Respiratory syncytial virus (RSV) immunization is given at different times depending on who needs protection. In the United States, the pregnancy vaccine is given at weeks 32–36, usually from September through January. Eligible babies receive a protective antibody shortly before RSV season or soon after birth during the season. Older adults who qualify can receive a one-time RSV vaccine, ideally in late summer or early fall.
The best time for RSV immunization depends on age, pregnancy, the local pattern of RSV infections, and the recommendations in your country. Protection for babies can come from vaccination during pregnancy or an injection of protective antibodies after birth. Older adults may receive an RSV vaccine to help prevent serious illness.
When is the RSV vaccine given during pregnancy?
In the United States, the Centers for Disease Control and Prevention (CDC) recommends one dose of the maternal RSV vaccine, Pfizer's Abrysvo, between 32 weeks and 36 weeks and 6 days of pregnancy. For most of the continental United States, vaccination is recommended from September through January, when the timing is intended to help protect babies during their first RSV season.
According to the CDC's guidance on RSV vaccination during pregnancy, the vaccine helps protect the baby because the pregnant person's body makes antibodies that cross the placenta before birth. These antibodies provide the baby with early protection against severe RSV disease. Timing matters because the baby needs time to receive these protective antibodies before delivery.
Recommendations can differ outside the United States. The World Health Organization (WHO) recommends giving the maternal RSV vaccine during the third trimester, from 28 weeks of pregnancy onward in most settings. The precise starting week and timing should follow the national vaccination programme and the vaccine's approved guidance in the country where care is provided.
When should a baby receive RSV immunization after birth?
A baby can be protected through the mother's vaccination during pregnancy or by receiving a long-acting RSV antibody directly. The antibody injection provides protection without requiring the baby to produce the antibodies independently. These products are called monoclonal antibodies; although they are not vaccines, they are an important form of RSV immunization.
According to the CDC's guidance on immunizations to protect infants, most babies need only one of the two approaches. In the United States, an infant antibody is generally recommended for babies younger than 8 months who are entering their first RSV season and whose mothers did not receive the RSV vaccine during pregnancy, whose vaccination status is unknown, or who were born within 14 days of maternal vaccination.
What is the best time for an infant antibody injection?
In most of the continental United States, infant RSV antibodies are given from October through March. Babies born during these months should ideally receive the injection during their birth hospitalization or within their first week of life. Babies born outside this period who are eligible for protection are generally given the injection shortly before the next RSV season begins, often in October or November.
The CDC's clinical guidance for infants and young children explains that local public health authorities may adjust these months when RSV activity follows a different seasonal pattern. The appropriate timing may therefore differ in tropical climates or other locations where RSV circulates outside the usual fall-to-spring period.
Do some children need RSV protection during their second season?
Some children aged 8–19 months who have an increased risk of serious RSV illness may be eligible for nirsevimab before or early in their second RSV season. Eligibility depends on specific medical circumstances, including certain chronic lung conditions related to prematurity, severe immune problems, and certain cases of cystic fibrosis. The child's healthcare professional should determine whether another dose is appropriate.
When should older adults receive an RSV vaccine?
In the United States, the CDC recommends one dose of an approved RSV vaccine for all adults aged 75 years and older and for adults aged 50–74 who have an increased risk of severe RSV illness. Risk factors can include certain chronic heart or lung conditions, a weakened immune system, and residence in a nursing home. The recommendation depends on age and health circumstances rather than on a single age-based schedule for everyone.
According to the CDC's RSV vaccine guidance for adults, eligible adults can receive the vaccine at any time of the year, although late summer and early fall are preferred in most of the continental United States. This timing allows protection to develop before RSV infections usually increase in the community.
RSV vaccination for eligible older adults is not currently an annual vaccination in the United States. People who have already received an RSV vaccine, including during a previous RSV season, are not currently advised to receive another dose routinely. Recommendations and approved age groups can differ by country, so adults should check the guidance that applies where they live.
Does everyone need RSV immunization at the same time?
No. Pregnancy vaccination is scheduled according to gestational age and, in many countries, the expected RSV season. Infant antibody injections are timed around birth and local RSV activity, while older adults receive vaccination according to age, risk factors, and national recommendations.
For most babies in the United States, maternal vaccination or an infant antibody injection is sufficient; both are not routinely needed. A healthcare professional can help families choose the appropriate option based on when the mother was vaccinated, when the baby was born, and the baby's eligibility for preventive antibodies.
How can you find the right RSV immunization date?
Ask your obstetrician, pediatrician, or primary care professional which RSV prevention schedule applies to you or your family. During pregnancy, confirm the recommended gestational weeks and seasonal window. For a newborn, ask whether maternal vaccination provided enough time for antibody transfer or whether the baby should receive an antibody injection. For an older adult, check eligibility and whether an RSV vaccine has already been received.
Because RSV circulation, vaccine approvals, and public health programmes differ between countries and regions, a schedule published for the United States may not be suitable elsewhere. Local clinical guidance is particularly important when planning protection in places with tropical or less predictable RSV seasons.