Vaccination for preterm infants

Preterm (premature) infants are those born at <37 weeks gestation. Extremely preterm infants are born at <28 weeks gestation.

Prematurity can increase the child’s risk of vaccine-preventable diseases.¹

Despite their immunological immaturity, preterm infants generally respond well to immunisation products.^2-4 Provided they are medically stable and there are no contraindications to vaccination, preterm infants should receive immunisation products according to the recommended schedule at their chronological age, without correction for prematurity.^5-7

Consider the child’s birth weight, the precise gestational age and the presence of any chronic medical condition(s) before giving immunisation products. When considering prematurity and birth weight, the need for additional doses for some vaccines is based on birth weight (e.g., hepatitis B vaccine), while for others it is based on prematurity (e.g. pneumococcal vaccine).

Vaccination is associated with an increased risk of apnoea in preterm infants who receive vaccines in hospital, particularly those receiving complex medical care or with a history of apnoea.

Apnoea is generally self-limiting in this setting, but is an expected adverse event following immunisation. Take measures to manage it by:^8-10 

• monitoring hospitalised preterm infants for apnoea or bradycardia for up to 48 hours after vaccination^10,11
• in infants who have a history of apnoea after vaccination, considering giving future vaccines under medical supervision^12,13

Vaccination is not associated with an increased risk of sudden infant death syndrome.^14,15

All preterm infants born at <28 weeks gestation are recommended to receive 4 doses of 13vPCV (13-valent pneumococcal conjugate vaccine), 15vPCV (15-valent pneumococcal conjugate vaccine) or 20vPCV (20-valent pneumococcal conjugate vaccine) and 2 doses of 23vPPV (23-valent pneumococcal polysaccharide vaccine).

The doses of 13vPCV, 15vPCV or 20vPCV should be given at 2, 4, 6 and 12 months of age.

The 1st dose of 23vPPV should be given at 4 years of age, and the 2nd dose given at least 5 years later. 

Children who were born at <28 weeks gestation do not need more pneumococcal vaccine doses after 5 years of age if they:

• do not have a chronic medical condition(s) and are not Aboriginal or Torres Strait Islander, and therefore are not at ongoing increased risk of pneumococcal disease 
• have received the extra pneumococcal vaccine doses to 5 years of age as recommended above

However, all children and adults who have chronic lung disease or certain other chronic medical conditions (whether related to preterm birth or not) should receive extra pneumococcal vaccine doses up to and beyond the age of 5 years. 

For more details, see:

• Pneumococcal disease
• Table. Catch-up schedule for pneumococcal conjugate vaccines for Aboriginal and Torres Strait Islander children living in NT, Qld, SA or WA ONLY, and children from all states/territories with any risk condition(s) for pneumococcal disease, aged <5 years
• Table. Risk conditions for pneumococcal disease

Low-birthweight preterm infants do not respond as well to hepatitis B–containing vaccines as full-term infants.^11,16,17

Low-birthweight infants (<2000 g) and/or infants born at <32 weeks gestation (irrespective of weight) are recommended to receive:

• hepatitis B vaccine at birth
• 3 doses of a hepatitis B–containing vaccine, at 2, 4 and 6 months of age
• a booster dose at 12 months of age 

There is no need to measure the hepatitis B surface antibody (HBs) titre after the primary series.

However, if measuring the antibody titre, do this at least 1 month after the 6-month dose.¹⁸ If the anti-HBs titre is <10 mIU per mL, give a booster dose.

Preterm infants born to hepatitis B surface antigen (HBsAg)–positive mothers should receive hepatitis B vaccine and hepatitis B immunoglobulin, as specified in Hepatitis B (see Hepatitis B).

Preterm infants have a high rate of underlying medical conditions that increase the risk of complications from influenza.¹⁹ These can include respiratory, cardiac and neurologic conditions. 

Preterm infants should receive influenza vaccine every year, starting at ≥6 months of age. 

Infants should receive 2 vaccine doses, at least 4 weeks apart, the 1st time they receive influenza vaccine, then 1 dose every year after that, as per the recommendation for all children <9 years of age (see Influenza).

Preterm infants can receive rotavirus vaccine at their chronological age without correction for prematurity. This includes hospitalised infants who are medically stable.

Strict upper age limits for vaccination apply, depending on which rotavirus vaccine the infant receives (see Rotavirus).

Preterm infants who have had a 3-dose primary schedule of Haemophilus influenzae type b (Hib) vaccines do not need to change the schedule. Preterm infants produce good antibody responses to all the antigens in Infanrix hexa and Vaxelis following administration at 2, 4 and 6 months of age.^1,20

If an extremely preterm and/or low-birthweight baby (<28 weeks gestation or <1500 g birth weight) received a 2-dose primary series of Hib vaccine (at 2 and 4 months of age), they should receive an extra dose at 6 months of age. That is, they should receive doses at 2, 4, 6 and 18 months of age.

Pre-term infants are at greater risk of severe RSV disease compared to full-term infants.²¹ There are two RSV specific monoclonal antibodies available to provide passive protection to infants: long-acting monoclonal antibody - nirsevimab (administered as a single dose) and short-acting monoclonal antibody - palivizumab (administered as 5 doses). Nirsevimab is preferred over palivizumab, but where nirsevimab is not available, palivizumab may be considered for extremely preterm infants.  

Pre-term infants (<32 weeks gestation) are recommended to receive nirsevimab, regardless of if their mother received maternal RSV vaccine in their pregnancy, after assessment by their treating doctor to confirm potential clinical benefit.

They are recommended to receive nirsevimab:

• shortly after birth if born prior to or during RSV season
• if born after the RSV season take into consideration the likelihood of out-of-season RSV infection and risk of severe disease, and consider delaying nirsevimab until just before the next RSV season if appropriate

For details of recommendations for nirsevimab use in other infants, see Respiratory Syncytial Virus.

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17. Blondheim O, Bader D, Abend M, et al. Immunogenicity of hepatitis B vaccine in preterm infants. Archives of Disease in Childhood. Fetal and Neonatal Edition 1998;79:F206-8.
18. Centers for Disease Control (CDC). Hepatitis B. In: Haber P, Schillie S, eds. Pink Book. Washington, DC: CDC; 2021. (Accessed 6 July 2023). https://www.cdc.gov/vaccines/pubs/pinkbook/hepb.html
19. Munoz FM. Influenza virus infection in infancy and early childhood. Paediatric Respiratory Reviews 2003;4:99-104.
20. Wilck MB, Xu ZJ, Stek JE, Lee AW. Safety and immunogenicity of a fully-liquid DTaP-IPV-Hib-HepB vaccine (Vaxelis™) in premature infants. Human Vaccines and Immunotherapeutics 2021;17:191-6.
21. Homaira N, Oei JL, Mallitt KA, et al. High burden of RSV hospitalization in very young children: a data linkage study. Epidemiology and Infection 2016;144:1612-21.