Vaccine-preventable diseases and their impact on Latin American children

Abstract

A joint meeting of the Latin American Society of Pediatric Infectious Diseases, the Dominican Society of Pediatrics and the Dominican Society of Vaccinology was held in the Dominican Republic. This report highlights the most relevant issues that were presented and discussed about vaccine-preventable diseases, their epidemiology and impact in Latin American children, the need to move forward and expand national immunization programs and the economical and political obstacles to introduce ‘new’ vaccines. These include those against Streptococcus pneumoniae, rotavirus, hepatitis A, varicella, Neisseria meningitidis, Bordetella pertussis, influenza and human papillomavirus, among others.

Keywords::

• children
• community-acquired pneumonia
• conference
• Latin America
• pediatric infectious diseases
• vaccine-preventable diseases
• vaccines

The XIV Conference of the Latin American (LA) Society of Pediatric Infectious Diseases (Sociedad Latinoamericana de Infectología Pediátrica [SLIPE]), the XLI Conference of the Dominican Society of Pediatrics, and the I Conference of the Dominican Society of Vaccinology, were held together in Punta Cana, Dominican Republic, from 25 to 28 May 2011. The scientific program included topics on general pediatric infectious diseases (PID); however, this report focuses on the most relevant discussed issues surrounding vaccine-preventable diseases.

This meeting was devoted to the memory of two distinguished and renowned PID experts, Calil Farhat and Hugo Paganini, who both passed away in 2010. Farhat (Brazil) was known as one of the pioneers of PID in LA. He was an exceptional opinion leader, speaker, and a prominent author of books, textbook chapters, journal articles and abstracts. He trained many specialists in PID from Brazil and LA. His brilliant career included many honors, distinctions and awards in Brazil and internationally, including a diploma honor from the American Academy of Pediatrics [101]. Hugo Paganini, from the Hospital Nacional de Pediatría “Prof. Dr J P Garrahan” (Argentina), was a renowned clinician, researcher, speaker and trainer in PID in his country and abroad. His major interests and well recognized contributions were in the field of infectious diseases (ID) in children with cancer [1]. Recently, he co-led the second SLIPE consensus and guidelines on febrile neutropenia in children with cancer.

The two opening lectures were given by Marcos Espinal (Dominican Republic), from the Panamerican Health Organization, and María L Avila-Aguero, Minister of Health for Costa Rica. During the first lecture entitled ‘Impact of ID in the Americas’, Espinal referred to the burden and negative impact of ID in LA, particularly in children under 5 years of age. He emphasized the three main causes of death in this population: respiratory diseases (pneumonia and bronchiolitis), diarrhea (rotavirus, parasites and cholera) and vaccine-preventable diseases. During the lecture, ‘Vaccination programs as a social investment’ , Avila-Aguero emphasized the cost benefits of vaccine introduction in national immunization programs, quoting the examples of MMR, varicella and pneumococcus, and that vaccine introduction has resulted in an increase of 10–15 years in life-expectancy. She mentioned that for LA children two worlds exist in terms of vaccine equity: those with access to ‘new vaccines’ and the other group with poor access due to economic limitations. Also, vaccines should be considered as a human right and public health and collegiate organizations should make joint efforts to decrease this gap and delay of up to 6–12 years.

Argentinean researchers referred to their world-leading experience with the single-dose schedule of hepatitis A universal immunization program administered at 12 months of age. Since its start in 2005, the number of cases, hospitalizations, acute liver failure episodes, deaths and liver transplants has decreased significantly [2]. This experience could be extrapolated to other LA countries in which the two-dose schedule is not economically feasible.

Tina Tan (Children’s Memorial Hospital; Chicago, IL, USA) and other experts referred to the current epidemiology and impact of pertussis and the 2011 Advisory Committee on Immunization Practices (ACIP) updated Tdap vaccine recommendations [3]. Among these, Tdap is now recommended after 64 years of age. Recently, the ACIP released the provisional recommendations for Tdap use in pregnant women [102]. Among these, health care providers should administer Tdap during pregnancy, preferably during the third trimester or late second trimester. If not possible, mothers should then be immunized in the immediate postpartum period.

Updated recommendations of meningococcal vaccines against serogroups A, C, W135 and Y, the future of serogroup B vaccines and the current epidemiology of meningococcal disease in LA were discussed [4]. The major epidemiologic trends include the emergence of serogroups W135 and Y in some countries, such as Brazil and Argentina. Emphasis was placed on the fact that both the incidence and the circulating serogroups differ from country to country, and that vaccine recommendations should be individualized accordingly. Chacón-Cruz et al. presented preliminary results of a prospective multicenter study in Mexico on the epidemiology of pediatric meningococcal disease. During the first year of survey they found an increased incidence compared with their historical data [5].

The safety, effectiveness and impact of rotavirus vaccine introduction in the decrease of severe gastroenteritis, hospitalizations, and deaths in some LA countries was discussed, including Mexico, El Salvador, Brazil and Panama [6–9]. Despite the worldwide and local beneficial evidence, some LA countries have still not introduced it universally due to economical reasons, among others.

