Medically Attended Acute Respiratory Illness Research Articles

Impact of Statins on Influenza Vaccine Effectiveness Against Medically Attended Acute Respiratory Illness.

Statins have antiinflammatory effects that may impact vaccine-induced immune responses. We investigated the impact of statin therapy on influenza vaccine effectiveness (VE) against medically attended acute respiratory illness (MAARI). We conducted a retrospective cohort study over nine influenza seasons using research databases of a large managed care organization in the United States. Influenza vaccination and statin prescription statuses of cohort members and MAARI cases were ascertained on a per-season basis. Incidence rate ratios (IRRs) of MAARI were estimated using Poisson regression and stratified by statin use. Using a ratio of ratios approach, we compared IRRs from periods during to IRRs from periods before influenza circulation and then used relative IRRs to compute VE. After adjustment for multiple prespecified covariates, the influenza VE against MAARI was lower among statin users than nonusers during periods of local (14.1% vs 22.9%; mean difference, 11.4%; 95% confidence interval [CI], -1.7% to 26.1%) and widespread (12.6% vs 26.2%; mean difference, 18.4%; 95% CI, 2.9%-36.2%) influenza circulation. In this study, statin therapy was associated with reduced influenza VE against MAARI. Since many cases of MAARI are not caused by influenza, studies of the impact of statins on influenza VE against laboratory-confirmed influenza are needed.

Influenza Outbreaks Among Passengers and Crew on Two Cruise Ships: A Recent Account of Preparedness and Response to an Ever-Present Challenge.

During spring 2014, two large influenza outbreaks occurred among cruise ship passengers and crew on trans-hemispheric itineraries. Passenger and crew information for both ships was obtained from components of the ship medical records. Data included demographics, diagnosis of influenza-like illness (ILI) or acute respiratory illness (ARI), illness onset date, passenger cabin number, crew occupation, influenza vaccination history, and rapid influenza diagnostic test (RIDT) result, if performed. In total, 3.7% of passengers and 3.1% of crew on Ship A had medically attended acute respiratory illness (MAARI). On Ship B, 6.2% of passengers and 4.7% of crew had MAARI. In both outbreaks, passengers reported illness prior to the ship's departure. Influenza activity was low in the places of origin of the majority of passengers and both ships' ports of call. The median age of affected passengers on both ships was 70 years. Diagnostic testing revealed three different co-circulating influenza viruses [influenza A(H1N1)pdm09, influenza A(H3N2), and influenza B] on Ship A and one circulating influenza virus (influenza B) on Ship B. Both ships voluntarily reported the outbreaks to the Centers for Disease Control and Prevention (CDC) and implemented outbreak response plans including isolation of sick individuals and antiviral treatment and prophylaxis. Influenza activity can become widespread during cruise ship outbreaks and can occur outside of traditional influenza seasons. Comprehensive outbreak prevention and control plans, including prompt antiviral treatment and prophylaxis, may mitigate the impact of influenza outbreaks on cruise ships.

Respiratory syncytial virus disease in preterm infants in the U.S. born at 32-35 weeks gestation not receiving immunoprophylaxis.

The Respiratory Syncytial Virus (RSV) Respiratory Events Among Preterm Infants Outcomes and Risk Tracking (REPORT) study evaluated RSV disease burden in U.S. preterm infants 32-35 weeks gestational age (wGA) not receiving RSV prophylaxis. Preterm infants <6 months of age as of November 1st were followed prospectively at 188 clinics from September to May 2009-2010 or 2010-2011. Nasal and pharyngeal swabs were collected for medically attended acute respiratory illnesses (MAARI) and tested for RSV by qRT-polymerase chain reaction. Risk factors were assessed using multivariate Cox proportional hazard model adjusted for seasonality. Of 1642 evaluable infants, 287 experienced RSV MAARI. Rates of RSV-related MAARI, outpatient lower respiratory tract illness, emergency department visits and hospitalization (RSVH) during November to March were 25.4, 13.7, 5.9 and 4.9 per 100 infant-seasons, respectively. Preschool-aged, nonmultiple-birth siblings and daycare attendance were consistently associated with increased risk of RSV. RSVH rates were highest in infants 32-34 and 35 wGA who were <6 months of age during November to March with daycare attendance or nonmultiple-birth, preschool-aged siblings (8.9 and 9.3 per 100 infant-seasons, respectively, versus 3.5 for all other infants, P<0.001). Chronologic age <3 months was associated with a higher RSVH rate for infants 35 wGA but not for infants 32-34 wGA. In US preterm infants who were 32-35 wGA, <6 months on November 1st and not receiving RSV prophylaxis, the burden of RSV MAARI was 25 per 100 infant-seasons. The highest RSVH rates occurred among those with daycare attendance or nonmultiple-birth, preschool-aged siblings while they were <6 months of age during the RSV season.

