pH1N1 Influenza Research Articles

Impact of swine influenza and quarantine measures on patients and households during the H1N1/09 pandemic

To assess the secondary attack rates (SAR) and impact of the 2009 H1N1 epidemic in Melbourne, Victoria, Australia, and the measures implemented to control household transmission. Patients with polymerase chain reaction-confirmed influenza A and pandemic H1N1 (pH1N1) were identified from hospital and microbiology laboratory records and asked to take part in a retrospective survey. Information obtained included: the constellation of symptoms, contact history, secondary infection, and household information, including adherence and attitudes towards quarantine measures. The overall SAR of pH1N1 index patients was 30.6%, but a significantly lower SAR was noted with oseltamivir treatment (36.6% vs 22.8%, p < 0.05). The greatest reduction in SAR was observed when index patients aged 0-4 y received oseltamivir (83.3% vs 22.2%, p < 0.01). Quarantine was requested of 65.8% of patients and 92.8% self-reported adhering to recommendations. pH1N1 index patients, the number of median days bed-bound is 2.5 days, being unable or too sick to work for a median of 5.0 days, and lost a median of 7.0 days of work for reasons related to an influenza-like illness. The pH1N1 influenza pandemic had a significant clinical impact on households. Public health interventions such as oseltamivir treatment of index cases were beneficial in reducing secondary attack rates, whilst quarantine measures were found to have high rates of self-reported compliance, understanding, and acceptability.

A two-year surveillance of 2009 pandemic influenza A (H1N1) in Guangzhou, China: from pandemic to seasonal influenza?

In this two-years surveillance of 2009 pandemic influenza A (H1N1) (pH1N1) in Guangzhou, China, we reported here that the scale and duration of pH1N1 outbreaks, severe disease and fatality rates of pH1N1 patients were significantly lower or shorter in the second epidemic year (May 2010-April 2011) than those in the first epidemic year (May 2009-April 2010) (P<0.05), but similar to those of seasonal influenza (P>0.05). Similar to seasonal influenza, pre-existing chronic pulmonary diseases was a risk factor associated with fatal cases of pH1N1 influenza. Different from seasonal influenza, which occurred in spring/summer seasons annually, pH1N1 influenza mainly occurred in autumn/winter seasons in the first epidemic year, but prolonged to winter/spring season in the second epidemic year. The information suggests a tendency that the epidemics of pH1N1 influenza may probably further shift to spring/summer seasons and become a predominant subtype of seasonal influenza in coming years in Guangzhou, China.

Successful use of extracorporeal membrane oxygenation for pH1N1-induced refractory hypoxemia in a child with hypoplastic left heart syndrome

To report the first successful use of extracorporeal membrane oxygenation for acute respiratory distress syndrome secondary to 2009 pH1N1 influenza A infection in a child status post the Fontan operation for hypoplastic left heart syndrome. Individual case report. Pediatric intensive care unit. We describe a 7-yr-old boy with a history of the Fontan operation for hypoplastic left heart syndrome admitted with acute respiratory distress syndrome secondary to 2009 pH1N1 influenza A infection. Cannulation for venoarterial extracorporeal membrane oxygenation. In this patient with a history of complex congenital heart disease and repair, extracorporeal membrane oxygenation was a successful rescue therapy for refractory pH1N1-induced respiratory failure. Extracorporeal membrane oxygenation can be successfully applied for refractory respiratory failure, even in the setting of significant underlying comorbidity. With emerging data to support the role of extracorporeal membrane oxygenation in improving mortality for refractory hypoxemia secondary to pH1N1, it is prudent to strongly consider the use of extracorporeal support in patients with underlying diseases or comorbidities that may have previously precluded them from being candidates for this therapy.

