The common respiratory virus, known as the respiratory syncytial virus (RSV), typically causes upper respiratory illnesses; however, in certain populations-such as infants and older adults—it can lead to significant lower respiratory tract illnesses (LRTIs). To date, no approved pediatric vaccine or antiviral therapy exists for severe RSV disease, except in cases involving extremely immunocompromised patients.

RSV causes annual outbreaks of respiratory infections across all age groups and ranks among the most frequent causes of respiratory illnesses in children. In the United States, an estimated 58,000-80,000 children younger than 5 years are hos pitalized annually due to RSV infection, with some requiring oxygen, intravenous fluids, or even mechanical ventilatory support. Hospitalization rates are highest among infants aged 0-6 months. RSV is estimated to cause 100-300 deaths annually in United States infants younger than 5 years, especially those aged 6 months or younger (Jones et al., 2023). Additionally, subsequent bacterial infections, inappropriate antibiotic use, and chronic respiratory diseases such as asthma have been linked to RSV sickness in early infancy (Wildenbeest et al., 2023).

In August 2023, the U.S. Food and Drug Administration (FDA) authorized Pfizer's Abrysvo RSV vaccine for use in pregnant women. The Centers for Disease Control and Prevention (CDC) subsequently recommended vaccination during pregnancy to protect newborns from severe RSV disease (Kampmann et al., 2023). This editorial briefly discusses RSV vaccination during pregnancy, which is likely to be introduced domestically in the near future.

On August 3, 2023, the Centers for Disease Control and Prevention CDC recommended nirsevimab, a long-acting monoclonal antibody for the prevention of RSV infection in newborns and young children at elevated risk of RSV-related complications. According to the CDC guidance, a single dose of nirsevimab is advised for all infants younger than 8 months of age born during or entering their first RSV season. For infants born during the RSV season, the optimal time for administration is at birth or during the first week of life. Nirsevimab may be administered to all infants in this age group—regardless of gestational age or underlying medical conditions—if it was not given at birth. During the 2023-2024 RSV season, the CDC also recommends niresevimab for infants born to mothers who received maternal RSV vaccination in the following special cases: (1) if the infant is born with 14 days after maternal vaccination, (2) if there is concern that the mother's immune response to the vaccine was inadequate, or (3) if there is a medical condition that could interfere with the transfer of antibodies from the mother to the fetus. A dosage of nirsevimab is also recommended during the second RSV season for children aged 8-19 months who are at increased risk of developing severe RSV disease, such as those who are severely immunocompromised. According to data from the New Vaccine Surveillance Network and the Virtual SARS-CoV-2, Influenza, and Other Respiratory Viruses Network, nirsevimab was found to be 91%-98% effective in preventing RSV-associated hospitalizations among newborns during their first RSV season in 2023-2024. The American Academy of Pediatrics continues to recommend palivizumab, another monoclonal antibody therapy, for preterm infants born before 29 weeks of gestation and for certain infants under 24 months of age who are at a higher risk of hospitalization for RSV infection (Jones et al., 2023).

For the 2024-2025 RSV season, all newborns should receive nirsevimab or protection via maternal RSV vaccination to prevent severe RSV disease. Two safe and effective options exist to protect infants from RSV infection during this season, with no preferred method specified by the CDC. Expectant mothers should be informed about RSV and its risks to infants. Clinicians should clarify the differences between RSV, influenza, and coronavirus disease 2019 (COVID-19), emphasizing the need for distinct vaccinations for each. The benefits of maternal RSV immunization, a safe and efficient method to prevent severe LRTI in infants up to 6 months of age, should be discussed by clinicians with their patients. In cases where maternal RSV vaccination is not administered during pregnancy or has already been received, clinicians should advise patients on nirsevimab as a safe and effective option for infants. If nirsevimab availability is limited during the season, the advantages of maternal vaccination should be highlighted. Patient preference is critical when deciding between maternal RSV vaccination, nirsevimab for the infant, or both. Expectant mothers who plan to use nirsevimab for their infants are not required to receive the maternal RSV vaccine during pregnancy.