Surge in Hospitalizations Associated With Mechanical Ventilator Use During Influenza Outbreaks

Information on surges in critical care services including mechanical ventilator use during seasonal influenza outbreaks is limited. To potentially facilitate preparedness plans for future pandemics, we retrospectively quantitated surges in all-cause mechanical ventilator use during peak influenza for 12 consecutive years in all certified hospitals in Maryland. Influenza testing data obtained for the Centers for Disease Control and Protection, Health and Human Services region 3, included defined peak influenza outbreak periods (PIOP), non-influenza time periods (non-ITP), and proportions of circulating influenza types for all study years. Procedure codes for mechanical ventilator use and diagnostic codes for medically attended acute respiratory illness (MAARI) were reviewed for every Maryland hospitalization. Daily counts of hospitalizations associated with ventilator use or MAARI during PIOP compared to non-ITP were analyzed using Poisson regression adjusted for month and year. Ventilator use increased during PIOP by 7% (95% CI, 5-10) over non-ITP (P < .0001) for all study years. These annual surges correlated with influenza season intensity, as measured by MAARI-related hospitalizations (correlation coefficient = 0.91, P < .0001). Surges in ventilator use were temporally associated with PIOP and were positively correlated with influenza season intensity, as measured by hospitalizations associated with acute respiratory illness. This information may assist resource planning for future pandemics. (Disaster Med Public Health Preparedness. 2014;x:1-7).

Relationship of influenza vaccine match and use rate to medically attended acute respiratory illnesses in older residents of Maryland. November 13, 2012

The effectiveness of seasonal influenza vaccine may be influenced by mismatches to circulating influenza viruses. The relationship of these vaccine mismatches to the occurrence of medically attended acute respiratory illnesses (MAARI)-related emergency department (ED) visits and hospitalizations for all Maryland residents aged 50 years or older was examined for seven years (2001–2008). Also, relationships of individual circulating influenza types or subtypes to these MAARI-encounters were investigated.Anonymous, retrospective discharge data from all Maryland hospitals were utilized to determine daily numbers of MAARI-related ED visits and hospitalizations. Rate ratios (RR) of these MAARI-related encounters were then determined between intense influenza outbreak periods and non-influenza season time periods for each year using a Poisson regression model. Center for Disease Control end of season data reports were used to estimate each season's ‘match’ of each trivalent influenza vaccine component to subsequent circulating influenza viruses in the United States. The overall vaccine match proportion for the three vaccine viruses was then multiplied by reported vaccination rates of Maryland residents aged 50 years or older to determine an ‘estimated influenza vaccine impact factor’ (EIVIF) for each year. Correlation coefficients (CC) were then calculated comparing RR of MAARI-encounters to the corresponding EIVIF data. Finally, yearly RR of MAARI-encounters were compared to corresponding rates of individual circulating influenza types or subtypes circulating in the Maryland area.Consistent trends were observed whereby increased EIVIF proportions were correlated with decreased RR of MAARI-related ED visits and hospitalizations. This correlation reached statistical significance when comparing EIVIF to RR of MAARI-related ED visits (CC=−0.77, P=0.04). Also, the proportion of A/H3N2 viruses circulating each season was significantly positively correlated to that season's RR of MAARI-related ED visits (CC=0.89) and hospitalizations (CC=0.92); both P<0.01.Our data suggest increased protective effects of influenza immunization on reducing MAARI-related ED visits and hospitalizations in older individuals when the vaccine is well matched to the circulating strains. A/H3N2 viruses were clearly associated with more frequent MAARI-related ED visits and hospitalizations than A/H1N1 and B viruses.