Invasive Bacterial Infections in Relation to Influenza Outbreaks, 2006–2010

We aimed to define the excess morbidity associated with bloodstream infections (BSIs), imposed by pandemic H1N1 influenza during 2009-2010 (pH1N1/2009-2010) and seasonal influenza. Eight hospitals, accounting for 33% of hospitalizations in Israel, provided data on BSI during 2006-2010. The age-specific incidence of BSI due to Streptococcus pneumoniae, Staphylococcus aureus, and Streptococcus pyogenes was determined. BSI incidence rate ratios (IRRs) during seasonal and pH1N1 influenza seasons were assessed. Regular influenza seasons were characterized by increased rates of S. pneumoniae BSI but with no increase in S. aureus and S. pyogenes BSI rates. The pH1N1/2009-2010 influenza outbreak was characterized by (1) higher rates of S. pneumoniae bacteremia among children but not among adults (IRRs for S. pneumoniae BSI among children aged 0-4 years during the summer and winter of 2009-2010 were 14.8 [95% confidence interval {CI}, 5-43.7] and 6.5 [95% CI, 3.6-11.8], compared with 2006-2009 summers and influenza-active winter weeks, respectively [P < .0001]), higher rates of S. aureus BSI in all age groups (IRRs during the summer and winter of 2009-2010 were 1.6 [95% CI, 1.4-1.9] and 1.5 [95% CI, 1.2-1.7], compared with 2006-2009 summers and influenza-active weeks, respectively [P < .0001]), higher rates of S. pyogenes BSI during 2009-2010 influenza season (IRR 2.7 [95% CI, 1.6-4.6] and 3.3 [95% CI, 1.9-5.8] during the summer and winter of 2009-2010, compared with 2006-2009 summers and influenza-active weeks, respectively [P < .0001]). pH1N1 influenza seasons were characterized by marked increases in invasive S. aureus and S. pyogenes infections among children and adults, with the highest increase in S. pneumoniae BSI among children.

Emergence of a New Swine H3N2 and Pandemic (H1N1) 2009 Influenza A Virus Reassortant in Two Canadian Animal Populations, Mink and Swine

A swine H3N2 (swH3N2) and pandemic (H1N1) 2009 (pH1N1) influenza A virus reassortant (swH3N2/pH1N1) was detected in Canadian swine at the end of 2010. Simultaneously, a similar virus was also detected in Canadian mink based on partial viral genome sequencing. The origin of the new swH3N2/pH1N1 viral genes was related to the North American swH3N2 triple-reassortant cluster IV (for hemagglutinin [HA] and neuraminidase [NA] genes) and to pH1N1 for all the other genes (M, NP, NS, PB1, PB2, and PA). Data indicate that the swH3N2/pH1N1 virus can be found in several pigs that are housed at different locations.

Cytokine Response Patterns in Severe Pandemic 2009 H1N1 and Seasonal Influenza among Hospitalized Adults

BackgroundStudying cytokine/chemokine responses in severe influenza infections caused by different virus subtypes may improve understanding on pathogenesis.MethodsAdults hospitalized for laboratory-confirmed seasonal and pandemic 2009 A/H1N1 (pH1N1) influenza were studied. Plasma concentrations of 13 cytokines/chemokines were measured at presentation and then serially, using cytometric-bead-array with flow-cytometry and ELISA. PBMCs from influenza patients were studied for cytokine/chemokine expression using ex-vivo culture (Whole Blood Assay,±PHA/LPS stimulation). Clinical variables were prospectively recorded and analyzed.Results63 pH1N1 and 53 seasonal influenza patients were studied. pH1N1 patients were younger (mean±S.D. 42.8±19.2 vs 70.5±16.7 years), and fewer had comorbidities. Respiratory/cardiovascular complications were common in both groups (71.4% vs 81.1%), although severe pneumonia with hypoxemia (54.0% vs 28.3%) and ICU admissions (25.4% vs 1.9%) were more frequent with pH1N1. Hyperactivation of the proinflammatory cytokines IL-6, CXCL8/IL-8, CCL2/MCP-1 and sTNFR-1 was found in pH1N1 pneumonia (2–15 times normal) and in complicated seasonal influenza, but not in milder pH1N1 infections. The adaptive-immunity (Th1/Th17)-related CXCL10/IP-10, CXCL9/MIG and IL-17A however, were markedly suppressed in severe pH1N1 pneumonia (2–27 times lower than seasonal influenza; P−values<0.01). This pattern was further confirmed with serial measurements. Hypercytokinemia tended to be sustained in pH1N1 pneumonia, associated with a slower viral clearance [PCR-negativity: day 3–4, 55% vs 85%; day 6–7, 67% vs 100%]. Elevated proinflammatory cytokines, particularly IL-6, predicted ICU admission (adjusted OR 12.6, 95%CI 2.6–61.5, per log10unit increase; P = 0.002), and correlated with fever, tachypnoea, deoxygenation, and length-of-stay (Spearman's rho, P-values<0.01) in influenza infections. PBMCs in seasonal influenza patients were activated and expressed cytokines ex vivo (e.g. IL-6, CXCL8/IL-8, CCL2/MCP-1, CXCL10/IP-10, CXCL9/MIG); their ‘responsiveness’ to stimuli was shown to change dynamically during the illness course.ConclusionsA hyperactivated proinflammatory, but suppressed adaptive-immunity (Th1/Th17)-related cytokine response pattern was found in severe pH1N1 pneumonia, different from seasonal influenza. Cytokine/immune-dysregulation may be important in its pathogenesis.

