BACKGROUND AND PURPOSE:

• There is limited information regarding whether standard-dose, seasonal, trivalent, inactivated influenza vaccination is efficacious for women with HIV
• Nunes et al. (The Lancet, 2020) examined the immunogenicity and safety of using different dosing schedules of inactivated influenza vaccine in pregnant women with HIV

METHODS:

• Double-blind, randomized, controlled trial (RCT)
• Participants
  • Pregnant women with HIV | 18 to 38 years of age
  • Gestational age 12 to 36 weeks
• Intervention
  • Women randomized (1:1:1) in to 3 groups to receive inactivated influenza vaccine with different regimens
    • Single dose
    • Double dose
    • Two single doses 1 month apart
• Study design
  • Participants and study personnel were masked to group allocation
  • Hemagglutination-inhibition antibody responses were measured
    • For all groups in the mothers at enrollment
    • At 1 month after each vaccine dose
    • In the single-dose and double-dose groups within 7 days of birth in the neonates
  • Safety outcomes were assessed mothers and infants until 24 weeks postpartum and analyzed in all participants who received at least one dose of vaccine
• Primary outcomes
  • Immunogenicity
    • Seroconversion rate to each of the vaccine strains in the mothers 1 month after completion of the dosing schedule
  • Safety
    • Frequency of local and systemic reactions

RESULTS:

• 800 pregnant women with HIV were enrolled
  • 266 were in the single-dose group | 265 in the double-dose group | 269 in the two-single-doses group
• In the population analyzed, seroconversion rates were significantly higher in the double-dose group vs single-dose group (p≤0.019)
  • Double-dose group rates ranged from 29% to 65%
  • Single-dose group rates ranged from 18% to 49%
• There was no difference in seroconversion rates in the two-single-doses group vs the single-dose group (p≥0.20)
  • Two-single-doses group rates ranged from 23% to 52%
• Overall, safety outcomes were similar in the three groups
  • Injection-site reactions were increased in double-dose group

CONCLUSION:

• A double-dose of the influenza vaccine conferred higher immunogenicity compared to single-dose regimens in women with HIV
  • Immunogenicity even in the double-dose group remains lower than women without HIV
• The authors conclude that

These findings emphasise the need for continued efforts to find an improved influenza vaccine or vaccination strategy for this population to improve protection of their infants, such as exploring the use of high-dose inactivated influenza vaccine that is currently approved for older adults in pregnant women with HIV

Learn More – Primary Sources:

Immunogenicity and safety of different dosing schedules of trivalent inactivated influenza vaccine in pregnant women with HIV: a randomised controlled trial

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