Mixing coronavirus vaccines linked to more side effects: Study
A range of symptoms including headache and chills were reportedly more prevalent following a mixed regimen.
The first data from the U.K.’s trial on mixing coronavirus vaccines has shown a higher rate of side effects such as headache and chills than standard regimens.
Participants reported more symptoms from the Oxford/AstraZeneca jab followed by the BioNTech/Pfizer jab, and vice versa, than from standard schedules, according to early data from the Com-COV study published in The Lancet late Wednesday. The initial findings looked at the side effects after two doses were administered four weeks apart.
For example, around 10 percent of people reported chills after the second dose of AstraZeneca in the standard schedule. If they had received Pfizer after AstraZeneca, that figure increased to around 40 percent, said Matthew Snape, lead investigator of the Oxford University trial.
The standard Pfizer schedule reported around 25 percent have chills after the second dose, while over 45 percent reported chills with AstraZeneca after Pfizer. A similar trend is seen across a range of symptoms — including fatigue, feverishness, headache, joint pain, malaise and muscle ache.
Snape told journalists this was a “really intriguing finding, and not something necessarily we were expecting to see such a consistency on.”
He said that most of these effects were mild and short-lived. But the study also showed an increase in moderate symptoms with the combinations.
The data also confirmed what was suspected from existing schedules: There are more reported side effects after the first dose of AstraZeneca than the second, and more after the second dose of Pfizer than the first.
The study is also testing side effects and the immune response with a 12-week interval, and is now adding in randomized prophylactic paracetamol versus paracetamol when needed, to advise on reducing these symptoms, said Snape. Data on the immune response from these combinations is expected in June.
The trial — which has expanded to include vaccines from Moderna and Novavax — has lots of interest globally, Snape said, noting the team has shared its data with national immunization technical advisory groups in Scandinavia, Northern Europe and Canada.
Some countries, including France and Germany, are already administering an mRNA vaccine to young adults who have had a first dose with the Oxford/AstraZeneca jab, over blood clots concerns.