Assessing the impact of confounding (measured and unmeasured) in a case–control study to examine the increased risk of pandemic A/H1N1 associated with receipt of the 2008–9 seasonal influenza vaccine

This study examines the role of measured and unmeasured confounding in the relationship between the 2008-9 seasonal influenza vaccine and pandemic H1N1 (pH1N1) influenza virus. Data were taken from a test-negative case-control study of 462 lab confirmed pandemic A/H1N1 (pH1N1) cases and 484 test-negative controls. Adjusted odds ratios (OR) and 95% confidence intervals (CI) were derived using multivariate logistic regression. The analysis was repeated using propensity matching. A sensitivity analysis was conducted to quantify the impact of a hypothetical unmeasured confounder. Cases were more likely to have received the seasonal influenza vaccine after adjusting for multiple confounders using multivariate regression (OR 1.82, 95% CI: 1.25-2.65), using propensity matching (OR 1.86, 95% CI: 1.19-2.92) and in subsequent sensitivity analyses. An unmeasured confounder would need a prevalence of 20%, an odds ratio with the vaccine and pH1N1 of ≥3.5 and ≥3.0 (respectively) to result in a non-significant association. Using a prevalence of 40% the respective associations were 3.0 and 2.5. A significant positive association between the seasonal influenza vaccine and lab confirmed pH1N1 was observed after considering multiple confounders and using different methods for confounder adjustment. This was not likely explained by an unmeasured confounder given the prevalence and strength of association needed to result in a non-significant association.

Use of influenza vaccines in children with an egg allergy

Children are at increased risk of morbidity from influenza. Influenza vaccines are grown in eggs, leading to a minute amount of egg protein in their composition. Recent research and new practice parameters spurred by the 2009 global influenza pandemic have challenged the need to withhold influenza vaccine from patients with an egg allergy. The available data suggest that anaphylaxis from influenza vaccines is exceptionally rare, even in patients with an egg allergy. Reported allergic reactions to trivalent inactivated influenza vaccine and pH1N1 influenza vaccines have been rare; when reactions occurred, they have not caused anaphylaxis. This position statement reviews the available evidence on influenza vaccine/egg allergy-related anaphylaxis, and recommends protocols to safely administer the trivalent inactivated influenza vaccine in lower- and higher-risk children with an egg allergy.

