Influenza surveillance among children with pneumonia admitted to a district hospital in coastal Kenya, 2007-2010

Background: Influenza data gaps in sub-Saharan Africa include incidence, case fatality, seasonal patterns, and associations with prevalent disorders. Methods: Nasopharyngeal samples from children aged <12 years who were admitted to Kilifi District Hospital during 2007–2010 with severe or very severe pneumonia and resided in the local demographic surveillance system were screened for influenza A, B, and C viruses by molecular methods. Outpatient children provided comparative data. Results: Of 2002 admissions, influenza A virus infection was diagnosed in 3.5% (71), influenza B virus infection, in 0.9% (19); and influenza C virus infection, in 0.8% (11 of 1404 tested). Four patients with influenza died. Among outpatients, 13 of 331 (3.9%) with acute respiratory infection and 1 of 196 without acute respiratory infection were influenza positive. The annual incidence of severe or very severe pneumonia, of influenza (any type), and of influenza A, was 1321, 60, and 43 cases per 100 000 <5 years of age, respectively. Peak occurrence was in quarters 3–4 each year, and approximately 50% of cases involved infants: temporal association with bacteremia was absent. Hypoxia was more frequent among pneumonia cases involving influenza (odds ratio, 1.78; 95% confidence interval, 1.04–1.96). Influenza A virus subtypes were seasonal H3N2 (57%), seasonal H1N1 (12%), and 2009 pandemic H1N1 (7%). Conclusions: The burden of influenza was small during 2007–2010 in this pediatric hospital in Kenya. Influenza A virus subtype H3N2 predominated, and 2009 pandemic influenza A virus subtype H1N1 had little impact

Influenza epidemiology, vaccine coverage and vaccine effectiveness in sentinel Australian hospitals in 2013: the Influenza Complications Alert Network

The National Influenza Program aims to reduce serious morbidity and mortality from influenza by providing public funding for vaccination to at-risk groups. The Influenza Complications Alert Network (FluCAN) is a sentinel hospital-based surveillance program that operates at 14 sites in all states and territories in Australia. This report summarises the epidemiology of hospitalisations with confirmed influenza, estimates vaccine coverage and influenza vaccine protection against hospitalisation with influenza during the 2013 influenza season. In this observational study, cases were defined as patients admitted to one of the sentinel hospitals, with influenza confirmed by nucleic acid testing. Controls were patients who had acute respiratory illnesses who were test-negative for influenza. Vaccine effectiveness was estimated as 1 minus the odds ratio of vaccination in case patients compared with control patients, after adjusting for known confounders. During the period 5 April to 31 October 2012, 631 patients were admitted with confirmed influenza at the 14 FluCAN sentinel hospitals. Of these, 31% were more than 65 years of age, 9.5% were Indigenous Australians, 4.3% were pregnant and 77% had chronic co-morbidities. Influenza B was detected in 30% of patients. Vaccination coverage was estimated at 81% in patients more than 65 years of age but only 49% in patients aged less than 65 years with chronic comorbidities. Vaccination effectiveness against hospitalisation with influenza was estimated at 50% (95% confidence interval: 33%, 63%, P<0.001). We detected a significant number of hospital admissions with confirmed influenza in a national observational study. Vaccine coverage was incomplete in at-risk groups, particularly non-elderly patients with medical comorbidities. Our results suggest that the seasonal influenza vaccine was moderately protective against hospitalisation with influenza in the 2013 season. This work i

TIV vaccination modulates host responses to influenza virus infection that correlate with protection against bacterial superinfection

Background: Influenza virus infection predisposes to secondary bacterial pneumonia. Currently licensed influenza vaccines aim at the induction of neutralizing antibodies and are less effective if the induction of neutralizing antibodies is low and/or the influenza virus changes its antigenic surface. We investigated the effect of suboptimal vaccination on the outcome of post-influenza bacterial superinfection. Methods: We established a mouse vaccination model that allows control of disease severity after influenza virus infection despite inefficient induction of virus-neutralizing antibody titers by vaccination. We investigated the effect of vaccination on virus-induced host immune responses and on the outcome of superinfection with Staphylococcus aureus. Results: Vaccination with trivalent inactivated virus vaccine (TIV) reduced morbidity after influenza A virus infection but did not prevent virus replication completely. Despite the poor induction of influenza-specific antibodies, TIV protected from mortality after bacterial superinfection. Vaccination limited loss of alveolar macrophages and reduced levels of infiltrating pulmonary monocytes after influenza virus infection. Interestingly, TIV vaccination resulted in enhanced levels of eosinophils after influenza virus infection and recruitment of neutrophils in both lungs and mediastinal lymph nodes after bacterial superinfection. Conclusion: These observations highlight the importance of disease modulation by influenza vaccination, even when suboptimal, and suggest that influenza vaccination is still beneficial to protect during bacterial superinfection in the absence of complete virus neutralization

Influenza Vaccine Effectiveness against Hospitalisation with Confirmed Influenza in the 2010-11 Seasons: A Test-negative Observational Study

Immunisation programs are designed to reduce serious morbidity and mortality from influenza, but most evidence supporting the effectiveness of this intervention has focused on disease in the community or in primary care settings. We aimed to examine the effectiveness of influenza vaccination against hospitalisation with confirmed influenza. We compared influenza vaccination status in patients hospitalised with PCR-confirmed influenza with patients hospitalised with influenza-negative respiratory infections in an Australian sentinel surveillance system. Vaccine effectiveness was estimated from the odds ratio of vaccination in cases and controls. We performed both simple multivariate regression and a stratified analysis based on propensity score of vaccination. Vaccination status was ascertained in 333 of 598 patients with confirmed influenza and 785 of 1384 test-negative patients. Overall estimated crude vaccine effectiveness was 57% (41%, 68%). After adjusting for age, chronic comorbidities and pregnancy status, the estimated vaccine effectiveness was 37% (95% CI: 12%, 55%). In an analysis accounting for a propensity score for vaccination, the estimated vaccine effectiveness was 48.3% (95% CI: 30.0, 61.8%). Influenza vaccination was moderately protective against hospitalisation with influenza in the 2010 and 2011 seasons

