Make Way for New Pneumococcal Conjugate Vaccines

Frank Bell, MD, FAAP, WCAAP Vaccine Committee Co-Chair

What are the new Pneumococcal Vaccines and why were they introduced?

The last 18 months have brought significant change to pediatric pneumococcal immunization with the introduction of two new conjugate vaccines (PCV15, Vaxneuvance® and PCV20, Prevnar 20®) which replace PCV13, accompanied by new recommendations for children at increased risk for serious pneumococcal disease including those with chronic medical conditions or with immune-deficiency states, described collectively as individuals with ‘risk conditions.’

Earlier conjugate pneumococcal vaccines (PCV7 & PCV13) have been highly successful in reducing the rates of pneumococcal disease from serotypes contained in the vaccines, but non-vaccine serotypes continue to cause significant disease in children and adults of all ages. The new higher-valency conjugate vaccines PCV15 & PCV20 cover a broader range of pneumococcal serotypes and are expected to provide enhanced protection against pneumococcal disease in childhood and adolescence.

What’s so special about Conjugate Vaccines?

All currently-available pneumococcal vaccines use capsular polysaccharide antigens to induce a protective serotype-specific immune response. In contrast to the ‘plain’ unconjugated pneumococcal polysaccharide vaccine PPSV23 (Pneumovax®) introduced in the 1980s, pneumococcal conjugate vaccines contain capsular polysaccharides, each covalently-linked to a carrier protein. For all currently-licensed pneumococcal conjugate vaccines, this protein is a variant of diphtheria toxin, designated CRM197. The process of conjugation or linking of the saccharide polymer to a protein subunit recruits T-lymphocytes to enhance the immune response to vaccine administration.

T-cell ‘help’ leads to significantly improved immunogenicity, particularly in young infants, inducing long-term memory responses at all ages and unlike PPSV23, conjugate vaccine use reduces rates of pneumococcal carriage providing population-level or ‘herd’ immunity by reducing the transmission of pneumococci to unimmunized individuals including grandparents and other adults in the community.

Who should receive the new vaccines & when should they receive them?

The newer higher-valency pneumococcal conjugate vaccines, PCV15 and PCV20, replace PCV13 in the primary vaccine series for infants aged 2 months to 2 years, and for children, teens and young adults with underlying medical conditions associated with an increased risk of pneumococcal disease including those with immunocompromising disorders. For those patients identified with risk conditions, individuals over the age of 2 years may be immunized with either a single dose of PCV20 or with PCV15 followed by a later dose of PPSV23.

Is there still a role for PCV13?

PCV13 may still be given if neither PCV15 or PCV20 are available, but in all other circumstances PCV13 has been replaced by the new multivalent vaccines, expected to provide broader serotype protection against pneumococcal disease.

What about for PPSV23?

The principal role for PPSV23 in pediatric patients is to follow an earlier dose of PCV15 for at-risk individuals in order to extend sero-type protection still further, respecting a minimum interval of at least 8 weeks between the administration of the two vaccines. If both a conjugate (PCV15) and polysaccharide (PPSV) vaccine are planned, the conjugate vaccine should always proceed administration of PPSV23. These vaccines should not be administered together at the same visit.

Pneumococcal vaccine recommendations for high-risk children and teens seem a bit complicated… how do I know what to give?

If uncertain about what your patients might need or how to navigate ‘best-protection’ against pneumococcal disease, try the CDC’s online resource PneumoRecs VaxAdvisor for ready-access to personalized advice.