Cross-protective immunity against influenza pH1N1 2009 viruses induced by seasonal influenza A (H3N2) virus is mediated by virus-specific T-cells

Influenza A (H1N1) viruses of swine origin were introduced into the human population in 2009 and caused a pandemic. The disease burden in the elderly was relatively low, which was attributed to the presence of cross-reacting serum antibodies in this age group, which were raised against seasonal influenza A (H1N1) viruses that circulated before 1957. It has also been described how infection with heterosubtypic influenza viruses can induce some degree of protection against infection by a novel strain of influenza virus. Here, we assess the extent of protective immunity against infection with the 2009 influenza A (H1N1) pandemic influenza virus that is afforded by infection with a seasonal influenza A (H3N2) virus in mice. Mice that experienced a primary A (H3N2) influenza virus infection displayed reduced weight loss after challenge infection and cleared the 2009 influenza A (H1N1) virus infection more rapidly. To elucidate the correlates of protection of this heterosubtypic immunity to pandemic H1N1 virus infection, adoptive transfer experiments were carried out by using selected post-infection lymphocyte populations. Virus-specific CD8(+) T-cells in concert with CD4(+) T-cells were responsible for the observed protection. These findings may not only provide an explanation for epidemiological differences in the incidence of severe pandemic H1N1 infections, they also indicate that the induction of cross-reactive virus-specific CD8(+) and CD4(+) T-cell responses may be a suitable approach for the development of universal influenza vaccines.

Factors associated with hypoxemia in children infected with pandemic H1N1 2009 influenza virus

Hypoxemia was found to be a major cause of death from pandemic H1N1 2009 influenza (pH1N1) infection. There are limited data on factors associated with hypoxemia in children infected with pH1N1 influenza virus. Factors associated with hypoxemia were investigated using univariate and multivariate analysis in 76 hospitalized pediatric patients with laboratory-confirmed H1N1 influenza virus infection at Gyeongsang National University Hospital in Jinju, South Korea, from August 2009 to January 2010 by retrospective chart review. Hypoxemia occurred in 17 children (22%), of whom three were admitted to an intensive care unit and one died. Hypoxemic patients were significantly more likely to have a higher respiratory rate, pulse rate, white blood cell count (WBC), and C-reactive protein level, as well as a longer hospital stay. Respiratory rate and WBC count at admission were independently associated with hypoxemia as determined on multivariate analysis, and this association was found to be clinically significant. Although a higher WBC count and respiratory rate may not be specific for pHINI but represent the degree of disease severity for any infectious respiratory disease in general, clinicians can use these parameters at admission as useful, early indicators of disease severity in pediatric pH1N1 infection.

Low Influenza Vaccination Rates Among Child Care Workers in the United States: Assessing Knowledge, Attitudes, and Behaviors

Influenza can spread quickly among children and caregivers in child day care settings. Vaccination is the most effective method to prevent influenza. We determined 2009 pandemic influenza A (H1N1) (pH1N1) and seasonal influenza vaccination rates during the 2009-2010 influenza season among child care center employees, assessed knowledge and attitudes regarding the vaccines, and determined factors associated with vaccine receipt. Using a cross-sectional study design, from January 30-March 1, 2010, we surveyed 384 (95%) of 403 employees at 32 licensed child centers in the United States about personal and work characteristics, vaccine receipt, and knowledge and attitudes regarding each vaccine. Forty-five (11%) and eighty five (22%) respondents reported receiving the pH1N1 and seasonal influenza vaccines, respectively. The most common reasons cited for not getting either vaccine were "I don't think I need the vaccine," "I don't think the vaccine will keep me from getting the flu," and "the vaccine is not safe." Factors independently associated with receipt of either vaccine included belief in its efficacy, having positive attitudes towards it, and feeling external pressure to get it. Child care center employees had low rates of pH1N1 and seasonal influenza vaccination largely due to misconceptions about the need for and efficacy of the vaccine. Public health messages should address misconceptions about vaccines, and employers should consider methods to maximize influenza vaccination of employees as part of a comprehensive influenza prevention program.

