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Concomitant vaccine-related febrile seizures rare among infants
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The risk for febrile seizures was slightly increased among infants after administration of influenza vaccine when administered with DTaP or pneumococcal vaccine; however, the absolute risk for febrile seizures was low, according to recent research in Pediatrics.
“Our objective was to determine whether other vaccines given concomitantly with [trivalent inactivated influenza vaccine (IIV3)] affected the risk of febrile seizures after vaccination in 2010-2011 or previous influenza seasons,” Jonathan Duffy, MD, MPH, of the CDC’s Immunization Safety Office, and colleagues wrote. “This required examining the febrile seizure risk after the 10 vaccines recommended for all children in the United States.”
The researchers studied 1.9 million vaccination events among children aged 6 to 23 months to determine the risk for febrile seizures up to 1 day after vaccination for all routinely recommended vaccines. The five flu seasons between 2006 and 2011 were evaluated during the study.
Patient data also were analyzed for febrile seizure events after administration of other inactivate and live vaccines, including:
- Prevnar 7 (PCV7, Pfizer);
- Prevnar 13 (PCV13, Pfizer);
- DTaP-containing vaccines;
- H1N1 monovalent inactivated vaccine;
- Haemophilus influenzae type b vaccines;
- Hepatitis A vaccine;
- Hepatitis B vaccine;
- inactivated polio vaccine;
- measles-mumps-rubella vaccine;
- RotaTeq (Merck); and
- varicella vaccine.
Study results showed that concomitant administration of IIV3 with either PCV13 or PCV7 increased the risk for febrile seizures (incidence RR = 3.5; 95% CI, 1.13-10.85). The researchers also found that administration of IIV3 with any DTaP-containing vaccine also increased the risk (IRR = 3.5; 95% CI, 1.52-8.07).
Duffy and colleagues wrote that the absolute risk of febrile seizures was low, with 30 seizures reported for every 100,000 patients vaccinated.
After adjustment, PCV7 was the only vaccine found to have an independent risk for febrile seizures (IRR = 1.98; 95% CI, 1-3.91), according to the study results.
Mark H. Sawyer
“The risk of febrile seizures must be weighed against the benefits of timely vaccination as recommended,” Duffy and colleagues wrote. “The potential benefit of vaccination to prevent febrile seizures over longer periods is less readily apparent than the short-term risk of febrile seizures in the first few days immediately after vaccination. Over the long-term, vaccination might reduce the risk of febrile seizures, though additional study would be needed to quantify this for each type of vaccine.”
In a related editorial, Mark H. Sawyer, MD, FAAP, of the department of pediatrics at the University of California, San Diego and Rady Children’s Hospital, and colleagues wrote that the study by Duffy and colleagues precisely quantifies the risks for febrile seizures and gives pediatricians the information and confidence they need to engage in conversations with parents about the risks and benefits of vaccination.
“Without vaccines to prevent these illnesses, pediatricians would see many more than one case of most of these infections each decade,” Sawyer and colleagues wrote. “In fact, they would see children in their practices with both febrile seizures and life-threatening infections. The risk from these diseases far outweighs the risk from the vaccines. Fortunately, because of the surveillance and research of the Vaccine Safety Datalink, we no longer need to wonder how often adverse events happen after vaccinations.” – by David Costill
Disclosures: Duffy and Sawyer report no relevant financial disclosures. Please see the full study for a list of all other authors’ relevant financial disclosures.
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