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Background: In contrast with respiratory disease caused by influenza, information on the risk of respiratory syncytial virus (RSV) disease among adults with chronic medical conditions (CMCs) is limited., Methods: We linked population-based surveillance of acute respiratory illness hospitalizations to national administrative data to estimate seasonal RSV hospitalization rates among adults aged 18-80 years with the following preexisting CMCs: chronic obstructive pulmonary disease (COPD), asthma, congestive heart failure (CHF), coronary artery disease (CAD), cerebrovascular accidents (CVA), diabetes mellitus (DM), and end-stage renal disease (ESRD). Age- and ethnicity-adjusted rates stratified by age group were estimated., Results: Among 883 999 adult residents aged 18-80 years, 281 RSV-positive hospitalizations were detected during 2012-2015 winter seasons. Across all ages, RSV hospitalization rates were significantly higher among adults with COPD, asthma, CHF, and CAD compared with those without each corresponding condition. RSV hospitalization rates were significantly higher among adults with ESRD aged 50-64 years and adults with DM aged 18-49 years and 65-80 years compared with adults in each age group without these conditions. No increased risk was seen for adults with CVA. The CMC with the highest risk of RSV hospitalization was CHF (incidence rate ratio [IRR] range, 4.6-36.5 across age strata) and COPD (IRR range, 9.6-9.7). Among RSV-positive adults, CHF and COPD were independently associated with increased length of hospital stay., Conclusions: Adults with specific CMCs are at increased risk of RSV hospitalizations. Age affects this relationship for some CMCs. Such populations maybe relevant for future RSV prevention strategies., (© The Author(s) 2020. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.)

Background: Severe influenza illness is presumed more common in adults with chronic medical conditions (CMCs), but evidence is sparse and often combined into broad CMC categories., Methods: Residents (aged 18-80 years) of Central and South Auckland hospitalized for World Health Organization-defined severe acute respiratory illness (SARI) (2012-2015) underwent influenza virus polymerase chain reaction testing. The CMC statuses for Auckland residents were modeled using hospitalization International Classification of Diseases, Tenth Revision codes, pharmaceutical claims, and laboratory results. Population-level influenza rates in adults with congestive heart failure (CHF), coronary artery disease (CAD), cerebrovascular accidents (CVA), chronic obstructive pulmonary disease (COPD), asthma, diabetes mellitus (DM), and end-stage renal disease (ESRD) were calculated by Poisson regression stratified by age and adjusted for ethnicity., Results: Among 891 276 adults, 2435 influenza-associated SARI hospitalizations occurred. Rates were significantly higher in those with CMCs compared with those without the respective CMC, except for older adults with DM or those aged <65 years with CVA. The largest effects occurred with CHF (incidence rate ratio [IRR] range, 4.84-13.4 across age strata), ESRD (IRR range, 3.30-9.02), CAD (IRR range, 2.77-10.7), and COPD (IRR range, 5.89-8.78) and tapered with age., Conclusions: Our findings support the increased risk of severe, laboratory-confirmed influenza disease among adults with specific CMCs compared with those without these conditions., (© The Author(s) 2019. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.)

Background: Pregnant women are prioritized for seasonal influenza vaccination, but the evidence on the risk of influenza during pregnancy that is used to inform these policies is limited., Methods: Individual-level administrative data sets and active surveillance data were joined to estimate influenza-associated hospitalization and outpatient visit rates by pregnancy, postpartum, and trimester status., Results: During 2012-2015, 46 of 260 (17.7%) influenza-confirmed hospitalizations for acute respiratory infection and 13 of 294 (4.4%) influenza-confirmed outpatient visits were among pregnant and postpartum women. Pregnant and postpartum women experienced higher rates of influenza-associated hospitalization than nonpregnant women overall (rate ratio [RR], 3.4; 95% confidence interval [CI], 2.5-4.7) and by trimester (first, 2.5 [95% CI, 1.2-5.4]; second, 3.9 [95% CI, 2.4-6.3]; and third, 4.8 [95% CI, 3.0-7.7]); the RR for the postpartum period was 0.7 (95% CI, 3.0-7.7). Influenza A viruses were associated with an increased risk (RR for 2009 pandemic influenza A[H1N1] virus, 5.3 [95% CI, 3.2-8.7]; RR for influenza A(H3N2) virus, 3.0 [95% CI, 1.8-5.0]), but influenza B virus was not (RR, 1.8; 95% CI, .7-4.6). Influenza-associated hospitalization rates in pregnancy were significantly higher for Māori women (RR, 3.2; 95% CI, 1.3-8.4), compared with women of European or other ethnicity. Similar risks for influenza-confirmed outpatient visits were not observed., Conclusion: Seasonal influenza poses higher risks of hospitalization among pregnant women in all trimesters, compared with nonpregnant women. Hospitalization rates vary by influenza virus type and ethnicity among pregnant women., (© The Author(s) 2019. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.)

Background: Understanding the attack rate of influenza infection and the proportion who become ill by risk group is key to implementing prevention measures. While population-based studies of antihemagglutinin antibody responses have been described previously, studies examining both antihemagglutinin and antineuraminidase antibodies are lacking., Methods: In 2015, we conducted a seroepidemiologic cohort study of individuals randomly selected from a population in New Zealand. We tested paired sera for hemagglutination inhibition (HAI) or neuraminidase inhibition (NAI) titers for seroconversion. We followed participants weekly and performed influenza polymerase chain reaction (PCR) for those reporting influenza-like illness (ILI)., Results: Influenza infection (either HAI or NAI seroconversion) was found in 321 (35% [95% confidence interval, 32%-38%]) of 911 unvaccinated participants, of whom 100 (31%) seroconverted to NAI alone. Young children and Pacific peoples experienced the highest influenza infection attack rates, but overall only a quarter of all infected reported influenza PCR-confirmed ILI, and one-quarter of these sought medical attention. Seroconversion to NAI alone was higher among children aged <5 years vs those aged ≥5 years (14% vs 4%; P < .001) and among those with influenza B vs A(H3N2) virus infections (7% vs 0.3%; P < .001)., Conclusions: Measurement of antineuraminidase antibodies in addition to antihemagglutinin antibodies may be important in capturing the true influenza infection rates.