Analysis of the Morbidity and Mortality of Severe Influenza Infection in Clark County, Nevada for the 2010-2011 Influenza Season

Throughout the duration of any influenza season, influenza strains have the ability to evolve through mutation causing alterations in virulence. These changes may result in severe illness or death among susceptible populations; therefore, it is important to closely monitor influenza-associated hospitalizations and deaths. The University of Nevada, Las Vegas in collaboration with the Southern Nevada Health District analyzed data from the hospitalized influenza morbidity and mortality surveillance project for Clark County for the 2010-2011 influenza season. Among the study population (N= 158): the influenza strain type was found to be significantly associated with deaths (n= 25), vaccination status was not found to be significantly associated with death among hospitalized patients, and transformed data showed no statistically significant difference in the mean length of hospital stay based on the influenza strain type. These results will help inform public health agencies of the impact of influenza-associated hospitalizations and deaths, and inform the design of future surveillance systems

Effectiveness of an influenza vaccine programme for care home staff to prevent death, morbidity, and health service use among residents: cluster randomised controlled trial

Objective To determine whether vaccination of care home staff against influenza indirectly protects residents.Design Pair matched cluster randomised controlled trial.Setting Large private chain of UK care homes during the winters of 2003-4 and 2004-5.Participants Nursing home staff (n = 1703) and residents (n = 2604) in 44 care homes (22 intervention homes and 22 matched control homes).Interventions Vaccination offered to staff in intervention homes but not in control homes.Main outcome measures The primary outcome was all cause mortality of residents. Secondary outcomes were influenza-like illness and health service use in residents.Results In 2003-4 vaccine coverage in full time staff was 48.2% (407/884) in intervention homes and 5.9% (51/859) in control homes. In 2004-5 uptake rates were 43.2% (365/844) and 3.5% (28/800). National influenza rates were substaritially below average in 2004-5. In the 2003-4 period of influenza activity significant decreases were found in mortality of residents in intervention homes compared with control homes (rate difference - 5.0 per 100 residents, 95% confidence interval - 7.0 to - 2.0) and in influenza-like illness (P = 0.004), consultations with general practitioners for influenza-like illness (P = 0.008), and admissions to hospital with influenza-like illness (P = 0.009). No significant differences were found in 2004-5 or during periods of no influenza activity in 2003-4.Conclusions Vaccinating care home staff against influenza can prevent deaths, health service use, and influenza-like illness in residents during periods of moderate influenza activity

Iowa Influenza Surveillance Network Final Report 2006-2008

The Iowa Influenza Surveillance Network (IISN) tracks the overall activity, age groups impacted, outbreaks, type and strain, and severity of seasonal influenza. In the 2006-2007 season the network had more than 90 reporting sites that included physicians, clinics, hospitals, schools and long term care facilities (Appendix A). Other non-network reporters who contributed influenza data included medical clinics, hospitals, laboratories, local public health departments and neighboring state health departments. 010203040506070424548495051521234567891011121314MMWR weekNumber of cases2006-20072005-2006 The 2006-2007 influenza season in Iowa began earlier than any previously recorded data indicates, however, the season’s peak occurred much later in the season. In addition to early cases, this season was also unusual in that all three anticipated strains (AH1N1, AH3N2, and B) were reported by the first of December (Appendix B). The first laboratory-confirmed case in the 2005-2006 season was identified December 5, 2005; the first case for the 2006-2007 season was on November 2, 2006. The predominant strain for 2005-2006 was influenza AH3, but for 2006-2007 both influenza AH1 and B dominated influenza infections. However improvements in influenza specimen submission to the University Hygienic Laboratory may have also played a role in early detection and overall case detection. In summary, all influenza activity indicators show a peak between the MMWR weeks 5 and 9 (i.e. February 14- March 4). Children from five years to eight years of age were impacted more than other age groups. There were few influenza hospitalizations and fatalities in all age groups

Influenza Vaccination of young children or Antibody Immune Response and Protection after Inactivated Influenza Vaccine in Children – A Literature Review

Influenza virus infection is a major cause of morbidity and mortality in at risk populations. Children, especially under the age of two, are at an increased risk of complications associated with influenza virus infection. Evidence suggests that a single dose of influenza vaccine does not adequately protect children against circulating influenza virus. The Centers for Disease Control and Prevention’s (CDC) Advisory Committee on Immunizations Practices (ACIP) recommends two doses of influenza vaccine, spaced at least four weeks apart, before the beginning of the influenza season for children between the ages of 6 months through 8 years receiving influenza vaccine for the first time. The initial dose is thought to prime the immune system, and the second dose is thought to mount a protective antibody response. We conducted a systematic literature review to summarize current evidence from randomized controlled trials (RCTs) and observational studies that compared immunogenicity and vaccine effectiveness (VE) after one or two doses of influenza vaccine in children to evaluate the evidence basis for the CDC recommendations. The search identified 727 unique articles and 82 were screened in full text for eligibility. A total of 26 studies met inclusion criteria, 16 immunogenicity and 10 VE studies. Overall, the evidence demonstrates increased immunogenicity and VE after two doses of influenz