Incorrect Administration of Adult RSV Vaccines to Young Children.

In May 2023, the US Food and Drug Administration (FDA) approved the first vaccines for the prevention of respiratory syncytial virus (RSV)-associated lower respiratory tract disease (LRTD) for use in adults aged ≥60 years: 1 manufactured by GSK (Arexvy)1 and 1 by Pfizer (Abrysvo).2 In July 2023, FDA approved nirsevimab (Beyfortus, Sanofi, and AstraZeneca), a long-acting monoclonal antibody for passive immunization to prevent RSV-associated LRTD among infants and children aged <24 months.3 In August 2023, FDA approved the Pfizer RSV vaccine for pregnant persons, with administration indicated at 32 to 36 weeks' gestation to prevent RSV-associated LRTD and severe LRTD in infants aged <6 months.2 GSK RSV vaccine is not approved for use during pregnancy.1 In August 2023, the Advisory Committee on Immunization Practices and the Centers for Disease Control and Prevention (CDC) recommended nirsevimab for all infants aged <8 months who are born during or entering their first RSV season and for infants and children aged 8 through 19 months entering their second RSV season who are at increased risk for severe RSV disease.4 Administration of either maternal Pfizer RSV vaccine during pregnancy at 32 through 36 weeks' gestation or nirsevimab to the infant is recommended to prevent RSV-associated LRTD in infants, but both are not needed for most infants.5 Pfizer and GSK RSV vaccines are not approved for use in infants and young children.1,2Health care facilities that provide preventive care for children and adults might store and administer Pfizer and GSK RSV vaccines, other routine vaccines, and nirsevimab; thus, the potential exists for Pfizer or GSK RSV vaccines to be administered in error to infants and young children.The Vaccine Adverse Event Reporting System (VAERS) is a national, spontaneous reporting (passive surveillance) system comanaged by CDC and FDA.6 VAERS reports are classified as serious if any of the following are reported: hospitalization, prolongation of hospitalization, life-threatening illness, permanent disability, congenital anomaly or birth defect, or death.7 To assess vaccine administration errors of Pfizer or GSK RSV vaccine use in infants and young children aged <2 years, the VAERS database was searched for reports of children aged <24 months who received an RSV vaccine, and a text string search was conducted for the words "infant," "child," "newborn," "neonate," "pediatric," "month," and "peds" within the fields' symptom text or laboratory data for those reports where age was not provided. This activity was reviewed by CDC and was conducted consistent with applicable federal law and CDC policy.8From August 21, 2023, to March 18, 2024, the VAERS database included 34 reports of administration errors indicating that either Pfizer or GSK RSV vaccine had been administered to children aged <2 years; 31 were in infants aged <8 months (Table 1). For 21 reports, a family medicine practice was the vaccination location. Twenty-seven reports involved Pfizer and 7 involved GSK RSV vaccine. Twenty-seven reports included no adverse health events. Seven reports described at least 1 adverse health event, including a serious report of an infant with a history of congenital heart disease hospitalized for cardiorespiratory arrest within 24 hours after receipt of GSK RSV vaccine in addition to routine childhood vaccines (Table 1). Six reports described injection site or systemic reactions (eg, irritability) after administration of Pfizer or GSK RSV vaccine.This review found infrequent reports of Pfizer and GSK RSV vaccines administered to infants and young children aged <2 years in error. VAERS limitations include reporting biases (over- or underreporting) and inconsistency in quality and completeness of reports.6 Health care providers should not administer Pfizer or GSK RSV vaccine to infants and young children.1,2,5 Administration errors are preventable with proper education and training, ordering only products that are approved for the patient population a facility serves, electronic health record alerts or warnings, close attention to labeling, storage best practices, and other preventive measures.9 To increase awareness and help prevent these vaccine administration errors, CDC is working to educate health care providers administering vaccinations and nirsevimab to young children aged <2 years.10 Health care providers are encouraged to report vaccination errors to VAERS,11 including those involving Pfizer or GSK RSV vaccines.12 CDC and FDA will continue to monitor VAERS for these administration errors.6We thank Elaine Miller, Tom Shimabukuro, John Su, Hannah Brown, and Carol Ennulat, CDC; Immunization Safety Office, CDC; Meghna Alimchandani and Narayan Nair; Center for Biologics Evaluation and Research, FDA; and General Dynamics Information Technology.