but they will be mild,” Lyke said.
The concept of getting a more vigorous immune response from mix and matching vaccines isn’t new. It also happens, for example, with the Ebola vaccine.
Before the pandemic, Lyke’s primary focus was on malaria and Dengue fever as director of the Center for Vaccine Development and Global Health.
She said it’s been gratifying to step into the COVID arena.
“For instance, malaria — we’ve been working for 50 years, and it’s still a slog to get a viable vaccine. But this has been extremely gratifying. And this isn’t the only study we’ve participated in,” she said.
“I was fortunate to be a co-lead for the original Pfizer vaccine. We vaccinated patient number one in the United States here at the University of Maryland. So we we’ve kind of been in the mix right from the get go.”
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