RSV and pneumococcal vaccines: comparable immune responses when administered together

Two vaccines on the same day or one month apart

This phase III trial was conducted at 38 centers in Belgium, Poland, Spain and the United States. Participants were randomly assigned to two groups: simultaneous vaccination or administration one month apart. The study was open-label, meaning the strategy used was not masked.

The vaccines studied were adjuvanted RSVPreF3, targeting RSV, and the 20-valent pneumococcal conjugate vaccine, PCV20. The primary endpoints concerned neutralizing antibodies against RSV types A and B and opsonophagocytic activity against the 20 pneumococcal serotypes, a measure of the ability of antibodies to promote bacterial clearance.

The immunological criteria were met

According to the abstract, all primary non-inferiority objectives were met. Antibody titer comparisons met the predefined margins for both RSV types and all 20 pneumococcal serotypes.

Non-inferiority does not mean that the responses were strictly identical. It indicates that their difference remained within limits considered acceptable by the protocol. The abstract provides neither detailed response values nor the margins used, limiting assessment of the magnitude of the differences.

Similar tolerability, without evidence of increased vaccination coverage

Safety profiles were similar between the groups. Most adverse events were mild to moderate and short-lived. Serious adverse events and potential immune-mediated diseases were rare and reported as unrelated to vaccination. However, the abstract does not provide their precise frequencies or the duration of follow-up.

These results support the possibility of administering these two vaccines together in the adults studied. However, the trial does not demonstrate that this approach actually increases vaccination coverage or reduces infections and hospitalizations to the same extent: the primary endpoints were immunological.

What we can take away

Simultaneous administration of these two vaccines meets the trial’s immunological criteria, with tolerability reported as similar. This supports the approach but does not demonstrate equivalent clinical efficacy.