Vaccine study a factor in mix-and-match decision

Results from a UW Medicine COVID-19 vaccine mix-and-match study were reviewed by a Centers for Disease Control and Prevention panel ahead of the group’s decision to authorize mixing and matching of booster shots this week.

“[The] data that we have today shows that it is safe, and also effective at creating a strong immune response,” said Dr. Christine Johnston, associate professor of medicine, Division of Allergy and Infectious Diseases at the UW School of Medicine. “We’re still studying this, but at this point, we’re seeing that this is a safe option.”

Johnston said that each of the approximately 450 study participants received a booster vaccine at least 29 days ago, while some received their additional shot as far out as six months ago. Each possible initial vaccine series has been combined with an alternative booster (either Pfizer, Moderna, or Johnson & Johnson vaccines) and monitored through the study. No adverse effects have been observed, beyond occasional soreness or fatigue associated with the original doses. UW Medicine is one of 10 sites performing the study, which is sponsored by the National Institutes of Health.

While boosters are now authorized for all three types of vaccines available in the United States, there are differences between their doses. Pfizer and Johnson & Johnson boosters are full doses equal to their original series, while the CDC found that the Moderna booster shot provided ample protection as a half-dose compared to its initial series.

Following the CDC’s authorization, booster shots are now available at UW Medicine. Call 844-520-8700 to schedule an appointment, if you qualify according to the details below.

Who qualifies for a COVID-19 booster vaccine of their preference, by initial vaccine series:

Originally received Pfizer or Moderna:

  • Must be six months since your second dose
  • Age 65 or older; or
  • A resident of a long-term care facility; or
  • Age 18-64 with underlying medical conditions or at increased risk for COVID-19 exposure and transmission because of where you work or live (such as healthcare settings, schools, correctional facilities, homeless shelters)

Originally received Johnson & Johnson:

  • Must be two months since your single dose
  • Must be age 18 or older

UW Medicine