The CDC does not recommend a second dose of the maternal RSV vaccine during subsequent pregnancies for women previously vaccinated. Infants born to unvaccinated mothers during the current pregnancy should receive nirsevimab between October and March (preferably at birth for infants born October-March or in October for those born April- September). The maternal RSV vaccine may be administered concurrently with Tdap, COVID-19, and/or influenza vaccine during the same visit (Fleming-Dutra et al., 2023)

To prevent RSV LRTI in infants, the American College of Obstetricians and Gynecologists (ACOG) recommends a single dose of Pfizer's Abrysvo vaccine for eligible pregnant women between 32 0/7 and 36 6/7 weeks of gestation, who do not have a scheduled delivery within 2 weeks, administered seasonally. The maternal RSV vaccine is available throughout the 2024-2025 RSV season for expectant mothers not vaccinated during the 2023-2024 season. In most of the continental United States, the RSV season spans September to March, with eligible pregnant women receiving the vaccine between September and January.

If the maternal RSV vaccine is administered during the 2023-2024 RSV season, a subsequent dose in later pregnancies is not recommended. Nonetheless, nirsevimab should be administered to infants during the respiratory season of 2024-2025. Monoclonal antibody injections and maternal vaccinations are not necessary for most infants. However, infants born fewer than 14 days after maternal vaccination should receive nirsevimab. This is because the earliest time for maternal RSV vaccination is 32 0/7 weeks of gestation, and at least 14 days are needed for the development and transplacental transfer of protective maternal antibodies.

There are several implementation factors to consider when introducing a new vaccine into a maternal vaccination platform. ACOG encourages obstetrician-gynecologists to work collaboratively with their administrators and staff to develop an implementation plan that ensures patient access to all recommended maternal vaccines.

In Korea, RSV infection rates have increased the urgency for vaccine introduction. According to the Korea Disease Control and Prevention Agency, RSV cases increased from 99 (January 29-February 4, 2025) to 214 (February 26-March 4, 2025) (Statistics Korea, 2025), an 8-fold increase compared to the same period in 2024. Typically, RSV infections peak between October and January, but in 2025, cases persisted into March, indicating an atypical trend. As a result, calls for domestic RSV vaccine introduction have intensified. Despite this urgency, phase 3 clinical trials and approval processes are expected to delay domestic vaccine availability by 1-2 years. Nirsevimab (Beyfortus), jointly developed by the British com pany AstraZeneca and the French Sanofi, has received product approval from the Ministry of Food and Drug Safety. Therefore, Beyfortus is likely to be the first RSV vaccine to be commercialized in Korea. This is a pediatric RSV vaccine, and the administration of RSV-preventive antibody injections for all infants under 12 months of age has already begun in Korea this year.

Several RSV vaccines are anticipated for release in South Korea, including GSK's Arexvy, Moderna's mResvia, and Pfizer's Abrysvo, with estimated vaccination cost of 300,000- 400,000 Korean won (KRW), up to 10 times the cost of a typical flu vaccine (30,000-40,000 KRW). A medical professional emphasized, “herpes zoster, pneumococcal, and RSV vaccines have high preventive effects, but the vaccination rate is low due to the burden of price,” and “If government support is expanded, more citizens can benefit.” Experts, including those from the Korean Society for Infectious Diseases, have suggested that expanding health insurance coverage should be considered from a long-term perspective, taking into account the preventive benefits of the newly released herpes zoster, pneumococcal, and RSV vaccines. Meanwhile, there is growing international momentum to increase public funding for costly vaccines.

Beyond cost, promoting RSV vaccine effectiveness among pregnant women presents a challenge. Since influenza, whooping cough, and COVID-19 vaccines are already recommended during pregnancy, adding another vaccine may feel burden-some. Therefore, consultation with healthcare providers in clinical settings is essential. As further studies continue to support the effectiveness RSV vaccination, it is likely to gain natural acceptance—similar to other vaccines currently administered during pregnancy.

A growing number of mandatory checks must be performed during pregnancy to safeguard the health of both the fetus and the mother. To prevent RSV LRTI in infants, the ACOG recommends a single dose of Pfizer's RSV vaccine (Abrysvo) for eligible pregnant women between 32 0/7 and 36 6/7 weeks of gestation, provided they do not have a scheduled delivery within 2 weeks. The Maternal RSV vaccination has now been incorporated into prenatal care and is expected to reduce serious RSV infections in newborns. Obstetricians should provide patient education related to RSV vaccination in the clinic to help pregnant women make informed decisions.

Conflict of Interest: The author has nothing to disclose.