Immunogenicity of RV1 and RV5 vaccines administered in standard and interchangeable mixed schedules: a randomized, double-blind, non-inferiority clinical trial in Mexican infants

IntroductionRotavirus-associated diarrheal diseases significantly burden healthcare systems, particularly affecting infants under five years. Both Rotarix™ (RV1) and RotaTeq™ (RV5) vaccines have been effective but have distinct application schedules and limited interchangeability data. This study aims to provide evidence on the immunogenicity, reactogenicity, and safety of mixed RV1-RV5 schedules compared to their standard counterparts.MethodsThis randomized, double-blind study evaluated the non-inferiority in terms of immunogenicity of mixed rotavirus vaccine schedules compared to standard RV1 and RV5 schedules in a cohort of 1,498 healthy infants aged 6 to 10 weeks. Participants were randomly assigned to one of seven groups receiving various combinations of RV1, and RV5. Standard RV1 and RV5 schedules served as controls of immunogenicity, reactogenicity, and safety analysis. IgA antibody levels were measured from blood samples collected before the first dose and one month after the third dose. Non-inferiority was concluded if the reduction in seroresponse rate in the mixed schemes, compared to the standard highest responding scheme, did not exceed the non-inferiority margin of −0.10. Reactogenicity traits and adverse events were monitored for 30 days after each vaccination and analyzed on the entire cohort.ResultsOut of the initial cohort, 1,365 infants completed the study. Immunogenicity analysis included 1,014 infants, considering IgA antibody titers ≥20 U/mL as seropositive. Mixed vaccine schedules demonstrated non-inferiority to standard schedules, with no significant differences in immunogenic response. Safety profiles were comparable across all groups, with no increased incidence of serious adverse events or intussusception.ConclusionThe study confirms that mixed rotavirus vaccine schedules are non-inferior to standard RV1 and RV5 regimens in terms of immunogenicity and safety. This finding supports the flexibility of rotavirus vaccination strategies, particularly in contexts of vaccine shortage or logistic constraints. These results contribute to the global effort to optimize rotavirus vaccination programs for broader and more effective pediatric coverage.Clinical trial registration: ClinicalTrials.gov, NCT02193061

A multi-country study of intussusception in children under 2 years of age in Latin America: analysis of prospective surveillance data

BACKGROUND: Intussusception (IS) is a form of acute intestinal obstruction that occurs mainly in infants and is usually of unknown cause. An association between IS and the first licensed rotavirus vaccine, a reassortant-tetravalent, rhesus-based rotavirus vaccine (RRV-TV), led to the withdrawal of the vaccine. New rotavirus vaccines have now been developed and extensively studied for their potential association with IS. This study aimed to describe the epidemiology and to estimate the incidence of IS in Latin American infants prior to new vaccine introduction. METHODS: Children under 2 years of age representing potential IS cases were enrolled in 16 centers in 11 Latin American countries from January 2003 to May 2005. IS cases were classified as definite, probable, possible or suspected as stated on the Brighton Collaboration Working Group guidelines. RESULTS: From 517 potential cases identified, 476 (92%) cases were classified as definite, 21 probable, 10 possible and 10 suspected for intussusception. Among the 476 definite IS cases, the median age at presentation was 6.4 months with 89% of cases aged <1 year. The male to female ratio was 1.5:1. The incidence of definite IS per 100,000 subject-years ranged from 1.9 in Brazil to 62.4 in Argentina for children <2 years of age, and from 3.8 in Brazil to 105.3 in Argentina for children aged <1 year. Median hospital stay was 4 days with a high prevalence of surgery as the primary treatment (65%). Most cases (88%) made a complete recovery, but 13 (3%) died. No clear seasonal pattern of IS cases emerged. CONCLUSIONS: This study describes the epidemiology and estimates the incidence of IS in Latin American infants prior to the introduction of new rotavirus vaccines. The incidence of IS was found to vary between different countries, as observed in previous studies. TRIAL REGISTRATION: Clinical study identifier 999910/204 (SERO-EPI-IS-204

