RESUMEN
The Canadian Sentinel Practitioner Surveillance Network reports mid-season 2023/24 influenza vaccine effectiveness (VE) of 63% (95%â¯CI: 51-72) against influenza A(H1N1)pdm09, lower for clade 5a.2a.1 (56%; 95%â¯CI: 33-71) than clade 5a.2a (67%; 95%â¯CI: 48-80), and lowest against influenza A(H3N2) (40%; 95%â¯CI: 5-61). The Omicron XBB.1.5 vaccine protected comparably well, with VE of 47% (95%â¯CI: 21-65) against medically attended COVID-19, higher among people reporting a prior confirmed SARS-CoV-2 infection at 67% (95%â¯CI: 28-85).
Asunto(s)
COVID-19 , Subtipo H1N1 del Virus de la Influenza A , Vacunas contra la Influenza , Gripe Humana , Humanos , Gripe Humana/epidemiología , Gripe Humana/prevención & control , Estaciones del Año , Subtipo H3N2 del Virus de la Influenza A/genética , Eficacia de las Vacunas , Canadá/epidemiología , Vigilancia de Guardia , Vacunación , Estudios de Casos y ControlesRESUMEN
BACKGROUND: Population-based cross-sectional serosurveys within the Lower Mainland, British Columbia, Canada, showed about 10%, 40% and 60% of residents were infected with SARS-CoV-2 by the sixth (September 2021), seventh (March 2022) and eighth (July 2022) serosurveys. We conducted the ninth (December 2022) and tenth (July 2023) serosurveys and sought to assess risk of severe outcomes from a first-ever SARS-CoV-2 infection during intersurvey periods. METHODS: Using increments in cumulative infection-induced seroprevalence, population census, discharge abstract and vital statistics data sets, we estimated infection hospitalization and fatality ratios (IHRs and IFRs) by age and sex for the sixth to seventh (Delta/Omicron-BA.1), seventh to eighth (Omicron-BA.2/BA.5) and eighth to ninth (Omicron-BA.5/BQ.1) intersurvey periods. As derived, IHR and IFR estimates represent the risk of severe outcome from a first-ever SARS-CoV-2 infection acquired during the specified intersurvey period. RESULTS: The cumulative infection-induced seroprevalence was 74% by December 2022 and 79% by July 2023, exceeding 80% among adults younger than 50 years but remaining less than 60% among those aged 80 years and older. Period-specific IHR and IFR estimates were consistently less than 0.3% and 0.1% overall. By age group, IHR and IFR estimates were less than 1.0% and up to 0.1%, respectively, except among adults aged 70-79 years during the sixth to seventh intersurvey period (IHR 3.3% and IFR 1.0%) and among those aged 80 years and older during all periods (IHR 4.7%, 2.2% and 3.5%; IFR 3.3%, 0.6% and 1.3% during the sixth to seventh, seventh to eighth and eighth to ninth periods, respectively). The risk of severe outcome followed a J-shaped age pattern. During the eighth to ninth period, we estimated about 1 hospital admission for COVID-19 per 300 newly infected children younger than 5 years versus about 1 per 30 newly infected adults aged 80 years and older, with no deaths from COVID-19 among children but about 1 death per 80 newly infected adults aged 80 years and older during that period. INTERPRETATION: By July 2023, we estimated about 80% of residents in the Lower Mainland, BC, had been infected with SARS-CoV-2 overall, with low risk of hospital admission or death; about 40% of the oldest adults, however, remained uninfected and at highest risk of a severe outcome. First infections among older adults may still contribute substantial burden from COVID-19, reinforcing the need to continue to prioritize this age group for vaccination and to consider them in health care system planning.
Asunto(s)
COVID-19 , Niño , Humanos , Anciano , Preescolar , Recién Nacido , Colombia Británica/epidemiología , Estudios Transversales , Estudios Seroepidemiológicos , COVID-19/epidemiología , SARS-CoV-2 , Hospitalización , HospitalesRESUMEN
The Canadian Sentinel Practitioner Surveillance Network estimated vaccine effectiveness (VE) during the unusually early 2022/23 influenza A(H3N2) epidemic. Like vaccine, circulating viruses were clade 3C.2a1b.2a.2, but with genetic diversity affecting haemagglutinin positions 135 and 156, and reassortment such that H156 viruses acquired neuraminidase from clade 3C.2a1b.1a. Vaccine provided substantial protection with A(H3N2) VE of 54% (95% CI: 38 to 66) overall. VE was similar against H156 and vaccine-like S156 viruses, but with potential variation based on diversity at position 135.
