Is the RSV vaccine safe, and what do the trials show?

Is the RSV vaccine safe, and what do the trials show?

Respiratory syncytial virus (RSV) is a common cause of lower respiratory tract infections in older adults and young infants. With recent approvals of two RSV vaccines for older adults (Arexvy by GSK and Abrysvo by Pfizer) and one for maternal immunization (Abrysvo), many people are asking, “is the RSV vaccine safe?” Below, we review the clinical trial data, safety monitoring, and what you need to know.

Clinical trial design and participant groups

Both Arexvy and Abrysvo underwent large Phase 3 trials involving tens of thousands of participants. Trial designs focused on:

• Age group
  • Adults aged 60 years and older (both vaccines)
  • Pregnant people vaccinated at 32–36 weeks gestation (Abrysvo)

• Primary endpoints
  • Prevention of RSV-associated lower respiratory tract disease (LRTD)
  • Reduction in severe RSV illness leading to hospitalization or death

• Safety monitoring
  • Solicited adverse events for 7 days after vaccination (injection-site pain, fatigue, headache)
  • Unsolicited adverse events for 28–30 days
  • Serious adverse events (SAEs) tracked for 12 months

Key findings on safety and efficacy

1. Safety in older adults (60 years and up)

Arexvy (GSK) trial results:

• Participants: ~37,000 adults
• Efficacy: 82.6% reduction in RSV-LRTD cases over one RSV season
• Common side effects (in ≥10% of vaccine recipients):
  • Injection-site pain (60%)
  • Fatigue (30%)
  • Myalgia (24%)
  • Headache (20%)
• Severe adverse events: Balanced between vaccine and placebo groups
• Deaths: Similar numbers in both groups; none linked to the vaccine

Abrysvo (Pfizer) trial results:

• Participants: ~34,000 adults
• Efficacy: 67% reduction in RSV-LRTD cases across two RSV seasons
• Common side effects:
  • Injection-site pain (50–55%)
  • Fatigue (25%)
  • Headache (18–20%)
  • Gastrointestinal symptoms (nausea, diarrhea; 5–10%)
• Serious adverse events: Equally distributed between vaccine and placebo
• No safety signals: No increase in Guillain-Barré syndrome (GBS) or other neurological events

2. Safety in pregnant people and infants

Abrysvo maternal immunization trial:

• Participants: ~7,000 pregnant individuals vaccinated at 32–36 weeks
• Efficacy:
  • 81% reduction in severe RSV-LRTD in infants through 90 days of life
  • 69% reduction through 180 days
• Maternal side effects: Similar profile to older adults (injection-site pain, fatigue)
• Pregnancy outcomes:
  • Preterm birth rates similar between vaccinated and placebo groups
  • No increase in preeclampsia, gestational diabetes, or stillbirth
• Infant safety:
  • Rates of neonatal adverse events and congenital abnormalities were comparable
  • No vaccine virus transmission risk (non-live, protein-based vaccines)

Post-marketing surveillance and ongoing monitoring

Since FDA approval, both vaccines have been monitored through:

• Vaccine Adverse Event Reporting System (VAERS)
• Vaccine Safety Datalink (VSD)
• Manufacturer safety updates

So far:

• No new safety concerns have emerged
• Rates of serious events remain very low and consistent with trial findings
• Continued monitoring ensures early detection of rare side effects

Common side effects and what to expect

Most side effects are mild to moderate and resolve within 1–3 days:

• Injection-site pain or tenderness
• Mild fatigue or muscle aches
• Headache
• Occasional low-grade fever in older adults

These reactions are signs your immune system is responding. If symptoms are bothersome, over-the-counter pain relievers (acetaminophen or ibuprofen) can help, unless contraindicated for other health reasons.

Addressing concerns: is the RSV vaccine safe?

Based on large-scale trials and real-world data:

• The RSV vaccines have a strong safety profile in older adults and pregnant people.
• No patterns of serious or long-term harm have been linked to vaccination.
• Rates of adverse events are comparable to other adult vaccines (e.g., influenza, shingles).

Health agencies such as the U.S. Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC) recommend RSV vaccination for:

• Adults aged 60 years and older
• Pregnant people at 32–36 weeks gestation, to protect infants early in life

Who should consider getting vaccinated?

• Adults 60 years and up, especially those with chronic heart or lung conditions
• Pregnant people planning to deliver during RSV season
• Caregivers and household contacts of infants younger than 6 months

Speak with your healthcare provider if you:

• Have a history of severe allergic reactions to any vaccine component
• Are currently experiencing a moderate or severe acute illness (you may need to wait until recovery)

Tips for a smooth vaccination experience

• Schedule the vaccine before or early in RSV season (typically autumn to winter months)
• Stay hydrated and rest if you feel mild side effects afterward
• Report any unexpected or severe reactions to your healthcare provider promptly

When to seek medical attention

While most side effects are minor, contact a doctor if you experience:

• Signs of a severe allergic reaction (hives, facial swelling, difficulty breathing)
• High fever (>39°C/102.2°F) lasting more than 2 days
• New or worsening shortness of breath, chest pain, or other alarming symptoms

For non-emergency concerns or to explore your symptoms in detail, you might consider a free, online symptom check, using the doctor approved Ubie Symptom Checker.

Final thoughts

The question “is the RSV vaccine safe?” is answered clearly by the robust data from tens of thousands of trial participants and ongoing safety monitoring. The vaccines offer strong protection against serious RSV illness with an acceptable side-effect profile, similar to many common adult vaccines.

If you have any serious or life-threatening symptoms, or if you’re unsure whether the RSV vaccine is right for you, please speak to a doctor. Your healthcare provider can help you weigh benefits and risks based on your personal health history.