Jorge Quian (Centro Hospitalario Pereira Rossell; Montevideo, Uruguay) referred to the impact of the universal single-dose varicella vaccine introduction in his country at the end of 1999. Uruguay was the first LA country to introduce it in an official immunization program. By 2005, an 81 and 87% reduction of hospitalizations and outpatient visits were observed, respectively [10]. Similarly, Avila-Aguero mentioned that in Costa Rica, after universal vaccination with single-dose schedule since September 2007, in 2008–2010 a 75 and 83% reduction were documented in the general population, and in children younger than 5 years of age, respectively. Thus far, only these countries have introduced universal varicella vaccination in LA.

Keith Klugman (Emory University, Atlanta, USA) referred to the predisposing role of seasonal and pandemic influenza in bacterial pneumonia, predominantly pneumococcal. Among deceased patients during the 2009 H1N1 pandemic, pneumococcus was the most common pathogen causing secondary infections [11]. These findings strengthen the importance of annual influenza vaccination. Recent research by the same group suggests that after universal pneumococcal conjugate vaccine (PCV7) introduction for US infants, states that had greater and earlier PCV7 coverage had significantly fewer pediatric influenza-associated pneumonia hospitalizations during the following influenza epidemic seasons. These data suggests that PCV7 decreases influenza-associated hospitalization rates [12].

The importance of pneumococcal disease surveillance before and after universal conjugate vaccines introduction, including serotype distribution, was highlighted (i.e., serotype 19A emergence). In March 1998, Uruguay was the first LA country to introduce PCV7 universally. The impact of this intervention was recently published [13]. The preliminary results of COMPAS, evaluating the efficacy of the ten-valent pneumococcal nontypeable Haemophilus influenzae protein-D conjugate vaccine against community-acquired pneumonia (CAP) in LA were presented during SLIPE and thereafter in oral symposiums and poster presentations by Sáez-Llorens et al.[14]. In this study, 23,738 children were included in the intent-to-treat cohort, of which 20,496 were included in the according-to-protocol (ATP) cohort for the CAP efficacy analysis. Vaccine efficacy against the first bacterial CAP episode was 22% (p = 0.002) in the ATP cohort. Vaccine efficacy was also documented against WHO/defined chest radiograph-alveolar consolidated-CAP, CXR-CAP and Suspected/CAP with consistent results seen between the ATP and intention-to-treat cohorts.

The symposium on the changes and recommendations of polio vaccination for the Americas discussed the experiences of Mexico, Costa Rica and Brazil. The eradication of paralytic polio from the Americas after universal introduction of oral polio vaccine has been one of the most important achievements in public health in LA. Currently, vaccine-associated paralytic polio is a concern, as occurred in the last two decades in Dominican Republic, Haiti, Mexico and Colombia. A review on the topic has recently been published in this journal [15].

The epidemiology, the economical impact and the future prevention by vaccination of dengue in LA were discussed. Outbreaks have been reported in all Central America and the Caribbean during the last two decades, where it is endemic, and has extended to Mexico, Paraguay and Argentina [16,17]. In the Americas is estimated to cost US$2.1 billion/year on average. Clinical trials testing dengue vaccines in LA infants and children have been completed and others are underway.

Additionally, various symposia scored the epidemiology, disease burden, lessons learned, and importance and challenges of vaccine introduction during H1N1 epidemic in LA. Data from the recent cholera outbreak in Haiti and Dominican Republic, its prevention and future aspects of vaccination were analyzed. Other vaccine topics included: vaccination of premature infants, the future of group B streptococcal vaccines, ethical challenges in vaccine introduction and the economical and political obstacles to vaccine introduction.

Conclusion

Vaccination still is the most important preventive and cost-effective intervention to decrease morbidity and mortality rates in children. In the era of new vaccines against common and serious diseases, LA countries should make great efforts to document the epidemiology of these diseases prior to and after the introduction of vaccines. It is important to document individual country experiences and diffuse their knowledge, as these interventions should help other countries in their decision making. The introduction of these vaccines in LA should be prioritized according to the epidemiology, disease burden, mortality rates and economic costs, among others.

Financial & competing interests’ disclosure

None of the authors are employees of any pharmaceutical company. R Ulloa-Gutierrez has served as an invited speaker for Sanofi Pasteur, GlaxoSmithKline, Wyeth, Pfizer and Merck; on advisory boards for Sanofi Pasteur, GlaxoSmithKline and Wyeth; and as chairman and cochairman for Sanofi Pasteur and GlaxoSmithKline. G Miño has served on advisory boards for GlaxoSmithKline and Merck; and as a cochairman for Wyeth, but has no other conflicts of interest to declare. C Odio has served as invited speaker for Sanofi Pasteur and Merck, but has no conflicts of interest to declare. ML Avila-Aguero has no conflicts of interest to declare during the last 5 years. J Brea has served as an invited speaker for Sanofi Pasteur, GlaxoSmithKline, Wyeth, Pfizer and Merck; on advisory boards for Sanofi Pasteur and GlaxoSmithKline. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.