- Design
- Extended follow-up of an open-label, non-inferiority randomised trial
- Population
- 354 HIV-unexposed South African children, randomised as infants
- Primary outcome
- Serotype-specific IgG to age 5 years, 1+1 vs 2+1 schedules
- Effect
- PCV13 1+1 non-inferior to age 5; PCV10 1+1 not non-inferior at 4 and 5 years
An extended follow-up of an open-label randomised trial in South Africa, in The Lancet Child & Adolescent Health (September 2026), measured serotype-specific antibody up to age five in 354 of 600 HIV-unexposed infants originally randomised to one primary dose (at 6 or 14 weeks) or two primary doses of PCV10 or PCV13, all with a booster at nine months.
Both PCV13 1+1 schedules remained non-inferior to PCV13 2+1 until age five. Both PCV10 1+1 schedules met non-inferiority at three years but not at four or five. With two primary doses, PCV10 and PCV13 gave similar antibody levels for shared serotypes; in the single-dose groups PCV13 outperformed PCV10 across most serotypes.
Antibody concentration is a correlate, not disease protection, and only 59% of the original cohort were followed. But the finding matters for programmes considering reduced schedules, which the UK has already adopted: the vaccine product determines whether a 1+1 schedule holds.
- Follow the national PCV schedule — reduced schedules depend on the specific vaccine used
- A 1+1 schedule held with PCV13 but not with PCV10 in this trial
- Make sure the booster dose is given on time; reduced schedules depend on it
- Catch up missed PCV doses rather than restarting the series
Why it matters
It shows reduced PCV schedules are product-specific, which matters to any programme weighing cost against dose number.
Don't overread it
Antibody levels are a surrogate for protection, and 41% of the original cohort were not followed.
The statistics, in plain English
Non-inferiority here means the lower 95% confidence limit of the ratio of antibody levels (reduced vs full schedule) stayed above 0.5 for most serotypes. PCV10 1+1 fell below that bar at ages four and five.
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