"Increased Side Effects Like Headache and Fatigue with AZ-Pfizer Mixed Vaccination"

[Image source=Reuters Yonhap News]

[Asia Economy Reporter Cho Hyun-ui] A study has found that mixing AstraZeneca (AZ) and Pfizer COVID-19 vaccines increases the incidence of side effects such as fatigue and headaches.

Bloomberg reported on the 13th (local time) the research results published by the University of Oxford in the international journal The Lancet. All study participants were aged 50 and above.

After administering the first dose with the AZ vaccine and the second dose with the Pfizer vaccine, side effects were observed four weeks later. The study found that initial side effects such as fatigue and headaches were reported more frequently compared to single vaccine administration. All side effects were mild.

In the case of single vaccination, 3% reported severe fatigue after the second dose, whereas 10% experienced such side effects with mixed vaccination. The same was true when the first dose was Pfizer and the second dose was AZ.

Professor Matthew Snape of Oxford University said, "This was an unexpected result," adding, "We will know in a few weeks whether the immune response improvement effect was enhanced." He also stated, "There were no safety issues. Even strong side effects disappeared after a few days," but expressed concern about the increase in side effects.

The research team is also studying mixed vaccinations including Moderna and Novavax vaccines.