Increased Pathogenicity of a Reassortant 2009 Pandemic H1N1 Influenza Virus Containing an H5N1 Hemagglutinin

A novel H1N1 influenza virus emerged in 2009 (pH1N1) to become the first influenza pandemic of the 21st century. This virus is now cocirculating with highly pathogenic H5N1 avian influenza viruses in many parts of the world, raising concerns that a reassortment event may lead to highly pathogenic influenza strains with the capacity to infect humans more readily and cause severe disease. To investigate the virulence of pH1N1-H5N1 reassortant viruses, we created pH1N1 (A/California/04/2009) viruses expressing individual genes from an avian H5N1 influenza strain (A/Hong Kong/483/1997). Using several in vitro models of virus replication, we observed increased replication for a reassortant CA/09 virus expressing the hemagglutinin (HA) gene of HK/483 (CA/09-483HA) relative to that of either parental CA/09 virus or reassortant CA/09 expressing other HK/483 genes. This increased replication correlated with enhanced pathogenicity in infected mice similar to that of the parental HK/483 strain. The serial passage of the CA/09 parental virus and the CA/09-483HA virus through primary human lung epithelial cells resulted in increased pathogenicity, suggesting that these viruses easily adapt to humans and become more virulent. In contrast, serial passage attenuated the parental HK/483 virus in vitro and resulted in slightly reduced morbidity in vivo, suggesting that sustained replication in humans attenuates H5N1 avian influenza viruses. Taken together, these data suggest that reassortment between cocirculating human pH1N1 and avian H5N1 influenza strains will result in a virus with the potential for increased pathogenicity in mammals.

Immunogenicity and safety of monovalent influenza A (H1N1) 2009 in HIV-infected Thai children

To evaluate the immunogenicity and safety of the monovalent pandemic influenza A (H1N1) 2009 (pH1N1) vaccine in HIV-infected Thai children, 2 doses, 28days apart, of non-adjuvant monovalent pH1N1 vaccine (Panenza(®) by Sanofi Pasteur, 15μg/dose) provided by the National Health Promotion Program of the Thai Ministry of Public Health were given to HIV-infected children. Immunogenicity was measured by hemagglutination inhibition test (HAI) using two antigens, pH1N1 (A/Thailand/104/09) and seasonal influenza A H1N1 (A/Brisbane/59/07-like), at baseline, and 28days after each dose. Serologic response was defined as four-fold rising of HAI titer or HAI titer ≥1:40 for those with baseline titer ≤1:10. Adverse events were recorded for 7days after each vaccination. Of the 119 HIV-infected children enrolled, 60 (50.4%) were female with a median (IQR) age of 10.4 (7.2-13.7)years. All but 2 (98.3%) children were receiving antiretroviral therapy. At baseline, the median CD4 cell count was 782 (570-1149)cells/mm(3), 91 (80.5%) children had HIV RNA level <40copies/ml. The baseline HAI titer ≥1:40 for pH1N1 and seasonal H1N1 were 45.4%, and 39.5%, respectively. At 28 days after doses 1 and 2, the serologic response rates for pH1N1 were 54.2% and 67.8% with the geometric mean titer of 109.9 and 141.8; and serologic response rate when tested with seasonal H1N1 were 2.5% and 3.5%, respectively. The presence of baseline HAI titer for pH1N1 or seasonal H1N1 was found to be associated with serologic response. The vaccine was well tolerated. The results suggested that monovalent pH1N1 vaccine was immunogenic and safe in well controlled HIV-infected children with low level of cross reacting antibody to seasonal H1N1.

Behavioral change with influenza vaccination: Factors influencing increased uptake of the pandemic H1N1 versus seasonal influenza vaccine in health care personnel

Many health care personnel (HCP) choose not to get vaccinated against influenza despite recommendations to do so. The pH1N1 epidemic gave a unique opportunity to evaluate the attitudes to influenza vaccination of a group of HCP who routinely choose not to get vaccinated, but accepted the pH1N1 vaccine. HCP employed at a tertiary care hospital in Winnipeg, Canada who received the pH1N1 vaccine were invited to participate in an online survey asking about attitudes and experiences regarding seasonal and pH1N1 influenza and vaccination. Those eligible included primarily nurses, other clinical staff, and support staff, as few physicians work as employees. Of the 684 respondents (29% return rate), 504 reported routinely getting vaccinated (RV) for seasonal influenza and 180 reported routinely not getting vaccinated (NRV). These two groups had different attitude towards the two strains of influenza, with markedly lower level of concern about seasonal influenza than pH1N1 for the NRV group. The contrast was especially notable regarding the NRV's view of the seriousness of the illness, their sense of exposure risk, and their confidence in the vaccine effectiveness (for all, seasonal<pH1N1, p<0.001). The most common motivators for getting vaccinated for both NRV and RV groups related to concerns about personal or family safety, while the choice to decline seasonal vaccination related primarily to lack concern about the illness and concerns about vaccine effectiveness and safety. Coworkers were influential in the decision to get the pH1N1 vaccine for the NRV group. For HCP who do not routinely get the seasonal vaccination, perception of risk outweighing side effect concerns appeared to be a major influence in going ahead with the pH1N1 vaccine. Educational campaigns that focus on personal benefit, engage peer champions, and address concerns about the vaccine may improve influenza vaccine uptake among health care personnel.