The Relationship Between Influenza Outbreaks and Acute Ischemic Heart Disease in Maryland Residents Over a 7-Year Period

We sought to expand the understanding of relationships of influenza outbreaks to ischemic heart disease (IHD)-related events. Retrospective data sources were used to examine relationships of intense influenza outbreak periods (intense-IOP) to rates of IHD-related hospitalizations and deaths for Maryland residents aged ≥ 50 years. Rate ratios (RRs) were calculated for medical outcomes during intense-IOP compared to non-IOP for 7 years. RRs for IHD-related hospitalizations (RR=1.06), deaths (RR=1.16), and combined hospitalizations for IHD- and medically attended acute respiratory illness (MAARI) (RR=1.42) were significantly elevated during intense-IOP over the 7 years (P< .01). RRs for IHD-related hospitalizations increased significantly with age (P= .0007). Also, RRs for IHD-related hospitalizations each year were significantly correlated to proportions of circulating A/H3N2 viruses in that year (correlation coefficient [CC] =0.83, P= .02). Finally, for residents aged ≥ 65 years, RRs for IHD-related hospitalizations each year were significantly correlated with magnitude of the intense-IOPs in that year as measured by RRs for MAARI-related emergency department (ED) visits (CC=0.77, P= .04). These data suggest that influenza infections, particularly by A/H3N2 viruses, are directly associated with acute IHD-related events in older individuals.

Establishing the baseline burden of influenza in preparation for the evaluation of a countywide school-based influenza vaccination campaign

Background School-based influenza vaccination campaigns could mitigate the effects of influenza epidemics. A large countywide school-based vaccination campaign was launched in Knox County, Tennessee, in 2005. Assessment of campaign effects requires identification of appropriate control populations. We hypothesized that contiguous counties would share similar pre-campaign patterns of influenza activity. Methods We compared the burden of influenza emergency department (ED) visits and hospitalizations between Knox County (Knox) and eight counties surrounding Knox (Knox-surrounding) during five consecutive pre-campaign influenza seasons (2000–01 through 2004–05). Laboratory-defined influenza seasons were used to measure the weekly incidence of medically attended acute respiratory illnesses (MAARI) attributable to influenza in school-aged children 5–17 years old (campaign target) as well as in other age groups. Seasonal rates of MAARI attributable to influenza for Knox and Knox-surrounding counties were compared using rate ratios. Results During five consecutive influenza seasons, MAARI attributable to influenza showed synchronous temporal patterns in school-aged children from Knox and Knox-surrounding counties. The average seasonal rates of ED visits attributable to influenza were 12.37 (95% CI: 10.32–14.42) and 13.14 (95% CI: 11.23–15.05) per 1000, respectively. The respective average seasonal influenza hospitalization rates for Knox and Knox-surrounding were 0.38 (95% CI: 0–0.79) and 0.46 (95% CI: 0.07–0.85) per 1000 children. Rate ratio analyses indicated no significant differences in the incidence of MAARI attributable to influenza between school-aged children from Knox and Knox-surrounding counties. Estimates for other age groups showed similar patterns. Conclusion Before the Knox school-based influenza vaccination campaign, influenza resulted in an average of about 12 ED visits and 0.4 hospitalizations per 1000 school-aged children annually in Knox County. Since similar morbidity was observed in surrounding counties, they could serve as a control population for the assessment of the campaign effects.

Impact of influenza vaccination of schoolchildren on medical outcomes among all residents of Maryland

Special influenza vaccination programs of elementary school-aged children (ESAC) in some or all of Maryland Counties were conducted during the falls of 2005–2007. Rates of emergency department (E.D.) visits and hospitalizations for medically attended acute respiratory illnesses (MAARI) as well as deaths due to pneumonia and influenza for county residents were determined. The degree to which these rates were modulated during intense influenza outbreak periods (IIOP) in counties who vaccinated a greater percentage of ESAC was estimated using Poisson regression. Notably, for every 20% increase in vaccination rates, MAARI related E.D. visits during IIOP decreased by 8% (95% C.I., 5–12%) in children aged 5–11 years and by 6% (95% C.I., 3–8%) in adults aged 19–49 years ( p < 0.001), which suggests both a direct and indirect benefit of the vaccination programs. In contrast, MAARI related hospitalizations increased during IIOP by 4% (95% C.I., 3–9%) in adults aged >50 years for every 20% increase in vaccination rates ( p < 0.023) for which we have no plausible biologic explanation. No significant changes in deaths were noted.

