Haemophilus influenzae Type b Vaccine Failure in Portugal: A Nationwide Multicenter Pediatric Survey

Marques, José Gonçalo; Inácio Cunha, Florbela Maria; Bajanca-Lavado, Maria Paula; Portuguese Study Group on Haemophilus influenzae Invasive Disease in Children

http://hdl.handle.net/10400.18/8675

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Authors

Marques, José Gonçalo

Inácio Cunha, Florbela Maria

Bajanca-Lavado, Maria Paula

Portuguese Study Group on Haemophilus influenzae Invasive Disease in Children

Abstract(s)

Background: Despite the high effectiveness of the Haemophilus influenzae type b (Hib) vaccine in preventing invasive disease (ID) in children, Hib vaccine failures (VFs) cases may still occur. This study aimed to characterize the Hib-VF cases in Portugal in a 12-year period and trying to identify the possible associated risk factors. Methods: Prospective descriptive nationwide surveillance study. Bacteriologic and molecular studies were performed at the same Reference Laboratory. Clinical data were collected by the referring pediatrician. Results: Hib was identified in 41 children with ID and 26 (63%) were considered VF. Nineteen (73%) cases occurred in children less than 5 years old; 12 (46%) occurred before the Hib vaccine booster dose at 18 months of age. Comparing the first and the last 6-year periods of the study, the incidence rate of Hib, VF and total H. influenzae (Hi) ID significantly raised ( P < 0.05). VF cases corresponded, respectively, to 13.5% (7/52) and 22% (19/88) of total Hi-ID cases ( P = 0.232). Two children died due to epiglottitis and 1 acquired sensorineural hearing loss. Only 1 child had an inborn error of immunity. The immunologic workup performed in 9 children revealed no significant abnormalities. All 25 Hib-VF strains analyzed belonged to the same clonal complex 6. Conclusions: In Portugal, more than 95% of children are vaccinated against Hib, but severe Hib-ID cases still occur. No predisposing factors were clearly identified to justify the increased number of VF in recent years. Along with continued Hi-ID surveillance, Hib colonization and serologic studies should be implemented.

Description

Portuguese Study Group on Haemophilus influenzae Invasive Disease in Children: Celia Bettencourt, Arminda Maria Jorge, Maria Conceição Faria, Carla Zilhão, Laura Marques, Conceição Casanova, Cristiana Pereira, Fernando Fonseca, Cláudia Monteiro, Mariana Bettencourt, Diana Moreira, Fernanda Rodrigues, Henrique Oliveira, Catarina Sousa, Graciete Pinheiro, Sara Diogo Santos, Adília Vicente, Tiago Milheiro, Margarida Pinto, Graça Seves, Rosa Bento, M ª João Virtuoso, Rita Fonseca, Maria Dinah Carvalho, Luís Lito, Carla Cruz, Adriana Coutinho, Paula Correia, Luísa Sancho, Elzara Aliyeva, Cristina Freitas, Nuno Canhoto, Ana Filipa Nunes, Ana Maria Queiroz, José Diogo, Maria Manuel Flores, Paula Reis, Elmano Ramalheira, Maria Manuel Zarcos, Sofia Lima, Susana Castilho, Catarina Lacerda, Luísa Teixeira, Ana Maria Jesus, Sofia Maia Aroso, Margarida Tavares, Bonito Vitor, Angélica Ramos, Manuela Costa Alves, Isabel Cunha, Alberta Faustino, Álvaro Sousa, Margarida Rodrigues, Idalina Maciel, Sandra Vieira, Jorge Rodrigues, Elisabete Santos, Alexandra Costa, Filomena Martins, Carlos Escobar, Pedro Flores, Maria Favila Menezes, João Calado Nunes, Ana Neto, Marina Soares, Rita Mouro Pinto, Diana Almeida, Isabel Brito, Hermínia Costa, Fátima Silva, Joana Cardoso, Magalys Pereira, Luís Gonçalves, João Tavares, Sofia Botelho Moniz, Eurico Jorge Gaspar, Joana Carvalho, Ana Paula Castro, Álvaro Sousa, Catarina Francisco, João Farela Neves, Paulo Paixão.