Comparison of Pandemic and Seasonal Influenza in the Pediatric Emergency Department

Emergency department (ED) presentation of pediatric pandemic H1N1 (pH1N1) infection is not well characterized. Our objective was to describe the clinical manifestations of pH1N1 in the pediatric ED. We also compared these characteristics to seasonal influenza A, and explored risk factors for pH1N1 hospitalization. We conducted a retrospective cohort study at a pediatric hospital in Quebec City, Canada. Subjects were ED patients aged 0 to 17 years with laboratory-confirmed pH1N1 (April-July 2009) or seasonal influenza A (June 2006-March 2009). Clinical and laboratory data were analyzed by univariate and multivariate log-binomial regression. A total of 127 pH1N1 cases and 110 seasonal influenza cases were identified. pH1N1 patients were older (9.5 vs. 5.6 years; P < 0.0001) and presented more rapidly (2.8 vs. 3.5 days; P = 0.02). Clinical manifestations were similar, although gastrointestinal findings were less frequent in pH1N1 (relative risk [RR]: 0.49; 95% confidence interval [CI]: 0.37-0.65). Hospitalization risk was similar (RR: 1.12; 95% CI: 0.81-1.55), but hospitalized pH1N1 subjects were more frequently diagnosed with pneumonia (RR: 2.41; 95% CI: 1.16-5.00). In a multivariable model, age <2 years was independently associated with pH1N1 hospitalization (RR: 3.17; 95% CI: 1.78-5.65), whereas the absence of significant comorbidities decreased its risk (RR: 0.51; 95% CI: 0.31-0.85). After adjustment for age and delay to presentation, clinical manifestations and 21-day outcomes of pediatric pH1N1 were similar to those of seasonal influenza. pH1N1 patients with previously established risk factors for severe seasonal influenza experienced increased hospitalization risk. Our results suggest that pH1N1 clinical diagnosis and management in the pediatric ED can be performed in a manner similar to seasonal influenza.

Immunogenicity of a half-dose of adjuvanted 2009 pandemic H1N1 influenza vaccine in adults: a prospective cohort study

We aimed to assess the immunogenicity of a single half-dose of AS03-adjuvanted monovalent 2009 pandemic H1N1 vaccine in healthy adults. Healthy subjects age 20-60years were prospectively enrolled in a cohort receiving intramuscular administration of a single half-dose (1.875μg of hemagglutinin [HA]) of adjuvanted 2009 pandemic H1N1 influenza vaccine. Data from participants enrolled in a concomitant study of immunogenicity following a full-dose (3.75μg of HA) are presented concurrently. Sera for assessment of hemagglutination-inhibiting (HAI) antibody to the vaccine strain were obtained before and 14 or 21days after vaccination. Ninety-seven participants received a half-dose and 50 received a full-dose of vaccine. In the half-dose cohort, Food and Drug Administration criteria for immunogenicity regarding seroprotection and seroconversion rates were met for subjects aged 20-45years, but not for those aged 46-60years. There was no statistically significant difference in the proportion of individuals achieving a post-vaccination HAI titre of ≥1:40, the geometric mean titres of post-vaccination antibody, or the proportion of individuals with a four-fold or greater increase in antibody levels between the two cohorts. Participants 46-60years of age were significantly less likely to be seroprotected at day 21 than those 20-45years old in both cohorts. Immunogenicity of a half dose of adjuvanted pH1N1 influenza vaccine was adequate in subjects aged 20-45years. Dose reduction is a possible strategy for expanding the availability in the event of vaccine shortage in this age group.

