# Summary of the National Advisory Committee on Immunization (NACI) Statement: Recommendations on the use of pneumococcal vaccines in adults, including Pneu-C-21

## TL;DR

The paper summarizes recommendations for pneumococcal vaccines in adults, including the new 21-valent vaccine Pneu-C-21, based on its safety, immunogenicity, and cost-effectiveness.

## Contribution

The paper provides updated evidence-based recommendations for pneumococcal vaccine use in adults, incorporating new data on Pneu-C-21 and its comparative effectiveness.

## Key findings

- Pneu-C-21 shows comparable immunogenicity to Pneu-C-20 for shared serotypes and better responses for unique ones.
- Safety profiles of Pneu-C-21 and Pneu-C-20 are similar to other pneumococcal vaccines.
- NACI recommends including either Pneu-C-20 or Pneu-C-21 in adult immunization programs for high-risk groups.

## Abstract

Pneumococcal disease in adults includes invasive pneumococcal disease (IPD), an acute and serious communicable disease with manifestations such as meningitis, bacteremia and bacteremic pneumococcal pneumonia. There are more than 100 different serotypes, and the extent of protection provided by a pneumococcal vaccine depends on the vaccine formulation. In July 2024, Health Canada authorized a 21-valent pneumococcal conjugate vaccine (Pneu-C-21), which followed the recent introduction of a 20-valent vaccine (Pneu-C-20) authorized in 2022.

The National Advisory Committee on Immunization (NACI) reviewed evidence on the epidemiology of IPD in Canada, immunogenicity and safety of Pneu-C-21, and the cost-effectiveness of different pneumococcal vaccines in adult immunization programs. NACI has also considered additional factors, including ethics, equity, feasibility, and acceptability (EEFA).

Differences in the distribution of serotypes causing IPD have been observed before and after the COVID-19 pandemic. The Pneu-C-21 demonstrated comparable immunogenicity to Pneu-C-20 for shared serotypes and higher responses for unique serotypes. The safety profiles of both vaccines are expected to be similar to other pneumococcal vaccines, and the cost-effectiveness of Pneu-C-21 and Pneu-C-20 will depend on regional serotype distribution. The overall impact of Pneu-C-21 compared to Pneu-C-20 is uncertain, but likely to vary over time with age, risk factors, and geography.

NACI now recommends including at least one of Pneu-C-20 or Pneu-C-21 in adult pneumococcal immunization programs. One dose should be given to adults 65 years and older and those 18 to under 65 years at increased IPD risk, regardless of previous pneumococcal vaccination history.