0400 GMT January 23, 2019
Canadian scientists found there is a low rate of recurring reactions following subsequent vaccinations. They said their findings should help inform doctors and parents about the safety of immunizations, UPI reported.
"Most patients with a history of mild or moderate adverse events following immunization can be safely re-immunized," said study leader Dr. Gaston De Serres, of Laval University in Quebec.
In the US, health care professionals are legally required to report reactions to immunizations. Quebec has a similar reporting system for ‘unusual or severe’ vaccine reactions.
For the study, De Serres and colleagues analyzed data on 5,600 patients in this Canadian database from 1998 to 2016. All required additional doses of a vaccine that caused them to have a reaction. The researchers noted the seasonal flu shot was not included in the study since this vaccine changes from year to year.
Follow-up data was available on 1,731 of these patients. Of these, 78 percent, or 1,350 people, received an additional vaccination. In most cases, the patients who received booster shots were younger than two.
The study found that only 16 percent of the patients had another reaction after receiving an additional vaccination. The researchers also found that more than 80 percent of these subsequent reactions were not any more severe than the initial reaction. Patients' gender didn't affect the rate of reactions.