Safety of the Intranasal, Trivalent, Live Attenuated Influenza Vaccine (LAIV) in Children With Intermittent Wheezing in an Open-Label Field Trial

Background: Safety of the intranasal, trivalent, live attenuated influenza vaccine (LAIV) in children with asthma is unknown. A previous report showed an “asthma signal” in children aged 18–35 months. Methods: Healthy children aged 1.5–18 years with history of intermittent wheezing received single annual LAIV doses during a 4-year trial. Rates of medically-attended acute respiratory illnesses, including acute asthma exacerbation, during 0–14 and 0–42 days post-LAIV were compared with respective reference periods (before day 0 and after 14 or 42 days). To assess the risk of new-onset asthma, LAIV recipients without history of wheezing were analyzed. Results: During each of the 4 years, 454, 656, 656, and 430 children, respectively, with intermittent wheezing who received LAIV had no increased risk for medically-attended acute respiratory illnesses, including asthma exacerbation. First-dose LAIV recipients, including those aged 1.5–4 years, and those receiving 2–4 consecutive annual doses had no increased risk. Children with parents' report of intermittent wheezing and those with administrative database codes for asthma during 2 prior years had no increased risk. During the 4 years, 2952, 3092, 2953, and 2478 children without history of wheezing had no increased risk of new-onset asthma. Conclusions: LAIV administration in children aged 1.5–18 years with history of intermittent wheezing was safe, and was not associated with increased risk for medically-attended acute respiratory illnesses, including acute asthma exacerbation. This was true for the first and 2–4 consecutive annual doses. Parents' report of intermittent wheezing was reliable. First-dose LAIV was not associated with new-onset asthma in children without history of wheezing.

LAIV Effective in Children During an Outbreak of a Drifted Strain

Infectious Diseases| November 01 2007 LAIV Effective in Children During an Outbreak of a Drifted Strain AAP Grand Rounds (2007) 18 (5): 57. https://doi.org/10.1542/gr.18-5-57 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Cite Icon Cite Search Site Citation LAIV Effective in Children During an Outbreak of a Drifted Strain. AAP Grand Rounds November 2007; 18 (5): 57. https://doi.org/10.1542/gr.18-5-57 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search toolbar search search input Search input auto suggest filter your search All PublicationsAll JournalsAAP Grand RoundsPediatricsHospital PediatricsPediatrics In ReviewNeoReviewsAAP NewsAll AAP Sites Search Advanced Search Topics: disease outbreaks, influenza, influenza vaccine, trivalent live attenuated, vaccines Source: Piedra PA, Gaglani MJ, Kozinetz CJ, et al. Trivalent live attenuated intranasal influenza vaccine administered during the 2003–2004 Influenza Type A (H3N2) outbreak provided immediate, direct, and indirect protection in children. Pediatrics. 2007;120(3):e553–e564; doi:10.1542/peds.2006–2836 Since 1998 investigators from Baylor College of Medicine, Houston, and Scott and White Clinic and Hospital and Health Plan, Temple, Texas, have been conducting an open label, non-randomized, community-based influenza vaccine trial in school children five to 18 years of age. For the 2003–2004 influenza season, eligible healthy children were given intranasal trivalent live attenuated influenza vaccine (LAIV-T), while those with underlying health conditions were given injected trivalent inactivated influenza vaccine (TIV). LAIV-T and TIV were administered in the intervention communities and TIV was given in the comparison communities, chosen because these communities were demographically similar and in close proximity, with the expectation that this would likely result in the same strain of influenza circulating in both areas and with similar temporal influenza outbreaks. Children eligible for either influenza vaccine who were not participating in the study could receive the vaccines from their providers as part of their routine care. Shortly after initiating immunizations, an early outbreak of influenza due to a drifted strain occurred between October and December 2003. Investigators took advantage of this unexpected event to determine the effectiveness of LAIV-T and TIV during an influenza outbreak when the dominant circulating strain was antigenically distinct from the vaccine strains. Main study outcomes included office visits for physician-diagnosed cases of pneumonia and influenza (P&I) and for medically attended acute respiratory illness (MAARI). Direct evidence of vaccine efficacy was evaluated by comparing age-specific rates for these outcomes among vaccine recipients and those who weren’t vaccinated in the intervention communities. Indirect evidence of efficacy was assessed by comparing age-specific MAARI rates in the intervention and comparison communities. Rates were compared before, during, and after the influenza outbreak. A total of 4,961 children who lived in the intervention communities received LAIV-T and 1,944 received TIV. Of the 897 children five through eight years of age eligible for a second dose of LAIV-T, only 163 (18.2%) received a second dose (75 received it on or after the last day of the outbreak). Of the 737 children of the same age group who received TIV, the number eligible for a second dose of TIV was not known; however, 36 received a second dose (eight on or after the last day of the outbreak). Approximately 58% of the first doses had been administered when the epidemic reached its peak. The influenza immunization coverage in the intervention communities was estimated to be approximately 31%. Age-specific influenza vaccine coverage was also estimated in both the intervention and comparison communities. The overall coverage with TIV was similar in the intervention (27.5%) and comparison communities (28.8%). However, the rate of use in the intervention communities was significantly higher in children under five years of age (28.5% vs 23.6%) and adults ≥65 years of age (61.4% vs 57.6%). In the... You do not currently have access to this content.

