Fifteen years of epidemiologic, virologic and syndromic influenza surveillance: A focus on type B virus and the effects of vaccine mismatch in Liguria region, Italy

In order to estimate the burden of influenza and to describe the genetic evolutionary pattern and antigenic variability of type B viral strains, data deriving from 3 surveillance systems active in Liguria region, Northern Italy, were described. Since the re-emergence of the Victoria lineage in 2001, the clinical-epidemiological and syndromic surveillances demonstrated the heavy burden of influenza like illness (ILI) syndrome. Focusing on type B influenza virus, it predominated or played a relevant epidemic role in the 50% of the evaluated influenza seasons. Furthermore, the virologic surveillance demonstrated the frequent co-circulation of both lineages an heterogeneous circulation of different influenza B strains, determining a partial or complete mismatch in at least 6 influenza seasons. The undemonstrated cross-reactivity between lineages and the unpredictability of predominant lineage arose the scientific debate about the opportunity to include the quadrivalent influenza vaccine among the preventive tools to improve the protection against type B viruses. The integration of different surveillance systems highly contribute to estimate the poorly evaluated burden of type B influenza virus and help to find variants to include in the vaccine formulation.

Genetic polymorphisms of IL28b gene as predictors of response to dual therapy in genotypes 1 and 4-HCV and HIV/HCV-infected patients

We describe the genotypes and allele distribution of interleukin 28B (IL28B) rs12979860 and rs8099917 single nucleotide polymorphisms (SNPs) in hepatitis C virus (HCV) G1-4 infected patients, to assess predictive ability and to determine whether the combined determination of two IL28B SNPs might improve sustained virologic response (SVR) prediction of both in HCV mono- and HIV/HCV co-infected patients. IL28B SNPs were genotyped in 269 patients, 181 mono- and 88 co-infected, treated with pegylated interferon and ribavirin. Data stratified by HCV mono- and HCV/HIV co-infected patients showed that 58% and 31% of the rs12979860CC carriers and 49% and 21% of the rs8099917TT carriers had SVR. IL28B SNPs, HCV mono-infection and HCV RNA load were associated with SVR as independent predictors in the two study groups as a whole. ROC curve analyses in the two populations separately, based on gender, age, baseline HCV RNA load and rs12979860/rs8099917 revealed similar receiver operating characteristics (ROC) areas under the curve values. Combining the determination of IL28B SNPs, rs8099917 genotyping improved the response prediction in rs12979860CT carriers only in mono-infected patients. In the era of direct-acting antiviral agents, adopting SVR baseline predictors to orientate naïve-patient management represents an important issue. A model involving IL28B SNPs appears able to predict SVR in both populations.

Seroprevalence and vaccination coverage of vaccine-preventable diseases in perinatally HIV-1-infected patients

BACKGROUND

Even in the era of highly active antiretroviral therapy (HAART), HIV-infected subjects are at higher risk of complications from vaccine-preventable diseases than those uninfected. The current international guidelines strongly recommend that these patients should receive all the routine childhood vaccinations. Although these children represent an appropriate target for immunization, the available data indicate suboptimal coverage rates.

METHODS

To evaluate seroprotection/seropositivity rates and vaccination coverage against the common vaccine-preventable diseases, all patients with vertically transmitted HIV-1 infection who attended San Martino Hospital were enrolled. Blood samples were collected for testing antibodies against diphtheria, tetanus, hepatitis A and B viruses by Enzyme-Linked ImmunoSorbent Assay and polioviruses by microneutralization test. In order to assess immunization coverage, retrospectively was recorded the vaccination history collecting data from Regional Immunization Database.

RESULTS

A total of 39 perinatally HIV-1 infected patients were included in the study. At the time of serum was obtained, the mean age was 18,1 years (range: 6-28). The median CD4+ T-lymphocyte count was 702 cells/mm(3) (2-1476 cells/mm(3)). Twenty-nine (74.4%) patients were found with HIV RNA load < 50 copies/mL. The proportion of subjects with protective anti-tetanus and anti-HBs were 43.6% and 30.8%, respectively. Seroprotection rates about 20% against rubella and measles were found, less than 20% against all the other antigens investigated. In particular, all patients resulted susceptible to mumps. High immunization rates were observed for polio and HBV (100% and 92.3%, respectively) and suboptimal for diphtheria-tetanus (84.6%). For the other recommended vaccines the rates were generally low. None of the patients received varicella vaccine doses.

CONCLUSIONS

As in the HAART era the vertically acquired HIV infection has become a chronic treatable disease, the vaccine-induced long-term protection plays an increasingly significant role; despite good initial response to primary vaccination, subsequent decline and loss of detectable antibodies may be prevented by additional strategies for booster doses of vaccines in adolescents and young adults.

