One primary dose of PCV13 plus a booster held antibody levels to age five; PCV10 did not

Design

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

Population

354 of 600 HIV-unexposed South African children

Primary outcome

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

Effect

PCV13 1+1 non-inferior to 2+1 to age 5; PCV10 1+1 not non-inferior at ages 4 and 5

In a South African trial, 600 HIV-unexposed infants were randomised to one or two primary doses of PCV10 or PCV13, each followed by a 9-month booster. This extension measured serotype-specific IgG at ages 3, 4 and 5 in 354 children.

Both 1+1 PCV13 schedules, primed at 6 or 14 weeks, stayed non-inferior to 2+1 PCV13 up to age 5. Both 1+1 PCV10 schedules were non-inferior at 3 years but not at 4 or 5. With 2+1 schedules, PCV10 and PCV13 gave similar antibody levels for shared serotypes.

Reduced schedules save doses and cost, and the UK already uses 1+1. The finding supports that move for PCV13 in established programmes, but not for 10-valent vaccines. India's programme uses a 2+1 schedule, and because the result differed by vaccine, it gives no basis for changing that schedule.

• Follow the national schedule: 6 weeks, 14 weeks and a 9-month booster in India
• Do not skip a primary dose on the strength of this trial
• Complete catch-up doses for children who missed the primary series
• Remember antibody levels are a surrogate for protection, not disease outcomes

Why it matters

Dose-sparing schedules may not be interchangeable across pneumococcal vaccines.

Don't overread it

This measured antibodies in 59% of the original cohort at one centre; it does not show differences in disease.

The statistics, in plain English

Non-inferiority here meant the lower bound of the antibody ratio stayed above 0.5 for most serotypes, so the reduced schedule gave at least half the antibody of the full one. Loss to follow-up (41%) reduces precision and could bias results if those who stayed differed from those who left.

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