Development of a collaborative program to provide extracorporeal membrane oxygenation for adults with refractory hypoxemia within the framework of a pandemic*

We report the process used to rapidly develop a collaborative adult respiratory extracorporeal membrane oxygenation program as a response to caring for young adult patients with refractory hypoxemia in the setting of the pH1N1 pandemic. Interdisciplinary response of a complex medical system to a public health crisis. PATIENTS, INTERVENTIONS, MEASUREMENTS, AND MAIN RESULTS: After the successful use of extracorporeal membrane oxygenation in young adults with pH1N1-induced acute respiratory distress syndrome refractory to conventional therapies, an adult venovenous extracorporeal membrane oxygenation program was implemented over an 8-wk period. Implementation of this program involved a number of key steps that were crucial in the development process, including administrative and institutional support, multidisciplinary leadership and collaboration, extensive interdisciplinary educational initiatives, and substantial technical modifications. In the setting of the pH1N1 influenza pandemic, an adult respiratory extracorporeal membrane oxygenation program was successfully developed to complement an established neonatal-pediatric program. This program expansion integrated all of the necessary components involved in the development process from start to finish and confirms that a healthcare system can respond very quickly and successfully to an urgent healthcare need.

Laboratory-confirmed pandemic H1N1 influenca in hospitalized adults – findings from the Canadian Nosocomial Infection Surveillance Program (CNISP), 2009-10

In response to the spread of the pandemic H1N1 (pH1N1) influenza virus in 2009, the Canadian Nosocomial Infection Surveillance Program (CNISP) extended its seasonal influenza surveillance to year-round reporting in order to describe the epidemiology and outcomes of pH1N1 in hospitalized adults. This report describes the findings of the surveillance program during the first year of pH1N1 influenza.

Effectiveness of pharmaceutical strategies for pandemic H1N1 2009 influenza in TAIWAN

Mass vaccination campaign conducted according to the priority groups, and provision of free rapid influenza diagnostic tests (RIDTs) and antivirals to predefined population at flu clinics, were implemented as a national program in Taiwan to reduce the impacts of the pandemic H1N1 2009 (pH1N1) influenza. This multi-center study aimed to evaluate the effectiveness of these pharmaceutical interventions based on hospital-wide influenza surveillance data.

Patients Hospitalized with pH1N1 Influenza in an Academic Community Medical Center

Background:The emergence of a novel strain of pandemic influenza (pH1N1) in 2009 presented significant challenges to health care facilities worldwide. In our academic community medical center in suburban Philadelphia, we noted our first pH1N1 diagnosis in September 2009. We sought to assess the impact of pH1N1 disease on our hospitalized patient population.Methods:We prospectively collected clinical and epidemiological data on 29 consecutive patients that were admitted to our hospital with a primary or secondary diagnosis of influenza from October 1-November 30, 2009. Data were obtained through care of the patients and chart review.Results:Prominent symptoms on admission included fever, hypoxia, cough, myalgias, and diarrhea, with leukocytosis and neutrophilia. Pre-existing medical conditions included asthma, pregnancy, immunosuppressive therapy, and sickle cell disease. All but 5 of the patients were under 60 years of age. Three patients had culture-documented bacterial or mycoplasma infections. All but two of the patients received oseltamivir. Six required admission to the intensive care unit but only one patient died.Conclusions:Our population of hospitalized patients with novel pH1N1 influenza demonstrated many of the features that have been associated with pH1N1 disease in other populations. Most of the patients were women and none of the patients died directly as a complication of influenza. We observed a cluster of patients with a tetrad of features comprising a history of asthma, obesity, female gender, and African-American race. Individuals with this constellation of factors should be specifically targeted for pH1N1 vaccination.