Head-to-head comparison of an intradermal and a virosome influenza vaccine in patients over the age of 60: evaluation of immunogenicity, cross-protection, safety and tolerability

In the present study we first compare immunogenicity against vaccine and heterologous circulating A(H1N1)pdm09 strains, tolerability and safety of intradermal Intanza 15 μg and of virosomal adjuvanted, intramuscularly delivered influenza vaccine, Inflexal V, in healthy elderly volunteers. Five-hundred participants were enrolled in the study and randomly assigned to the two vaccine groups to receive either one dose of Intanza 15 μg or Inflexal V vaccine. All subjects reported solicited local and systemic reactions occurred within 7 d after vaccination and unsolicited adverse events up to 21 d post-immunization and any serious adverse event appeared during the study. A subset of 55 participants was randomly selected for immunogenicity and cross-protection evaluations. Serum samples were collected before and 1 and 3 mo after immunization. Antibody responses were measured using hemagglutination inhibition (HI) against all viruses used in the study and neutralization (NT) assays against A(H1N1)pdm09 strains. At least one of the CHMP criteria for influenza vaccine approval in the elderly was met by virosomal vaccine against all the tested viruses; intradermal vaccine met all criteria against all strains. Several parameters of immune response against strains with a different antigenic pattern from that of vaccine A/California/04/09(H1N1)pdm09 were significantly higher in the intradermal vaccine group compared with the virosomal group. Safety and systemic tolerability of both vaccines were excellent, but injection site reactions occurred significantly more frequently in the intradermal vaccination group. Immunogenicity of Intanza 15 μg intradermal vaccine tended to be higher than that of Inflexal V against heterologous strains in healthy elderly.

Carriage of Streptoccoccus pneumoniae in healthy adults aged 60 years or over in a population with very high and long-lasting pneumococcal conjugate vaccine coverage in children: rationale and perspectives for PCV13 implementation

A serial cross-sectional study of nasopharyngeal carriage among adults aged 60 y or over was conducted in winter-spring 2012 with the aim to describe circulating Streptococcus pneumoniae in an area, Liguria Administrative Region, where the vaccine was implemented for a decade and coverage in pediatric age group reached a value close to 100% for more than 5 y, determining a picture of very high vaccine immunological pressure. The serotype-specific carriage picture in adults was compared with that observed in children by means of a cross-sectional study performed one year before using the same sampling and laboratory methods.   Cluster sampling enrolled 283 adults, representative of the open population. Detection of multi-serotype carriage was performed using, real-time PCR and primer specific PCRs. Carriage prevalence of participants with at least one positive sample adjusted for age, i.e., period prevalence, was 18.7%, considering the Ligurian population as standard population, showing that the pneumococcal carriage in the elderly is not a rare event as emerged in other surveys. The long-term use of PCV7 has resulted in strong decrease of vaccine types carriage among adults and children. A multivariate analysis showed that age class and contact with children attending day care covariates were strongly associated with Streptococcus pneumoniae carriage. A strong link between the picture observed in < 5-y-old children and ≥ 60-y-old adults emerged: a strong correlation of specific-serotype prevalence between adults and children and risk factor analysis supported the role played by inter-age-group transmission.

Bacterial carriage and respiratory tract infections in subjects > or = 60 years during an influenza season: implications for the epidemiology of community acquired pneumonia and influenza vaccine effectiveness

INTRODUCTION

During the 2010/11 influenza season an epidemiological prospective cohort active study was organized, to evaluate etiologic role due to the main bacteria and viruses causing Community Acquired Pneumonia (CAP) and Influenza like-illness (ILl) in elderly and to explore the role of the bacterial nose-pharingeal carriage in subjects with respiratory tract infections.

METHODS

An integrated active surveillance of a cohort of adults aged > or = 60 y based on a double prospective and retrospective mechanisms of capture of ILl and CAP cases was organized. Samples were collected from all ILI and CAP prospectively identified. The samples were be tested by multiplex PCR for detection of the main respiratory bacteria and viruses.

RESULTS AND DISCUSSION

The study population amounted to 2,551 adults. During the 2010/11 influenza season, the ILl cumulative incidence was 4.2%, that was twice higher than that calculated by regional sentinel-based Influenza surveillance system during the 2010/11 season in the elderly (2.2%). Among 45 patients with ILI of which had been collected the swab, 17 (37.8%) were positive for influenza viruses and 2 (4.4%) for RSV, 6 (13.3%) patients carried Streptococcus pn and 6 (13.3%) Haemophilus in. In the same period, 7 CAP cases were observed; 3 cases were prospectively identified and samples were collected, while 4 cases were retrospectively detected. The CAP cumulative incidence was 0,3%. The influenza vaccine effectiveness in prevention of laboratory-confirmed influenza emerged by our study was 61%, in condition of good antigenic matching between vaccine and circulating strains observed during the 2010/11. These data contribute to better defining the epidemiological picture of upper and lower respiratory tract infections, fundamental information in light of the recent introduction of new vaccines for prevention of pneumonia in the elderly, including 13-valent conjugate pneumococcal vaccine.