Asunto(s)
Vacunas contra la Influenza , Gripe Humana , Humanos , Gripe Humana/epidemiología , Gripe Humana/prevención & control , Subtipo H3N2 del Virus de la Influenza A , Estaciones del Año , Eficacia de las Vacunas , Canadá/epidemiología , Variación GenéticaRESUMEN
BACKGROUND: The influenza A(H3N2) vaccine was updated from clade 3C.3a in 2015-2016 to 3C.2a for 2016-2017 and 2017-2018. Circulating 3C.2a viruses showed considerable hemagglutinin glycoprotein diversification and the egg-adapted vaccine also bore mutations. METHODS: Vaccine effectiveness (VE) in 2016-2017 and 2017-2018 was assessed by test-negative design, explored by A(H3N2) phylogenetic subcluster and prior season's vaccination history. RESULTS: In 2016-2017, A(H3N2) VE was 36% (95% confidence interval [CI], 18%-50%), comparable with (43%; 95% CI, 24%-58%) or without (33%; 95% CI, -21% to 62%) prior season's vaccination. In 2017-2018, VE was 14% (95% CI, -8% to 31%), lower with (9%; 95% CI, -18% to 30%) versus without (45%; 95% CI, -7% to 71%) prior season's vaccination. In 2016-2017, VE against predominant clade 3C.2a1 viruses was 33% (95% CI, 11%-50%): 18% (95% CI, -40% to 52%) for 3C.2a1a defined by a pivotal T135K loss of glycosylation; 60% (95% CI, 19%-81%) for 3C.2a1b (without T135K); and 31% (95% CI, 2%-51%) for other 3C.2a1 variants (with/without T135K). VE against 3C.2a2 viruses was 45% (95% CI, 2%-70%) in 2016-2017 but 15% (95% CI, -7% to 33%) in 2017-2018 when 3C.2a2 predominated. VE against 3C.2a1b in 2017-2018 was 37% (95% CI, -57% to 75%), lower at 12% (95% CI, -129% to 67%) for a new 3C.2a1b subcluster (n = 28) also bearing T135K. CONCLUSIONS: Exploring VE by phylogenetic subcluster and prior vaccination history reveals informative heterogeneity. Pivotal mutations affecting glycosylation sites, and repeat vaccination using unchanged antigen, may reduce VE.
Asunto(s)
Epidemias , Vacunas contra la Influenza , Gripe Humana , Humanos , Gripe Humana/epidemiología , Gripe Humana/prevención & control , Subtipo H3N2 del Virus de la Influenza A , Filogenia , Eficacia de las Vacunas , Vacunación , Canadá/epidemiología , Estaciones del AñoRESUMEN
BACKGROUND: The evolving proportion of the population considered immunologically naive versus primed for more efficient immune memory response to SARS-CoV-2 has implications for risk assessment. We sought to chronicle vaccine- and infection-induced seroprevalence across the first 7 waves of the COVID-19 pandemic in British Columbia, Canada. METHODS: During 8 cross-sectional serosurveys conducted between March 2020 and August 2022, we obtained anonymized residual sera from children and adults who attended an outpatient laboratory network in the Lower Mainland (Greater Vancouver and Fraser Valley). We used at least 3 immunoassays per serosurvey to detect SARS-CoV-2 spike and nucleocapsid antibodies. We assessed any seroprevalence (vaccineor infection-induced, or both), defined by positivity on any 2 assays, and infection-induced seroprevalence, also defined by dual-assay positivity but requiring both antinucleocapsid and antispike detection. We used estimates of infection-induced seroprevalence to explore underascertainment of infections by surveillance case reports. RESULTS: By January 2021, we estimated that any seroprevalence remained less than 5%, increasing with vaccine rollout to 56% by May-June 2021, 83% by September-October 2021 and 95% by March 2022. Infection-induced seroprevalence remained less than 15% through September-October 2021, increasing across Omicron waves to 42% by March 2022 and 61% by July-August 2022. By August 2022, 70%-80% of children younger than 20 years and 60%-70% of adults aged 20-59 years had been infected, but fewer than half of adults aged 60 years and older had been infected. Compared with estimates of infection-induced seroprevalence, surveillance case reports underestimated infections 12-fold between September 2021 and March 2022 and 92-fold between March 2022 and August 2022. INTERPRETATION: By August 2022, most children and adults younger than 60 years had evidence of both SARS-CoV-2 vaccination and infection. As previous evidence suggests that a history of both exposures may induce stronger, more durable hybrid immunity than either exposure alone, older adults - who have the lowest infection rates but highest risk of severe outcomes - continue to warrant prioritized vaccination.
Asunto(s)
COVID-19 , Vacunas , Niño , Humanos , Persona de Mediana Edad , Anciano , SARS-CoV-2 , Estudios Seroepidemiológicos , Vacunas contra la COVID-19 , Estudios Transversales , Pandemias/prevención & control , COVID-19/epidemiología , COVID-19/prevención & control , Colombia Británica/epidemiología , Anticuerpos AntiviralesRESUMEN
Influenza virus circulation virtually ceased in Canada during the COVID-19 pandemic, re-emerging with the relaxation of restrictions in spring 2022. Using a test-negative design, the Canadian Sentinel Practitioner Surveillance Network reports 2021/22 vaccine effectiveness of 36% (95%â¯CI: -38 to 71) against late-season illness due to influenza A(H3N2) clade 3C.2a1b.2a.2 viruses, considered antigenically distinct from the 3C.2a1b.2a.1 vaccine strain. Findings reinforce the World Health Organization's decision to update the 2022/23 northern hemisphere vaccine to a more representative A(H3N2) clade 3C.2a1b.2a.2 strain.