Efficacy of trivalent, cold-adapted, influenza virus vaccine against influenza A (Fujian), a drift variant, during 2003–2004

In the 2003–2004 influenza season, the predominant circulating influenza A (H3N2) virus in the United States was similar antigenically to A/Fujian/411/2002 (H3N2), a drift variant of A/Panama/2007/99 (H3N2), the vaccine strain. That year, a field study of trivalent live-attenuated influenza vaccine (LAIV-T) was conducted in Temple-Belton, Texas, as part of a larger community-based, non-randomized, open-label study in three communities that began in August 1998 [Gaglani MJ, Piedra PA, Herschler GB, Griffith ME, Kozinetz CA, Riggs MW, et al. Direct effectiveness of the trivalent, cold-adapted, influenza virus vaccine (CAIV-T) against the 2000–2001 influenza A (H1N1) and B epidemic in healthy children. Arch Pediatr Adolesc Med 2004;158:65–73; Piedra PA, Gaglani MJ, Kozinetz CA, Herschler G, Riggs M, Griffith M, et al. Herd immunity in adults against influenza-related illnesses with use of the trivalent-live attenuated influenza vaccine (CAIV-T) in children. Vaccine 2005;23:1540–8; Piedra PA, Gaglani MJ, Riggs M, Herschler G, Fewlass C, Watts M, et al. Live attenuated influenza vaccine, trivalent, is safe in healthy children 18 months to 4 years, 5 to 9 years, and 10 to 18 years of age in a community-based, nonrandomized, open-label trial. Pediatrics 2005;116:397–407]. Participants were healthy children aged 5–18 years. The analysis here concerns 6403 children in the Scott & White Health Plan (SWHP) database living within zip codes of the Temple-Belton area, of whom 1706 received LAIV-T and 548 received trivalent inactivated vaccine (TIV) in 2003, 983 had been previously vaccinated in 1998–2001, but not in 2002–2003 or 2003, and 3166 had never been vaccinated. The main outcome measure was medically-attended acute respiratory illness (MAARI). Surveillance culture results were incorporated into the analysis to estimate efficacy against culture-confirmed influenza illness. Vaccine effectiveness of LAIV-T against MAARI was 26% (95% confidence interval (CI) 11, 39). Vaccine efficacy of LAIV-T against culture-confirmed influenza illness including surveillance cultures of children in the SWHP database in the validation calculation was 56% (95% CI 24, 84). LAIV-T was cross-protective with a drift variant strain in 2003–2004, evidence that such vaccines could be important for preparing for a pandemic and for annual influenza.

Live Attenuated Influenza Vaccine, Trivalent, Is Safe in Healthy Children 18 Months to 4 Years, 5 to 9 Years, and 10 to 18 Years of Age in a Community-Based, Nonrandomized, Open-Label Trial

Live Attenuated Influenza Vaccine, Trivalent, Is Safe in Healthy Children 18 Months to 4 Years, 5 to 9 Years, and 10 to 18 Years of Age in a Community-Based, Nonrandomized, Open-Label Trial

Herd immunity in adults against influenza-related illnesses with use of the trivalent-live attenuated influenza vaccine (CAIV-T) in children

