A one-dose-plus-booster PCV13 schedule kept non-inferior immunity to age five

Design

Extended follow-up of an open-label, single-centre, non-inferiority randomised trial

Population

354 of 600 children followed to age 5 (PCV10 or PCV13, one-dose or two-dose primary series plus booster)

Primary outcome

Serotype-specific IgG geometric mean concentrations at ages 3, 4 and 5 years

Effect

PCV13 one-dose schedules non-inferior to age 5; PCV10 one-dose schedules not non-inferior at 4 and 5 years

This extended follow-up of a South African randomised trial measured serotype-specific IgG at ages 3, 4 and 5 years in children who had received pneumococcal conjugate vaccine as one primary dose plus a booster at 9 months (given at 6 or 14 weeks), or two primary doses plus a booster, using PCV10 or PCV13. Of 600 original participants, 354 (59%) took part in follow-up.

Both PCV13 one-dose schedules stayed non-inferior to the two-dose schedule to age 5. Both PCV10 one-dose schedules met non-inferiority at 3 years but not at 4 and 5 years. PCV10 and PCV13 gave similar IgG concentrations for the ten shared serotypes on the two-dose schedule, and PCV13 outperformed PCV10 across most serotypes in the one-dose groups.

The measure is antibody concentration, not disease, and the trial was single-centre with infants not exposed to HIV and with substantial loss to follow-up. The findings support reduced-dose schedules in settings with established programmes using PCV13. Which schedule an Indian child follows is set by national policy, and this trial does not argue for individual departure from it.

• Follow the schedule set by the national or state immunisation programme for the vaccine in use.
• Make sure the booster dose is not missed; it was given to every child in this trial.
• Do not reduce doses on an individual basis on the strength of this trial.
• Note that results differed by vaccine: PCV10 single-dose schedules were less durable.

Why it matters

It tests whether fewer doses keep immunity through the age when children are still at risk, a question that drives cost and coverage.

Don't overread it

Antibody concentrations are a surrogate for protection, and the trial was a single-centre study in children without HIV exposure.

The statistics, in plain English

Non-inferiority here meant the lower bound of the 95% interval for the antibody ratio stayed above 0.5 for most serotypes. It tells you that antibody levels were not much lower, not that disease protection was identical. About 4 in 10 children were lost from the original cohort, which can bias the comparison.

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