Hacia la erradicación de la poliomielitis: logros y retos en México

Desde la implementación de las estrategias globales de erradicación, la incidencia de parálisis poliomielítica ha disminuido dramáticamente. Cuatro estrategias han contribuido notablemente: a) Altas coberturas de inmunización con vacuna oral de polio (VOP), b) Inmunización suplementaria durante los Días Nacionales de Vacunación, c) Vigilancia epidemiológica efectiva de casos de parálisis flácida aguda (PFA), y d) Bloqueos vacunales en zonas de alto riesgo. Sólo quedan tres países polioendémicos, no obstante, cualquier país corre el riesgo potencial de importación del virus de algunas de estas áreas, de la liberación accidental del virus resguardado en laboratorios de diagnóstico clínico o investigación, o de la presencia de virus circulantes derivados de vacuna en el medio ambiente. Este documento pretende exponer los antecedentes históricos que hicieron posible la eliminación de la enfermedad en México, así como los retos para lograr un mundo libre de poliomielitis.Since the strategies to eradicate polio were implemented, the incidence of paralytic polio has dropped dramatically. Four main strategies have greatly contributed: a) High immunization coverage rate with oral polio vaccine (OPV), b) Supplementary immunization activities during the National Immunizations Days c) An effective epidemiological surveillance system for acute flaccid paralysis (AFP) and d) Intensified immunization activities in high risk areas. Three countries remain polio endemic, nevertheless, any country has a potential risk of the virus importation from one of these endemic areas; an accidental release of poliovirus from a research or clinical laboratory, or from having a circulating vaccine-derived poliovirus in the environment. The present document aims to provide an historical background that made possible the disease elimination in Mexico. Moreover, we discuss the challenges that every country needs to face in order to achieve a polio-free world

Niveles de plomo en sangre y factores de exposición en niños del estado de Morelos, México

OBJETIVO: Evaluar los niveles de plomo en sangre de niños morelenses y sus factores de exposición. MATERIAL Y MÉTODOS: Estudio transversal para analizar, por voltametría anódica, los niveles de plomo en sangre de 232 niños de 1 a 12 años de edad, que acudieron de junio a octubre de 1996 al Hospital del Niño Morelense de Cuernavaca, Morelos, México. Los factores de exposición se indagaron por cuestionario. El valor de concentración de plomo se transformó al logaritmo natural; se estimó la razón de momios para algunos factores de exposición que se incorporaron a un modelo de ANOVA. RESULTADOS: Se reclutaron 232 niños (50% mujeres); 73% residentes en Cuernavaca. La media geométrica de plomo en sangre fue 6.7 µg/dl; 29.7% rebasaron los 10 µg/dl; 66% tenían antecedente de cocinar alimentos en barro vidriado; 36% de almacenar alimentos, y 19%, consumo de líquidos en ese material. CONCLUSIONES: Los niveles encontrados son similares a los reportados en otras poblaciones pediátricas mexicanas en los últimos años. Entre los principales factores de exposición destacan el uso de barro vidriado para consumo de alimentos o líquidos y la intensidad del tráfico donde viven. Este es el primer estudio que documenta los niveles de plomo en sangre en población infantil de Morelos, México, y sus resultados son punto de partida para acciones futuras de control y prevención

Resurgimiento de enfermedad hemorrágica del recién nacido: Implicaciones para su prevención

Objetivo. Describir la experiencia con enfermedad hemorrágica del recién nacido en un hospital pediátrico del tercer nivel de atención. Material y métodos. Estudio retrospectivo efectuado en el Hospital del Niño Morelense de la ciudad de Cuernavaca, estado de Morelos, México, durante el periodo 1997-2000, con una muestra de 46 neonatos, afectados de enfermedad hemorrágica del recién nacido (EHRN), referidos de poblaciones de la periferia del estado. Resultados. De los pacientes, 91% presentó la forma tardía grave de EHRN. El 52% de los partos fueron atendidos por médico y 48% por parteras. Se desconoce aplicación de vitamina K en 61%, en 35% no fue aplicada y en 4% sí se aplicó. La mayoría presentó sintomatología severa secundaria a hemorragia intracraneana. Hubo defunción en 11% y secuelas severas en 41%. Conclusiones. La EHRN es un problema frecuente en el estado de Morelos y, por ello, se requiere analizar los programas de salud reproductiva e intensificar la capacitación de médicos y enfermeras sobre la prevención de ésta mediante el uso de vitamina K