Highest attack rates for influenza occur in children. Immunization of schoolchildren with inactivated influenza vaccine in Michigan and Japan was associated with decreased morbidity and mortality, respectively, in older community contacts. An open-labeled, non-randomized, community-based trial in children with the cold adapted influenza vaccine, trivalent (CAIV-T) was initiated to determine the coverage necessary to reduce spread of influenza in the community. Age-specific baseline rates of medically attended acute respiratory illness (MAARI) for Scott and White Health Plan (SWHP) members at intervention (Temple and Belton) and comparison communities (Waco, Bryan, and College Station) were obtained in 1997–1998. During three subsequent vaccination years, 4298, 5251 and 5150 children received one dose per season of CAIV-T. Vaccinees represented 20–25% of the age-eligible children. Age-specific MAARI rates were compared for SWHP members in the intervention and comparison sites during the influenza outbreaks. Baseline age-specific MAARI rates per 100 persons for the influenza season were comparable between the intervention and comparison communities. In the subsequent three influenza seasons, the age groups 35–44, 45–54, 55–65 and >64 years experienced reductions in MAARI rates in the intervention communities. In adults ≥35 years of age, significant reductions in MAARI of 0.08 (95% CI: 0.04, 0.13), 0.18 (95% CI: 0.14, 0.22) and 0.15 (95% CI: 0.12, 0.19), were observed in the influenza seasons for vaccination years 1, 2 and 3, respectively. No consistent reduction in MAARI rates was detected in the younger age groups. Vaccination of approximately 20–25% of children, 1.5–18 years of age in the intervention communities resulted in an indirect protection of 8–18% against MAARI in adults ≥35 years of age.

Estimating efficacy of trivalent, cold-adapted, influenza virus vaccine (CAIV-T) against influenza A (H1N1) and B using surveillance cultures.

The authors report on a community-based, nonrandomized, open-label study, conducted during the 2000-2001 influenza season in Temple-Belton, Texas, of the protective effectiveness of trivalent, cold-adapted, influenza virus vaccine (CAIV-T) in children aged 18 months-18 years. The dominant circulating strains in 2000-2001 were influenza A/New Caledonia/20/99 (H1N1) and influenza B/Sichuan/379/99. Children had access to CAIV-T during the 1998-1999, 1999-2000, and 2000-2001 influenza seasons. The vaccine included influenza A/Sydney/5/97 (H3N2) and B/Beijing/184/93-like (B/Ann Arbor/l/94) strains in all three seasons. The vaccine included A/Beijing/262/95 (H1N1) in 1998-1999 and 1999-2000, which was replaced by A/New Caledonia/20/99 (H1N1) in 2000-2001. When medically attended acute respiratory illness (MAARI) was used as the outcome, the protective effectiveness for children vaccinated in 2000 was 18% (95% confidence interval (CI): 11, 25). Based on a combination of a validation sample of surveillance cultures and the MAARI outcome, protective efficacy against combined influenza A (H1N1) and B was 79% (95% CI: 51, 91). The efficacy estimate, after accounting for missing influenza culture status, against influenza A (H1N1) alone was 92% (95% CI: 42, 99) and against a new variant of influenza B alone was 66% (95% CI: 9, 87). CAIV-T provides substantial protection against a mixture of influenza A (H1N1) and B. Results demonstrate the powerful potential of using validation sets for outcomes in vaccine field studies.

Safety and effectiveness of the trivalent, cold-adapted influenza vaccine (CAIV-T) in children

Background: We report on the safety and effectiveness of trivalent, cold-adapted influenza vaccine (CAIV-T) in children in the largest community trial to date. Methods: Enrolled children 18 months through 18 years of age received CAIV-T in years 1 (1998) and 2 (1999). All were surveyed for serious adverse events (SAEs). The relative risk (RR) of medically attended acute respiratory illness (MAARI) was estimated in the first 14 days after CAIV-T and compared to the reference interval pre-vaccine and >14 days after CAIV-T. Vaccine effectiveness against MAARI during the influenza outbreak was determined for vaccinees compared to age-eligible non-participants. Results: 4298 and 5250 children received CAIV-T in years 1 and 2. Twenty-two SAEs were identified; none were vaccine associated. No excess MAARI attributed to CAIV-T was observed: the RRs 0–14 days after CAIV-T were 1.0 (95% CI 0.8–1.3) and 1.1 (95% CI 0.8–1.4) for years 1 and 2, respectively. Similar safety was seen in a subgroup of children with mild wheezing illness. In year 1, vaccine effectiveness was detected during the intense period of the influenza season: RR 0.9 (95% CI: 0.81–0.99); year 2 is pending. Conclusions: CAIV-T was safe in children including those with mild wheezing illness. Effectiveness of CAIV-T was detected against MAARI.