Efecto de la administración previa de la vacuna DPT en la respuesta de anticuerpos anti- PRP: en niños inmunizados con la vacuna PRP-T: informe preliminar / Effect of prior administration of DPT vaccine in the response of anti-PRP antibody: in children immunized with the vaccine PRP-T: preliminary report

El objetivo del estudio fue evaluar los efectos de la vacunación DPT dos semanas antes de la primera dosis de la administración de la vacuna PRP-T, sobre la respuesta de anticuerpos anti-PRP en lactantes vacunados a los 2, 4 y 6 meses de edad. Luego de la obtención del consentimiento informado escrito, 141 niños de 2 meses de edad fueron distribuidos al azar en uno de tres grupos, para ser vacunados a los 2, 4 y 6 meses de edad respectivamente. El Grupo A incluyó vacunados con DPT dos semanas previas a la primeras dosis de PRP-T; el Grupo B a aquellos vacunados con PRP-T y DPT simultáneamente, en sitios separados; y el Grupo C a los vacunados con PRP-T, dos semanas previas a la primera dosis de DPT. La segunda y la tercera dosis de ambas vacunas se administraron simultáneamente en los tres grupos. Se tomaron muestras de sangre a los 2,4, 6 y 7 meses de vida. Los sueros fueron conservados a menos de 20º centígrados hasta su envío a la Universidad de Vanderbilt, donde fueron procesados en ciego y en paralelo por el método de ELISA. Los datos serológicos fueron transformados logarítmicamente para su análisis, reportándose su antilogaritmo. Para el análisis estadístico se aplicó la prueba ANOVA, un valor p<0,05 fue considerado estadísticamente significativo. Los títulos de anticuerpos posteriores a la primera dosis en los grupos A, B y C fueron respectivamente de 6,3, 1,9 y 1,05 mcg/ml; para la segunda dosis se obtuvieron títulos de 14.6; 9,20 y 8,93 mcg/ml para cada grupo y para la tercera, los resultados fueron respectivamente de 25,68; 17,38 y 26,47 mcg/ml. El análisis de varianza demostró que después de la primera dosis el grupo A inmunizado previamente con DTP obtuvo títulos de anticuerpos significativamente más altos que los otros dos que dicha diferencia se mantuvo después de la segunda inyección, (p<0,0001 y 0,04 respectivamente) sin embargo no hubo significación estadística posterior a la aplicación de la tercera dosis (p=0,23).

Safety, immunogenicity and antibody persistence of an inactivated hepatitis A vaccine in 4 to 15 year old children.

Among 277 healthy Venezuelan children, aged between 4 and 15 years, who were screened for hepatitis A virus (HAV) antibodies, 118 seronegative children were enrolled in an open study. Each child received one dose of the Pasteur Mérieux Connaught inactivated hepatitis A vaccine (AVAXIM¿trade mark omitted¿, 160 antigen units), followed by a booster dose 24 weeks later. All seronegative subjects seroconverted 2 weeks after immunisation (antibody titres greater, similar20 mIU/ml), and antibody titres were still over greater, similar20 mIU/ml after 24 weeks, at the moment of the booster dose. The anti-HAV antibody geometric mean titre (GMT), as measured by a modified radio-immunoassay (HAVAB(R), Abbott Laboratories, North Chicago, IL, USA), was 73.7 mIU/ml, 2 weeks after the first dose. Four weeks after the booster, the GMT value reached 6999 mIU/ml, representing a 29.6-fold rise from pre-booster levels. One year after the booster dose, the GMT value was 1673 mIU/ml in the 92 subjects who provided blood samples at this time, all of whom were still seroconverted ( greater, similar20 mIU/ml). No serious adverse event related to the vaccination occurred during the study. No immediate systemic reaction occurred. Local reactions were reported by 9.3% of subjects who received the primary injection and 5.5% of those given the booster dose. The systemic reactions were mainly fever and myalgia reported over the 7 days following the injection by 3.4% of subjects after the first dose and 5.5% of subjects after the booster dose. A clinically significant elevation of serum transaminase from pre-immunisation levels was noted in one subject (AST level 2.2 times the upper normal limit) 2 weeks after the first injection, although this was not associated with any clinical signs of impaired liver function. This trial demonstrated that AVAXIM¿trade mark omitted¿ containing 160 antigen units is safe and highly immunogenic in healthy children aged between 4 and 15 years, and could be included in the childhood vaccination schedule to control infection in areas endemic for hepatitis A.

Enhanced antibody response in Venezuelan infants immunized with Haemophilus influenzae type b-tetanus toxoid conjugate vaccine.

The safety and immunogenicity of primary immunization at 2, 4 and 6 months of age with Haemophilus influenzae type b capsular polysaccharide conjugated to tetanus toxoid (PRP-T; Act-HIB) were evaluated in infants in Valencia, Venezuela. In order better to assess reactions to PRP-T, subjects received their initial PRP-T vaccine a mean of 6.5 days after their initial diphtheria-tetanus-pertussis (DTP) vaccine. The PRP-T vaccine was well tolerated. Serum was obtained at ages 2 and 7 months (before the first and 1 month after the third PRP-T dose). Antibody responses were compared with those from Nashville infants who had received PRP-T and DTP simultaneously in a previous trial. The preimmunization titers in the Venezuelan and Nashville infants did not differ. The geometric mean postimmunization titer in the Venezuelan infants was 37.9 micrograms/ml, as compared with 3.63 micrograms/ml in the Nashville infants (P < 0.00001). Possible explanations for the exceptional antibody response of these Venezuelan infants to PRP-T include carrier priming caused by prior DTP immunization, synergy associated with the specific DTP vaccine used, preimmunization immunologic experience that differed from their United States counterparts and genetic differences that altered response to the vaccines. Further studies are proposed to evaluate these possibilities.

[Serum cationic trypsinogen: marker of exocrine pancreatic dysfunction in children with protein-calorie malnutrition]. / Tripsinógeno catiónico sérico: indicador de disfunción pancreática exocrina en niños con malnutrición proteíno-calórica.

Serum cationic trypsinogen, a non invasive, sensitive test to evaluate the exocrine pancreatic function was measured by radioimmunoassay in 31 children with different degrees of protein-calorie malnutrition (mild, moderate, severe) in whom mean serum albumin values were 3.7 +/- 0.7 g%; 3.1 +/- 0.9 g%; 2.3 +/- 0.4 g%, respectively and in a control group of 20 well-nourished children with mean serum albumin values of 3.9 +/- 0.7 g%. Mean serum trypsinogen levels were significantly elevated in children with malnutrition (mild: 28.5 +/- 2.4 ng/ml, moderate: 31.86 +/- 3.4 ng/ml, and severe: 36.52 +/- 7.8 ng/ml) compared with the mean values in the control group (17.7 +/- 2 ng/ml). (p < 0.001). We conclude that our results suggest evidence of a pancreatic damage in malnourished children and this disfunction increases according to the degree of malnutrition, allowing to be detected with this simple test even when the patient does not present qualitative steatorrhea.