VACCINE RESOURCE COMMITTEE

of the Edmonton Zone Medical Staff Association

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Respiratory Syncytial Virus Vaccine Question #4:

Why is vaccine protection important for infants?

RSV can cause severe infection in some people, including babies 12 months and younger (infants), especially premature infants.

RSV is the most common cause of bronchiolitis and pneumonia among infants and young children. RSV infects almost all infants by 2 years of age. In infants and young children, the younger the child, the higher the risk of hospitalization. The risk of medically attended RSV appears to be higher in infants with comorbidities compared to healthy term infants entering their first RSV season. However, the majority of infants and young children who require medical office or emergency department visits associated with RSV are born at term with no underlying comorbidities.

Prematurity is a notable risk factor for RSV hospitalization. Indeed, infants born at less than 30 weeks gestational age (wGA) have RSV hospitalization rates of 7.7 to 13.6% in the first year of life. Also at higher risk of RSV hospitalization are young children with chronic respiratory, cardiac or immunocompromising conditions. List 1 describes medical conditions that increase an infant's risk of severe RSV disease.

Most RSV infections are respiratory tract infections that present as nasal congestion, cough, low grade fever and loss of appetite and last approximately 1 to 2 weeks. Approximately 20 to 30% of infected infants develop bronchiolitis or pneumonia. Croup or otitis media may also occur.

Mortality is very low (6.9 per 1 million live births) in high income countries among children receiving supportive care. In Canada, approximately 2% of all infants are hospitalized with RSV in their first year of life. In some remote communities, RSV hospitalization rates have been as high as 5 to 17% of all live births.

The RSV monoclonal antibodies, nirsevimab or palivizumab (administered to the infant), or the RSVpreF (AbrysvoTM) vaccine (administered to the pregnant individual) can help protect infants from RSV disease by giving the infant antibodies, either via direct injection or transplacental transfer.

In Alberta the publicly funded program for protection focused on the highest risk infants, and the product available is palivizumab. Alternatively, pregnant women could receive the vaccine by purchasing through private pharmacies and administering after 32 weeks gestation, to protect their infant after birth. Programs for protection of high risk infants, and ideally all infants, are likely to evolve over time.

Source:

Government of Canada: Respiratory syncytial virus (RSV) vaccines: Canadian Immunization Guide