Neonates and infants aged <8 months whose mothers were not vaccinated at least 2 weeks before delivery, or who are at increased risk of severe disease, are recommended to receive passive immunisation with an RSV-specific monoclonal antibody
Nirsevimab is a long-acting RSV-specific monoclonal antibody that is recommended for infants who were born:
- to women who did not receive RSV vaccine during pregnancy
- within 2 weeks of the mother receiving RSV vaccine during pregnancy
Nirsevimab is also recommended for the following infants after assessment by their treating doctor to confirm potential clinical benefit:
- infants with risk conditions for severe RSV disease, regardless of maternal vaccination (see List. Conditions associated with increased risk of severe RSV disease in infants and young children)
- infants born to mothers with severe immunosuppression, where the immune response to maternally administered RSV vaccine was impaired (see People who are severely compromised)
- infants whose mothers have received RSV vaccine in pregnancy but have subsequently undergone a treatment, such as cardiopulmonary bypass or extracorporeal membrane oxygenation, that has led to loss of maternal antibodies
See Figure. Flowchart to guide which infants should receive nirsevimab in their 1st RSV season.
Administration of nirsevimab is likely to be most effective when given shortly after birth for infants born just before or during the RSV season. See Timing of RSV-specific monoclonal antibodies in infants.
Nirsevimab is not recommended for infants during the first 6 months of life if:
- the infant’s mother received RSV vaccine at an appropriate time during pregnancy, and
- the infant does not have a risk condition for severe RSV disease
Data are limited on the use of monoclonal antibody after maternal RSV vaccination, and the incremental benefit of this is uncertain. There is a gradual decline in protection derived from maternal RSV vaccination after birth due to antibody waning. Therefore, minimal protection is likely beyond 6 months of age. When nirsevimab is given to an infant with a risk condition who was born to a mother who received RSV vaccine in pregnancy, consideration should be given to the timing of administration in relation to onset of the RSV season to maximise the duration of protection.
Figure. Flowchart to guide which infants should receive nirsevimab in their 1st RSV season
This figure is a flow chart that provides guidance on which infants should receive nirsevimab in their first RSV season.
The starting point is a box with a question about whether the mother was vaccinated with the RSV vaccine Abrysvo, at least 2 weeks prior to delivery of the infant.
If the answer is no and the mother has delivered the baby less than two weeks after receiving the RSV vaccine, then an arrow points the reader to a new box. This new box says that the infant is recommended nirsevimab. It also provides the dose amounts by infant weight. For infants weighing less than 5 kilograms, they should receive 50 milligrams of nirsevimab. For infants weighing more than 5 kilograms, they should receive 100 milligrams of niresevimab.
If the answer is yes and the mother has delivered the baby at least two weeks after receiving Abrysvo, then there is a second question about if the infant remains at risk of severe RSV disease. There are two scenarios in which the infant may remain at risk, one is that the infant has a listed risk condition, and two is that the infant has suboptimal RSV antibodies because of certain conditions of their mother. There are seven risk conditions listed. One is preterm birth, which applies to infants born before 32 weeks gestational age. Two is haemodynamically significant congenital heart disease. Three is significant immunosuppression such as solid organ transplant or a primary immune deficiency such as severe combined immunodeficiency. Four is chronic lung disease that requires ongoing oxygen or respiratory support. Five is neurological conditions that impair regulatory function. Six is cystic fibrosis with severe lung disease or if weight for length is less than the 10th percentile. Seven is trisomy 21 or another genetic condition that increases the risk of RSV. The other scenario in the box has two conditions for which an infant may have suboptimal RSV antibodies. One is that they were born to a mother who was severely immunosuppressed when she received the RSV vaccine. Two is that the infant had a treatment associated with loss of maternally derived antibodies such as cardiopulmonary bypass or extracorporeal membrane oxygenation.
If the answer is no and the infant does not fall into one of those two scenarios, then the arrow points to a new box saying the infant is not recommended nirsevimab.
If the answer is yes and the infant does fall into one of those two scenarios, then the arrow points to the box that says the infant is recommended nirsevimab and provides the dose amounts by infant weight, as described previously.