Inequalities in childhood pneumococcal conjugate vaccine uptake in England before and after the change from a 2 + 1 to 1 + 1 schedule: a longitudinal study.

Background: Introducing pneumococcal conjugate vaccines (PCVs) into England's childhood immunisation schedule has reduced pneumococcal disease. Nonetheless, pneumococcal disease burden persists, including in young children. In January 2020, England replaced the '2 + 1' PCV schedule (two primary doses at 8 and 16 weeks, booster dose at 12 months) with a '1 + 1' PCV schedule (primary dose at 12 weeks, booster dose at 12 months). Although immunogenicity studies suggested comparable protection, the reduced-dose schedule increases reliance on timely booster uptake. We examined national trends in PCV uptake before and after the schedule change and quantified inequalities by deprivation. Methods: We analysed quarterly vaccine uptake data for 2013-2025 from COVER (Cover of Vaccination Evaluated Rapidly) for upper-tier local authorities in England, linked to 2019 Index of Multiple Deprivation quintiles. We examined booster gaps-difference between primary coverage at 12 months and booster coverage at 24 months. We estimated susceptibility to vaccine-type invasive pneumococcal disease by birth cohort and quarter, combining observed PCV uptake with published vaccine effectiveness estimates. Findings: Booster retention deteriorated following the schedule change; mean booster gaps increased from 2.32% (2 + 1 period) to 4.79% (1 + 1 period). Inequalities widened, with differences between least and most deprived quintiles increasing from 2-3% to 4-6%. Estimated susceptibility showed marked geographical variation, with higher burden in deprived areas. Interpretation: The success of the 1 + 1 schedule depends on maintaining equitable, high booster uptake. Declining booster retention and widening inequalities risk undermining impact, highlighting the need for targeted support and strengthened follow-up systems. Funding: No specific funding.