Revaccination safe after AEFIs

Among individuals who develop adverse events following immunization (AEFI), revaccination appears to be safe, a recent study has found. Skin testing may also help assess revaccination safety.

Researchers conducted a prospective observational study including 588 participants in whom a total of 627 AEFIs occurred. Most of such side effects (91 percent; n=570) developed in children aged <18 years. Data for the present analysis were retrieved from the Canadian Special Immunization Clinic Network.

Overall, 276 children and 21 adults underwent revaccination during the study. Of these, 10 percent eventually reported recurrence of the AEFI, though none of these cases were deemed serious. AEFI reoccurrence was comparable between children and adults (10 percent vs 14 percent; p=0.55). Influenza and HPV vaccines induced the highest rates of AEFI recurrence, both at 20 percent.

The most common recurrent AEFI was large local reactions, which recurred in 31 percent. This was followed by immediate hypersensitivity, with a recurrence rate of 7 percent.

Of note, among patients with negative skin testing results, 94 percent were recommended for revaccination. Of these, 4 percent developed AEFI recurrences. The resulting negative predictive value (NPV) of allergy skin testing in this case was 96 percent. Meanwhile, in patients with positive skin test results, revaccination was associated with a significantly higher rate of AEFI recurrence than in counterparts with negative results (p<0.001).

“Allergy skin testing has a high NPV for recurrence of allergic-like events, though most patients with positive skin tests also can be safely revaccinated in controlled settings,” the researchers said. “These findings can inform discussions between healthcare providers and patients about the safety of revaccination after an AEFI and support harmonization of management approaches to ensure these patients can be optimally protected against vaccine-preventable diseases.”