Influenza Prophylaxis for Family Members
Annual influenza vaccination is the primary recommendation for all family members 6 months and older, with antiviral chemoprophylaxis reserved for specific high-risk scenarios when vaccination alone is insufficient. 1
Primary Strategy: Annual Vaccination
All household contacts and caregivers of children should receive annual influenza vaccination, particularly when caring for: 1
- Children younger than 24 months (especially infants under 6 months who cannot be vaccinated themselves) 1
- Children with high-risk medical conditions 1
- Any unimmunized children at high risk 1
The pediatric office can serve as an alternate venue for vaccinating parents and adult caregivers, facilitating family-wide protection through a "cocooning" strategy. 1 This approach is particularly critical for protecting infants younger than 6 months who are too young to receive influenza vaccine themselves. 1
When to Add Antiviral Chemoprophylaxis
Antiviral chemoprophylaxis (oseltamivir or zanamivir) is recommended for unimmunized family members in these specific situations: 1
Postexposure Prophylaxis (Must Start Within 48 Hours)
- Family members at high risk of complications who have been exposed to a household member with confirmed influenza 1
- Unimmunized family members with ongoing close exposure to unimmunized children at high risk or infants/toddlers younger than 24 months 1
Pre-Exposure Prophylaxis
- During the 2-week period after vaccination for high-risk family members, before optimal immunity develops 1
- When circulating influenza strains are mismatched with vaccine strains, based on CDC surveillance data 1
- When vaccine is contraindicated in a family member who has close contact with high-risk children 1
Dosing for Chemoprophylaxis
Randomized placebo-controlled studies demonstrated efficacy of oseltamivir and zanamivir for household prophylaxis after a family member developed laboratory-confirmed influenza. 1
Household setting: 10 days of daily prophylaxis 2 Community outbreak: Up to 28 days of daily prophylaxis 2
Prophylaxis should be initiated within 48 hours of exposure for optimal effectiveness. 1
Critical Caveats
Chemoprophylaxis is NOT a substitute for vaccination. 1 Family members receiving antiviral prophylaxis remain susceptible to influenza once medication is discontinued, and should still receive vaccination even after influenza has begun circulating in the community. 1
Oseltamivir resistance can emerge during postexposure prophylaxis, requiring awareness of this possibility. 1
Zanamivir is contraindicated in individuals with underlying airways disease (asthma, COPD) due to risk of serious bronchospasm. 2
Decisions about chemoprophylaxis must account for the exposed person's risk of complications, vaccination status, type and duration of contact, and local public health guidance. 1
Practical Implementation
Pediatricians should evaluate household members during well-child visits to identify unvaccinated family members and facilitate their immunization. 1 When a child develops influenza, immediately assess whether household contacts meet criteria for postexposure prophylaxis, particularly focusing on high-risk individuals and caregivers of infants under 6 months. 1
Pregnant women should be prioritized for vaccination to provide passive immunity to newborns through maternally-derived antibodies, protecting infants during their first months of life before they can be vaccinated. 3