Background: The immunologic factors underlying severe influenza are poorly understood. To address this, we compared the immune responses of influenza-confirmed hospitalized individuals with severe acute respiratory illness (SARI) to those of nonhospitalized individuals with influenza-like illness (ILI)., Methods: Peripheral blood lymphocytes were collected from 27 patients with ILI and 27 with SARI, at time of enrollment and then 2 weeks later. Innate and adaptive cellular immune responses were assessed by flow cytometry, and serum cytokine levels were assessed by a bead-based assay., Results: During the acute phase, SARI was associated with significantly reduced numbers of circulating myeloid dendritic cells, CD192+ monocytes, and influenza virus-specific CD8+ and CD4+ T cells as compared to ILI. By the convalescent phase, however, most SARI cases displayed continued immune activation characterized by increased numbers of CD16+ monocytes and proliferating, and influenza virus-specific, CD8+ T cells as compared to ILI cases. SARI was also associated with reduced amounts of cytokines that regulate T-cell responses (ie, interleukin 4, interleukin 13, interleukin 12, interleukin 10, and tumor necrosis factor β) and hematopoiesis (interleukin 3 and granulocyte-macrophage colony-stimulating factor) but increased amounts of a proinflammatory cytokine (tumor necrosis factor α), chemotactic cytokines (MDC, MCP-1, GRO, and fractalkine), and growth-promoting cytokines (PDGFBB/AA, VEGF, and EGF) as compared to ILI., Conclusions: Severe influenza cases showed a delay in the peripheral immune activation that likely led prolonged inflammation, compared with mild influenza cases., (© The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.)

Objectives: In 2007 New Zealand (NZ) became the first country to make oseltamivir (Tamiflu®) available off-prescription. This study investigated the extent of pharmacist supply of oseltamivir over 5 years, including during the influenza A(H1N1) pandemic, and the impact of pharmacist supply of oseltamivir on influenza virus oseltamivir susceptibility, personal stockpiling and influenza vaccine uptake., Methods: Randomly selected community pharmacies in NZ reported oseltamivir provision by prescription and through pharmacist supply from 1 January 2007 to 15 September 2011. Oseltamivir resistance data on influenza viruses isolated during influenza surveillance from 2008 to 2011 were obtained, along with influenza vaccine uptake data from 2005 to 2011 and influenza detection data., Results: Seventy of 85 eligible pharmacies completed the study (82% response rate). Most supplies of oseltamivir throughout the 5 years were dispensed against a prescription rather than pharmacist supplied, with pharmacist supply responsible for 11% of supplies during the pandemic years (2009-10) versus 27% and 31% during 2007 and 2008, respectively. Pharmacist-supplied oseltamivir did not appear to be associated with the development of resistance, with identified likely stockpiling or with a decline in influenza immunization. Pharmacist supplies largely matched the timing of influenza in the community and peaked in June 2009, as did prescription supplies., Conclusions: Five years of non-prescription oseltamivir in NZ has resulted in no significant change in the development of resistance or rates of influenza immunization. Supplies remained modest and significant consumer stockpiling through pharmacist supply has not occurred, even during the influenza A(H1N1)pdm09 pandemic in 2009 and 2010. Pharmacists could be better utilized in ensuring fast distribution of antivirals to influenza sufferers during a pandemic.

In 2001, increased activity of the rarely detected enterovirus echovirus type 13 (E13) was observed in the United States. This article describes the epidemiologic, clinical, and genetic characteristics of E13 activity in the United States in 2001, compared with E13 activity abroad in 2000-2002. In the United States, E13 accounted for 376 (24%) of the 1584 enterovirus isolates reported in 2001 (29% of the reported isolates had a known serotype), compared with 74 isolates reported during 1970-2000. Five states reported aseptic meningitis outbreaks associated with E13, for a total of 521 cases. All characterized E13 isolates from the United States, Europe, Asia, and Oceania recovered in 2000-2002 were at least 95% identical to each other in VP1 capsid gene sequence, but they were genetically distinct from E13 isolates recovered before 2000. Continued surveillance of enteroviruses is important to alert physicians and public health officials to changes in disease trends and to improve efficiencies of clinical intervention.

Echovirus type 33 (E33) is a relatively uncommon enterovirus. An E33 outbreak during the winter of 2000 in New Zealand led to 75 virologically-confirmed cases of E33 infection (2.6 cases per 100,000 individuals). Sixty-six (88%) of the 75 patients were aged <30 years, with the highest rates of infection recorded in Maori and Pacific ethnic groups. Overall, 47 (84%) of 56 patients whose cases were analyzed had either aseptic meningitis or encephalitis. Central nervous system involvement was more common after infancy (43 of 45 non-infant patients vs. 4 of 11 infants [relative risk, 2.6; 95% CI, 1.5-4.3]). Two infants died, including a neonate with fulminant hepatitis. Independent of symptom duration, neutrophil-predominant pleocytosis was detected in 17 (41%) of 41 cerebrospinal fluid specimens. Virus isolates could not be definitively typed by antibody neutralization testing but were identified as E33 by partial sequencing of the VP-1 capsid gene. The isolates were closely related to strains from Australia and Oman. Molecular typing, together with a serotype-specific E33 PCR, improved the speed and effectiveness of the outbreak investigation.