Monitoring the safety of the maternal respiratory syncytial virus vaccine

GP Connect Clinical Feature by Dr. Kaija Strautins^a, Grace Pettigrew^a, Dr. Lauren Bloomfield^a, Dr. Dale Carcione^a, Prof Paul Effler^a

The WA Department of Health (WA Health) is monitoring the safety of Abrysvo for adverse events following immunisation (AEFI) and newborn outcomes as part of the 2025 WA Respiratory Syncytial Virus (RSV) Infant and Maternal Immunisation Program.

Key points:

• Abrysvo is an RSV maternal vaccination available for pregnant women under the National Immunisation Program (NIP).
• In WA, one AEFI report of anaphylaxis following Abrysvo has been reported and received clinical follow-up.
• As at 30 May 2025, 28.7 per cent of people (51/178) reported a common and expected AEFI following Abrysvo via the SmartVax survey.
• Two incorrect administrations of RSV immunisation products have been reported.

What has been published on the safety of Abrysvo?

• The Maternal Immunisation Study for Safety and Efficacy (MATISSE) vaccine trial recently reported¹ safety follow up of 3,000 maternal RSV vaccinations:
  • no maternal deaths or stillbirths were assessed as related to vaccination
  • no higher frequency of low birth weight, premature birth or developmental delays, compared to placebo control.
• In 2024, a US real-world study of over 1,000 patients who received a maternal RSV vaccine² reported:
  • no higher frequency of preterm birth, low birth weight or stillbirth
  • no higher frequency of NICU admission, jaundice, hypoglycaemia or sepsis
  • increased risk of overall hypertensive disorders of pregnancy but not pre-eclampsia or eclampsia.
• In 2024, a meta-analysis of six randomised clinical trials³ found no statistical difference for adverse events between women receiving RSV vaccine compared to controls.

How is WA Health monitoring the safety of Abrysvo?

Adverse events following Abrysvo vaccination are monitored via:

1. Reports of reactions to Western Australian Vaccine Safety Surveillance System (WAVSS) by providers or members of the public.
2. Reports of reactions to the Therapeutic Goods Administration by providers or members of the public which are shared with WAVSS.
3. At participating GP clinics and Aboriginal Medical Services, SmartVax surveys are sent three days post-immunisation via SMS, asking recipients if they had a reaction and specific symptoms.
4. Data linkage to identify presentations to emergency departments or hospital admissions up to 60 days after Abrysvo vaccination for specific diagnoses including anaphylaxis, allergic reactions, Guillain Barre Syndrome, cardiac abnormalities, pre-eclampsia, eclampsia, hypertension, pre-term birth and foetal death.
5. Rapid cycle analysis to identify any increase in all-cause presentations to emergency departments up to 21 days post-Abrysvo vaccination.
6. Expert Clinical Review Group meetings every two months to assess referred reports of severe, significant and unusual adverse events following immunisation.

What adverse events following Abrysvo have been reported in WA?

As at 30 May 2025, over 6,500 doses of Abrysvo have been administered in WA.

• 3% of people (127/178) reported no reaction following Abrysvo vaccination via the SmartVax survey.
• For the 28.7% of people who did report a reaction after Abrysvo, 32.3% reported a local reaction, 26.2% systemic aches and pains, 24.6% fatigue, 7.7% chills, 5.4% gastrointestinal symptoms and 3.8% fever.
• SAFEVAC (WAVSS) has received six reports following Abrysvo vaccination:
  • one report of confirmed anaphylaxis (resolved)
  • one report of nausea and feeling faint (resolved)
  • one report of minor site reaction and myalgia (resolved)
  • one report of Arexvy incorrectly administered to a pregnant woman
  • one report of Abrysvo incorrectly administered to a child
  • one report of suspected shoulder injury related to vaccine administration.
• No safety risks have been identified via rapid cycle analysis.

Points to take away:

• Report adverse events following immunisation to SAFEVAC (WAVSS).
• Confirm the correct RSV immunisation product prior to administration:
  • Abrysvo for pregnant women.
  • Beyfortus for eligible infants.
  • Arexvy for older adults.
• Keep Abrysvo, Beyfortus and Arexvy separate in clinic fridges to avoid vaccine administration errors.

Resources:

• WA Health:
  • 2025 WA Respiratory Syncytial Virus (RSV) Infant and Maternal Immunisation Program (including provider fact sheet)
  • RSV immunisation decision aids (flowcharts) for state-wide and Kimberley or Pilbara regions
• The Australian Immunisation Handbook – Respiratory syncytial virus (RSV)
• SmartVax
• SAFEVAC – Western Australian Vaccine Safety Surveillance (WAVSS) System
• AusVaxSafety – RSV vaccine safety data
• Clinician Assist WA – Adverse Events Following Immunisation (AEFIs)

Author affiliations:

1. Communicable Disease Control Directorate, Western Australia Department of Health

References:

1. Simões EAF, Pahud BA, Madhi SA et al. Efficacy, Safety, and Immunogenicity of the MATISSE (Maternal Immunization Study for Safety and Efficacy) Maternal Respiratory Syncytial Virus Prefusion F Protein Vaccine Trial. Obstet Gynecol 2025. doi: 10.1097/AOG.0000000000005816
2. Son M, Riley LE, Staniczenko AP et al. Nonadjuvanted Bivalent Respiratory  Syncytial Virus Vaccination and Perinatal Outcomes. Infectious Diseases 2024 doi:10.1001/jamanetworkopen.2024.19268
3. Mapindra MP, Mahindra MP, McNamara P et al. Respiratory Syncytial Virus Maternal Vaccination in Infants below 6 Months of Age: Meta-Analysis of Safety, Immunogenicity, and Efficacy. Neonatology. 2024. doi: 10.1159/000536031