Preliminary results of an ongoing study in the United Kingdom suggest alternating the COVID-19 vaccines from AstraZeneca and Pfizer-BioNTech causes mild to moderate symptoms to happen more often. They haven’t yet determined how a combination of shots would affect the immune system’s response compared with using the same vaccine for both the prime and booster shots. Chief investigator Matthew Snape says the results suggest mixed-dose schedules could cause an increase in work absences the day after immunization, which would be useful to consider when planning inoculation of health-care workers.
The study recruited 830 people to evaluate four combinations of vaccination: a first dose of AstraZeneca followed by either a booster shot of the Pfizer vaccine or another dose of AstraZeneca, or the Pfizer vaccine followed by a second shot of either AstraZeneca or Pfizer. Research was expanded last month for a new study with 1,050 volunteers who received either the AstraZeneca or Pfizer vaccine before randomly getting either the same vaccine for their second dose or the Moderna or Novavax vaccine.
The Canadian Press
Photo Credit: AstraZeneca