TABLE 4. Safety* of 1 dose of Pfizer respiratory syncytial virus RSVpreF vaccine in adults aged ≥60 years — multiple countries, 2021–2023.
| Safety event | Risk for event | ||
|---|---|---|---|
| RSVpreF recipients no./No. (%)† | Placebo recipients no./No. (%)§ | Relative risk (95% CI)¶ | |
| Serious AE** | 792/18619 (4.3%) | 749/18334 (4.1%) | 1.04 (0.94–1.15) |
| Severe reactogenicity events†† | 36/3673 (1.0%) | 24/3491 (0.7%) | 1.43 (0.85–2.39) |
| Inflammatory neurologic events§§ | 3/18622 (—)¶¶ | 0/18335 (—) | —¶¶ |
Abbreviations: AE = adverse events; GBS = Guillain-Barré syndrome.
* Safety events observed in Pfizer’s pivotal phase 3 trial (https://pubmed.ncbi.nlm.nih.gov/37018468/) and phase 1/2 trial (https://pubmed.ncbi.nlm.nih.gov/34932102/). There were no additional inflammatory neurologic events observed in any Pfizer clinical trials other than the two trials included. Additional data provided by Pfizer.
† Represents number of events and percent of all participants experiencing events observed among RSVpreF vaccine recipients across phase 3 and phase 1/2 trials.
§ Represents number of events and percent of all participants experiencing events observed among placebo recipients across phase 3 and phase 1/2 trials.
¶ Pooled relative risk for events in phase 3 and phase 1/2 trials.
** Serious AEs were defined as any untoward medical occurrence (during all available follow-up time [safety follow-up through February 2023] after injection in the phase 3 trial and 60 days for the phase 1/2 trial) that resulted in death, was life threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent disability or incapacity, or was a congenital anomaly or birth defect.
†† Severe reactogenicity events were defined as grade 3 or higher local reaction (injection site pain, redness and swelling) or systemic reaction (fever, fatigue or tiredness, headache, nausea, muscle pain, joint pain, vomiting, diarrhea, and other systemic event) recorded during days 0–7 after vaccination. For injection site redness and swelling, grade 3 corresponded to a diameter >3.9” (>100 mm) from e-diary or severe grade from adverse event case report form. For fever, grade 3 corresponded to a temperature >102°F (>38.9°C) from e-diary or severe grade from adverse event case report form. For all other reactions, grade 3 corresponded to reactions that prevented normal, everyday activities. Grade 4 event corresponded only to a fever >104°F (>40°C).
§§ Defined by the Advisory Committee on Immunization Practices Work Group as GBS (including GBS variants), chronic inflammatory demyelinating polyneuropathy, or acute central nervous system inflammation (e.g., transverse myelitis or acute disseminated encephalomyelitis) occurring ≤42 days after vaccination.
¶¶ Across all RSVpreF clinical trials, including trials other than the phase 3 and phase 1/2 trials summarized in this table, inflammatory neurologic events were reported in three of 20,255 adults ≤42 days after vaccination with RSVpreF (all in the phase 3 trial). The events included GBS, Miller Fisher syndrome (a GBS variant), and undifferentiated motor-sensory axonal polyneuropathy. Relative risk could not be calculated because no events were observed in the placebo-controlled comparator group.