Early estimates of the effectiveness of the 2011/12 influenza vaccine in the population targeted for vaccination in Spain, 25 December 2011 to 19 February 2012.

We present early estimates of influenza vaccine effectiveness (VE) in the population targeted for vaccination, during 25 December 2011 to 19 February 2012. The adjusted VE was 55% (95% CI: 3 to 79) against any type of influenza virus and 54% (95% CI: 1 to 79) against influenza A(H3N2) virus. This suggests a moderate protective effect of the vaccine in the targeted population in a late influenza epidemic with limited match between vaccine and circulating strains.

Reduction in morbidity and mortality from childhood diarrhoeal disease after species A rotavirus vaccine introduction in Latin America : a review

Countries in Latin America were among the first to implement routine vaccination against species A rotavirus (RVA). We evaluate data from Latin America on reductions in gastroenteritis and RVA disease burden following the introduction of RVA vaccine. Published literature was reviewed to identify case-control studies of vaccine effectiveness and population-based studies examining longitudinal trends of diarrhoeal disease reduction after RVA vaccine introduction in Latin American countries. RVA vaccine effectiveness and impact on gastroenteritis mortality and hospitalization rates and RVA hospitalization rates are described. Among middle-income Latin American countries with published data (Mexico, Brazil, El Salvador and Panama), RVA vaccine contributed to a gastroenteritis-associated mortality reduction of 22-41%, a gastroenteritis-associated hospitalization reduction of 17-51% and a RVA hospitalization reduction of 59-81% among children younger than five years of age. In Brazil and El Salvador, case-control studies demonstrated that a full RVA vaccination schedule was 76-85% effective against RVA hospitalization; a lower effectiveness of 46% was seen in Nicaragua, the only low-income country with available data. A growing body of literature offers convincing evidence of "real world" vaccine program successes in Latin American settings, which may be expanded as more countries in the region include RVA vaccine in their immunization programs.

Induction and maintenance of protective CD8+ T cells against malaria liver stages: implications for vaccine development

CD8+ T cells against malaria liver stages represent a major protective immune mechanism against infection. Following induction in the peripheral lymph nodes by dendritic cells (DCs), these CD8+ T cells migrate to the liver and eliminate parasite infected hepatocytes. The processing and presentation of sporozoite antigen requires TAP mediated transport of major histocompatibility complex class I epitopes to the endoplasmic reticulum. Importantly, in DCs this process is also dependent on endosome-mediated cross presentation while this mechanism is not required for epitope presentation on hepatocytes. Protective CD8+ T cell responses are strongly dependent on the presence of CD4+ T cells and the capacity of sporozoite antigen to persist for a prolonged period of time. While human trials with subunit vaccines capable of inducing antibodies and CD4+ T cell responses have yielded encouraging results, an effective anti-malaria vaccine will likely require vaccine constructs designed to induce protective CD8+ T cells against malaria liver stages.

Platform for Plasmodium vivax vaccine discovery and development

Plasmodium vivax is the most prevalent malaria parasite on the American continent. It generates a global burden of 80-100 million cases annually and represents a tremendous public health problem, particularly in the American and Asian continents. A malaria vaccine would be considered the most cost-effective measure against this vector-borne disease and it would contribute to a reduction in malaria cases and to eventual eradication. Although significant progress has been achieved in the search for Plasmodium falciparum antigens that could be used in a vaccine, limited progress has been made in the search for P. vivax components that might be eligible for vaccine development. This is primarily due to the lack of in vitro cultures to serve as an antigen source and to inadequate funding. While the most advanced P. falciparum vaccine candidate is currently being tested in Phase III trials in Africa, the most advanced P. vivax candidates have only advanced to Phase I trials. Herein, we describe the overall strategy and progress in P. vivax vaccine research, from antigen discovery to preclinical and clinical development and we discuss the regional potential of Latin America to develop a comprehensive platform for vaccine development.

Oral live attenuated human rotavirus vaccine (RotarixTM) offers sustained high protection against severe G9P[8] rotavirus gastroenteritis during the first two years of life in Brazilian children

In a large Phase III trial conducted in 10 Latin American countries, the safety and efficacy of the live attenuated monovalent rotavirus vaccine RIX4414 was evaluated in 15,183 healthy infants followed up during the first two years of life. Belém was the only site in Brazil included in this multicentre trial. The study in Belém included a subset of 653 infants who were followed up until 24 months of age for protection against severe rotavirus gastroenteritis. These subjects were randomly assigned in a 1:1 ratio to receive two doses of vaccine (n = 328) or two doses of placebo (n = 325) at approximately two and four months of age. Of the 653 enrolled infants, 23 dropped out during the study period. For the combined two-year period, the efficacy of RIX4414 was 72.3% [95% confidence interval (CI) 37.5-89.1%] against severe rotavirus-related gastroenteritis, reaching a protection rate of 81.8% (95% CI 36.4-96.6%) against circulating wild-type G9 rotavirus strains. It is concluded that two doses of RIX4414 are highly efficacious against severe rotavirus gastroenteritis in Belém during the first two years of life and provide high protection against the worldwide emergence and spread of G9P[8] strains.

