Long-term immunity against yellow fever in children vaccinated during infancy: a longitudinal cohort study

Autor: Domingo, Cristina, Fraissinet, Juliane, Ansah, Patrick, Kelly, Corey, Bhat, Niranjan, Sow, Samba, Mejía, José
Přispěvatelé: Centre for Biological Threats and Special Pathogens [Berlin] (ZBS), Robert Koch Institute [Berlin] (RKI), Navrongo Health Research Centre [Navrongo, Ghana] (NHRC), PATH [Seattle], Institut National de Recherche en Santé Publique [Bamako] (INRSP), Centre de Physiopathologie Toulouse Purpan (CPTP), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Centre Hospitalier Universitaire de Toulouse (CHU Toulouse), Pistre, Karine
Jazyk: angličtina
Rok vydání: 2019
Předmět:
Zdroj: The Lancet Infectious Diseases
The Lancet Infectious Diseases, 2019, 19 (12), pp.1363-1370. ⟨10.1016/S1473-3099(19)30323-8⟩
ISSN: 1473-3099
1474-4457
DOI: 10.1016/S1473-3099(19)30323-8⟩
Popis: International audience; BackgroundA single dose of vaccine against yellow fever is routinely administered to infants aged 9–12 months under the Expanded Programme on Immunization, but the long-term outcome of vaccination in this age group is unknown. We aimed to evaluate the long-term persistence of neutralising antibodies to yellow fever virus following routine vaccination in infancy.MethodsWe did a longitudinal cohort study, using a microneutralisation assay to measure protective antibodies against yellow fever in Malian and Ghanaian children vaccinated around age 9 months and followed up for 4·5 years (Mali), or 2·3 and 6·0 years (Ghana). Healthy children with available day-0 sera, a complete follow-up history, and no record of yellow fever revaccination were included; children seropositive for yellow fever at baseline were excluded. We standardised antibody concentrations with reference to the yellow fever WHO International Standard.FindingsWe included 587 Malian and 436 Ghanaian children vaccinated between June 5, 2009, and Dec 26, 2012. In the Malian group, 296 (50·4%, 95% CI 46·4–54·5) were seropositive (antibody concentration ≥0·5 IU/mL) 4·5 years after vaccination. Among the Ghanaian children, 121 (27·8%, 23·5–32·0) were seropositive after 2·3 years. These results show a large decrease from the proportions of seropositive infants 28 days after vaccination, 96·7% in Mali and 72·7% in Ghana, reported by a previous study of both study populations. The number of seropositive children increased to 188 (43·1%, 95% CI 38·5–47·8) in the Ghanaian group 6·0 years after vaccination, but this result might be confounded by unrecorded revaccination or natural infection with wild yellow fever virus during a 2011–12 outbreak in northern Ghana.InterpretationRapid waning of immunity during the early years after vaccination of 9-month-old infants argues for a revision of the single-dose recommendation for this target population in endemic countries. The short duration of immunity in many vaccinees suggests that booster vaccination is necessary to meet the 80% population immunity threshold for prevention of yellow fever outbreaks.
Databáze: OpenAIRE
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