Same-day flu and pertussis vaccines appear safe
Giving influenza and pertussis vaccines on the same day after 20 weeks of pregnancy was not linked to worse pregnancy or newborn outcomes than pertussis vaccination alone.
*Retrospective matched cohort study; Level 2b (OCEBM).

Citation

Sonneveld N, Reekie J, Deng L, O’Grady K-A, Macartney K, Liu B. Coadministered influenza- and pertussis-containing vaccines in pregnant women. JAMA Network Open. 2026;9(4):e267551. doi:10.1001/jamanetworkopen.2026.7551

Background

Safety worries can reduce vaccine acceptance during pregnancy. Same-day vaccination could improve coverage, but stronger real-world safety data are needed.

Patients

Singleton pregnancies in New South Wales, Australia, with estimated last menstrual period from January 1, 2021, to March 12, 2022. Exclusions included multiple gestations, more than one influenza or pertussis dose during pregnancy, and conflicting vaccination records across data sources.

Intervention

Same-day influenza and pertussis vaccination at 20 weeks’ pregnancy or later.

Control

Pertussis vaccination alone at a similar date, pregnancy week, and maternal age (1:1 matched).

Outcome

Primary: preterm birth, stillbirth, small size for pregnancy age, low birthweight. Secondary: major bleeding before/after birth, pregnancy-related high blood pressure, early rupture of membranes, preterm labor, and low 5-minute Apgar score.

Follow-up Period

From vaccination to delivery (preterm outcomes censored at 37 weeks).

Results

13,918 matched pregnancies were analyzed (6,959 per group; mean maternal age at delivery 31.7 years). Same-day vaccination was not associated with higher rates of adverse outcomes.

  • Preterm birth: 3.8% vs 4.4%; adjusted relative rate 0.83 (95% interval, 0.66 to 1.05).
  • Small size for pregnancy age (term births only): 8.8% vs 9.9%; adjusted relative odds 0.87 (0.74 to 1.04).
  • Low birthweight (term births only): 1.7% vs 1.6%; adjusted relative odds 0.94 (0.66 to 1.35).
  • Stillbirth was rare (17 total), limiting analysis.
  • No clear differences in secondary outcomes; sensitivity analyses were consistent overall.

Limitations

Observational design leaves room for unmeasured differences between groups (for example, health-seeking behaviors). Many pregnancies were excluded due to inconsistent vaccination records, which may limit generalizability. Some hospital data were missing for selected outcomes.

Funding

Australian government and New South Wales health agencies; national research grants.

Clinical Application

Clinicians can recommend same-day influenza and pertussis vaccination from 20 weeks’ pregnancy to improve uptake without evidence of increased serious pregnancy or newborn harm.