Influenza

Pregnancy: Safe and recommended in all trimesters.

Inactivated influenza vaccines (IIV) are safe and actively recommended during all trimesters of pregnancy (WHO, CDC/ACIP).

• Pregnant women are at increased risk of severe influenza and influenza-related hospitalization.

• Maternal vaccination provides passive antibody transfer, protecting the newborn for the first 2–6 months of life.

• Live attenuated intranasal vaccine (LAIV/FluMist) is contraindicated in pregnancy.

• Recombinant (Flublok) and cell-culture vaccines are also safe during pregnancy.

Breastfeeding: Safe — no restrictions.

All inactivated influenza vaccines are safe during breastfeeding. LAIV (live intranasal) is also considered safe during breastfeeding by CDC. No modification to breastfeeding schedule required.

Pediatric use:

• Licensed from 6 months of age (inactivated).

• Children 6 months–8 years receiving influenza vaccine for the first time: 2 doses ≥4 weeks apart.

• LAIV (FluMist intranasal): approved from 2 years to 49 years. Contraindicated in children <2 years and those receiving aspirin/salicylate therapy.

• Dose: 0.5 mL IM (all ages ≥6 months). LAIV: 0.2 mL intranasal (0.1 mL per nostril).

• Annual vaccination recommended — ideally before influenza season onset.

Geriatric use: Enhanced formulations recommended for ≥65 years.

• Adults ≥65 years are at highest risk of influenza-related hospitalization and death.

• Preferred formulations for ≥65 years:

  • High-dose quadrivalent (Fluzone HD): 4× antigen content, 24% more effective than standard-dose.
  • Adjuvanted (Fluad): MF59 adjuvant boosts immune response.
  • Recombinant (Flublok HD): 3× antigen content.

• If preferred formulations are unavailable, standard-dose vaccine is still strongly recommended.

• Annual vaccination is essential (influenza strains change yearly).