Maternal Measles Antibodies and Their Influence on All-cause Mortality Following Measles Vaccination: An Alternative to Measure Very Low Maternal Antibody Levels

Effect of early two-dose measles vaccination on childhood mortality and modification by maternal measles antibody in Guinea-Bissau, West Africa: A single-centre open-label randomised controlled trial

BACKGROUND

Early 2-dose measles vaccine (MV) at 4 and 9 months of age vs. the WHO strategy of MV at 9 months of age reduced all-cause child mortality in a previous trial. We aimed to test two hypotheses: 1) a 2-dose strategy reduces child mortality between 4 and 60 months of age by 30%; 2) receiving early MV at 4 months in the presence versus absence of maternal measles antibodies (MatAb) reduces child mortality by 35%.

METHODS

Single-centre open-label community-based randomised controlled trial in Guinea-Bissau, with 2:1 block-randomisation by sex to a 2-dose (4 + 9 months) vs. 1-dose (9 months) MV strategy. Healthy children were eligible 4 weeks after the 3rd diphtheria-tetanus-pertussis-containing vaccine. Before randomisation a blood sample was collected to determine MatAb level. The primary outcome was all-cause mortality. Hazard ratios (HR) were derived from Cox regression in the per protocol population. We tested for interactions with national campaigns with oral polio vaccine (C-OPV). Trial registration: NCT01486355.

FINDINGS

Between August 2011-April 17th 2015, 6,636 children were enroled, 6,598[n_2-dose=4,397; n_1-dose=2,201] were included in the analysis of the primary outcome, The HR(2-dose/1-dose) between 4 and 60 months was 1.38 (95%CI: 0.92-2.06) [deaths: n_2-dose=90; n_1-dose=33]. Before the 9-month MV and the HR(1-dose/no dose) was 0.94 (0.45-1.96) [deaths: n_2-dose=21; n_1-dose=11]. The HR(2-dose/1-dose) was 0.81 (0.29-2.22) for children, who received no C-OPV [deaths/children: n_2-dose=10/2,801; n_1-dose=6/1,365], and 4.73 (1.44-15.6) for children, who received C-OPV before and after enrolment (p for interaction=0.027) [deaths/children: n_2-dose=27/1,602; n_1-dose=3/837]. In the 2-dose group receiving early MV at 4 months, mortality was 50% (20-68%) lower for those vaccinated in the presence of MatAb vs. the absence of MatAb [deaths/children: n_MatAb=51/3,132; n_noMatAb=31/1,028].

INTERPRETATION

The main result contrasts with previous findings but may, though based on a small number of events, be explained by frequent OPV campaigns that reduced the mortality rate, but apparently interacted negatively with early MV. The beneficial non-specific effects of MV in the presence of MatAb should be investigated further.

FUNDING

ERC, Danish National Research Foundation, the Danish Council for Development Research, Ministry of Foreign Affairs, Novo Nordisk Foundation, European Union and the Lundbeck Foundation.

Measles, mumps, rubella prevention: how can we do better?

INTRODUCTION

Measles, mumps, and rubella incidence decreased drastically following vaccination programs' implementation. However, measles and mumps' resurgence was recently reported, outbreaks still occur, and challenges remain to control these diseases.

AREAS COVERED

This qualitative narrative review provides an objective appraisal of the literature regarding current challenges in controlling measles, mumps, rubella infections, and interventions to address them.

EXPERT OPINION

While vaccines against measles, mumps, and rubella (including trivalent vaccines) are widely used and effective, challenges to control these diseases are mainly related to insufficient immunization coverage and changing vaccination needs owing to new global environment (e.g. traveling, migration, population density). By understanding disease transmission peculiarities by setting, initiatives are needed to optimize vaccination policies and increase vaccination coverage, which was further negatively impacted by COVID-19 pandemic. Also, awareness of the potential severity of infections and the role of vaccines should increase. Reminder systems, vaccination of disadvantaged, high-risk and difficult-to-reach populations, accessibility of vaccination, healthcare infrastructure, and vaccination services management should improve. Outbreak preparedness should be strengthened, including implementation of high-quality surveillance systems to monitor epidemiology. While the main focus should be on these public health initiatives to increase vaccination coverage, slightly more benefits could come from evolution of current vaccines.