A new study suggests that the flu vaccine may be less effective than previously thought, which could lead to fewer people receiving the shot.
The study, published online by the Journal of the American Medical Association, found that people who received the flu shots were less likely to have serious side effects compared to those who received a placebo.
It also found that the vaccine had more side effects, including pneumonia, pneumonia-like illness, diarrhea, and vomiting.
The researchers say they found evidence that people taking the flu vaccines were at higher risk for serious side reactions compared to people who did not get the shots.
“We found a statistically significant reduction in influenza-related mortality among people who were vaccinated with flu vaccine, compared to flu vaccine recipients who were not,” said study lead author Michael D. Wojcik, an assistant professor of medicine at the Harvard T.H. Chan School of Public Health.
Wozcik and colleagues examined the data for more than 13,000 people who had received either the flu or the Pneumocystis carinii vaccine, a vaccine that includes antibodies that protect against pneumococcal bacteria.
They looked at how the flu virus mutated over time and how people’s immunity changed over time.
The research team compared the people who got the flu vaccination with the people in the control group.
They also looked at the outcomes of people who took the vaccine for more that three years.
They found that flu vaccine users had higher rates of severe pneumonia, diarrhea and vomiting, and a lower rate of severe respiratory illness.
The flu shot is available for free through most pharmacies.
The Centers for Disease Control and Prevention recommends that people get a flu shot in two doses.
It’s not clear why people who don’t get the vaccine develop side effects like those seen in the study.
The CDC says the flu season ends on Sunday.
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