A British clinical trial found no sign of danger in getting a flu shot and a second dose of a Covid-19 vaccine at the same time. The results are welcome news for strained health care workers as flu season hits. The study supports the advice of U.S. health authorities.
In the study, doctors recruited 679 people between April and June across Britain. At the time, all of the volunteers had received their first dose of a Covid-19 vaccine, either from AstraZeneca or Pfizer-BioNTech, the two vaccines that were first authorized there.
When the volunteers returned for the second dose of their Covid-19 vaccine, the researchers gave half of them a flu shot at the same time, and the other half a placebo.
The researchers then monitored the volunteers for side effects, such as aches and fevers.
“There are no safety concerns raised in this trial,” the authors wrote in their preliminary report, which was posted online on Thursday but has not yet been published in a scientific journal.
In addition to looking at the safety of the vaccines, the researchers also collected blood to measure antibodies to the coronavirus. Some combinations of different vaccine brands led to a slightly lower level of antibodies, and a slightly higher level in other cases. But the researchers did not suspect that any combination of a flu and Covid vaccine would result in a lower effectiveness than each given individually.
The researchers did not speculate about what immune responses people will experience if they get a flu shot at the same time as a third Covid-19 shot, which many people may be doing now that the Biden administration has authorized boosters for large swaths of at-risk Americans.