Comparison of adverse events following immunization with pandemic influenza A (H1N1)pdm09 vaccine with or without adjuvant among health professionals in Rio de Janeiro, Brazil

A vaccination campaign against pandemic influenza A (H1N1)pdm09 was held in Brazil in March 2010, using two types of monovalent split virus vaccines: an AS03-adjuvanted vaccine and a non-adjuvanted vaccine. We compared the reactogenicity of the vaccines in health professionals from a Clinical Research Institute in Rio de Janeiro, Brazil and there were no serious adverse events following immunization (AEFI) among the 494 subjects evaluated. The prevalence of any AEFI was higher in the AS03-adjuvanted vaccine at 2 h and 24 h post-vaccination [preva-lence ratio (PR): 2.05, confidence interval (CI) 95%: 1.55-2.71, PR: 3.42, CI 95%: 2.62-4.48, respectively]; however, there was no difference between the vaccines in the assessments conducted at seven and 21 days post-vaccination. The group receiving the AS03 post-adjuvanted vaccine had a higher frequency of local reactions at 2 h (PR: 3.01, CI 95%: 2.12-4.29), 24 h (PR: 4.57, CI 95%: 3.29-6.37) and seven days (PR: 6.05, CI 95%: 2.98-12.28) post-vaccination. We concluded that the two types of vaccines caused no serious AEFI in the studied population and the adjuvanted vaccine was more reactogenic, particularly in the 24 h following vaccination. This behaviour must be confirmed and better characterised by longitudinal studies in the general population.

Brazilian hepatitis B vaccine: a six-year follow-up in adolescents

The protective anti-HBs titres were examined six-year post-immunisation with the Brazilian recombinant hepatitis B vaccine. After the primary vaccination, all adolescents (n = 89) responded with protective anti-HBs titres and had a geometric mean titre (GMT) of 4031.8 mIU/mL. In 2010, 94.5% maintained protective anti-HBs (> 10 mIU/mL) antibodies, with a GMT of 236.0 mIU/mL. A positive correlation was observed between the anti-HBs titres after the primary vaccination and the titres at the six-year follow-up (p < 0.01). Eleven subjects showed anti-HBs titres suggestive of a natural booster. Prostitution and tattoos/piercings were marginally associated with natural boosters in the multivariate analysis. This study showed the first data on anti-HBs persistence following the Brazilian hepatitis B vaccine in sexually active individuals and highlights its effectiveness in the medium term.

Immune response to the mumps component of the MMR vaccine in the routine of immunisation services in the Brazilian National Immunisation Program

A non-controlled longitudinal study was conducted to evaluate the combined vaccine against measles, mumps and rubella (MMR) immunogenicity in 150 children vaccinated in the routine of three health units in the city of Rio de Janeiro, Brazil, 2008-2009, without other vaccines administered during the period from 30 days before to 30 days after vaccination. A previous study conducted in Brazil in 2007, in 1,769 children ranging from 12-15 months of age vaccinated against yellow fever and MMR simultaneously or at intervals of 30 days or more between doses, had shown low seroconversion for mumps regardless of the interval between administration of the two vaccines. The current study showed 89.5% (95% confidence interval: 83.3; 94.0) seroconversion rate for mumps. All children seroconverted for measles and rubella. After revaccination, high antibody titres and seroconversion rates were achieved against mumps. The results of this study and others suggest that two MMR doses confer optimal immunoresponses for all three antigens and the possible need for additional doses should be studied taking into account not only serological, but also epidemiological data, as there is no serological correlate of protection for mumps.

Getting ready for malaria elimination: a check list of critical issues to consider

In recent years, a renewed interest in malaria elimination and eradication has emerged and seems to be rooting in the minds of the scientific community, public health specialists, funding bodies, policy makers and politicians. Malaria eradication will certainly benefit from improved and innovative tools; notwithstanding novel knowledge in fields ranging from basic science to mathematical modelling and health systems research. However, the elimination of malaria also encompasses a broad range of essential aspects that countries and other actors need to consider when thinking of embarking on such an adventure, including the implementation of innovative strategies, the ability to incorporate the most up-to-date evidence into policy, the integration of malaria into the broader health agenda, the strengthening of surveillance and health systems, capacity building, funding, advocacy and, very importantly, research. While in some cases this enthusiasm is clearly justified, some countries are still a long way from realistically advancing towards elimination. This paper attempts to provide guidance on all the necessary issues that should be considered when initiating a malaria elimination program.

The Duffy binding protein as a key target for a Plasmodium vivax vaccine: lessons from the Brazilian Amazon

Plasmodium vivax infects human erythrocytes through a major pathway that requires interaction between an apical parasite protein, the Duffy binding protein (PvDBP) and its receptor on reticulocytes, the Duffy antigen/receptor for chemokines (DARC). The importance of the interaction between PvDBP (region II, DBPII) and DARC to P. vivax infection has motivated our malaria research group at Oswaldo Cruz Foundation (state of Minas Gerais, Brazil) to conduct a number of immunoepidemiological studies to characterise the naturally acquired immunity to PvDBP in populations living in the Amazon rainforest. In this review, we provide an update on the immunology and molecular epidemiology of PvDBP in the Brazilian Amazon - an area of markedly unstable malaria transmission - and compare it with data from other parts of Latin America, as well as Asia and Oceania.

Oral bacillus Calmette-Guérin vaccine against tuberculosis: why not?

The bacillus Calmette-Guérin (BCG) vaccine is the only licensed vaccine for human use against tuberculosis (TB). Although controversy exists about its efficacy, the BCG vaccine is able to protect newborns and children against disseminated forms of TB, but fails to protect adults against active forms of TB. In the last few years, interest in the mucosal delivery route for the vaccine has been increasing owing to its increased capacity to induce protective immune responses both in the mucosal and the systemic immune compartments. Here, we show the importance of this route of vaccination in newly developed vaccines, especially for vaccines against TB.