Asunto(s)
COVID-19 , Vacunas contra la Influenza , Gripe Humana , Canadá/epidemiología , Humanos , Subtipo H3N2 del Virus de la Influenza A , Gripe Humana/epidemiología , Gripe Humana/prevención & control , Pandemias/prevención & control , Eficacia de las VacunasRESUMEN
Influenza vaccine effectiveness against influenza and noninfluenza respiratory viruses (NIRVs) was assessed by test-negative design using historic datasets of the community-based Canadian Sentinel Practitioner Surveillance Network, spanning 2010-2011 to 2016-2017. Vaccine significantly reduced the risk of influenza illness by >40% with no effect on coronaviruses or other NIRV risk.
Asunto(s)
Infecciones por Coronavirus/epidemiología , Vacunas contra la Influenza/inmunología , Gripe Humana/prevención & control , Infecciones del Sistema Respiratorio/virología , Adolescente , Adulto , Anciano , Canadá/epidemiología , Estudios de Casos y Controles , Niño , Preescolar , Infecciones por Coronavirus/etiología , Femenino , Humanos , Inmunogenicidad Vacunal , Lactante , Vacunas contra la Influenza/administración & dosificación , Gripe Humana/epidemiología , Masculino , Persona de Mediana Edad , Infecciones del Sistema Respiratorio/prevención & control , Estudios Retrospectivos , Factores de Riesgo , Estaciones del Año , Vigilancia de Guardia , Adulto JovenRESUMEN
Interim results from Canada's Sentinel Practitioner Surveillance Network show that during a season characterised by early co-circulation of influenza A and B viruses, the 2019/20 influenza vaccine has provided substantial protection against medically-attended influenza illness. Adjusted VE overall was 58% (95% confidence interval (CI): 47 to 66): 44% (95% CI: 26 to 58) for A(H1N1)pdm09, 62% (95% CI: 37 to 77) for A(H3N2) and 69% (95% CI: 57 to 77) for influenza B viruses, predominantly B/Victoria lineage.
Asunto(s)
Subtipo H1N1 del Virus de la Influenza A/aislamiento & purificación , Subtipo H3N2 del Virus de la Influenza A/aislamiento & purificación , Virus de la Influenza B/aislamiento & purificación , Vacunas contra la Influenza/administración & dosificación , Gripe Humana/epidemiología , Gripe Humana/prevención & control , Adolescente , Adulto , Anciano , Antígenos Virales/análisis , Canadá/epidemiología , Niño , Preescolar , Femenino , Genotipo , Pruebas de Inhibición de Hemaglutinación , Humanos , Lactante , Subtipo H1N1 del Virus de la Influenza A/genética , Subtipo H1N1 del Virus de la Influenza A/inmunología , Subtipo H3N2 del Virus de la Influenza A/genética , Subtipo H3N2 del Virus de la Influenza A/inmunología , Virus de la Influenza B/genética , Virus de la Influenza B/inmunología , Vacunas contra la Influenza/inmunología , Masculino , Persona de Mediana Edad , Datos de Secuencia Molecular , Nasofaringe/virología , Nariz/virología , Reacción en Cadena en Tiempo Real de la Polimerasa , Estaciones del Año , Vigilancia de Guardia , Análisis de Secuencia de ADN , Adulto JovenRESUMEN
Vaccine effectiveness (VE) against influenza B was derived separately for Victoria and Yamagata lineages across 8 seasons (2010-2011 to 2017-2018) in Canada when trivalent influenza vaccine was predominantly used. VE was ≥50% regardless of lineage match to circulating viruses, except when the vaccine strain was unchanged from the prior season.
Asunto(s)
Protección Cruzada/inmunología , Virus de la Influenza B/clasificación , Vacunas contra la Influenza/inmunología , Gripe Humana/prevención & control , Estaciones del Año , Potencia de la Vacuna , Adolescente , Adulto , Anciano , Canadá , Niño , Preescolar , Bases de Datos Factuales , Monitoreo Epidemiológico , Femenino , Humanos , Inmunogenicidad Vacunal , Lactante , Vacunas contra la Influenza/normas , Masculino , Persona de Mediana Edad , Adulto JovenRESUMEN
IntroductionFindings from the community-based Canadian Sentinel Practitioner Surveillance Network (SPSN) suggest children were more affected by the 2018/19 influenza A(H1N1)pdm09 epidemic.AimTo compare the age distribution of A(H1N1)pdm09 cases in 2018/19 to prior seasonal influenza epidemics in Canada.MethodsThe age distribution of unvaccinated influenza A(H1N1)pdm09 cases and test-negative controls were compared across A(H1N1)pdm09-dominant epidemics in 2018/19, 2015/16 and 2013/14 and with the general population of SPSN provinces. Similar comparisons were undertaken for influenza A(H3N2)-dominant epidemics.ResultsIn 2018/19, more influenza A(H1N1)pdm09 cases were under 10 years old than controls (29% vs 16%; p < 0.001). In particular, children aged 5-9 years comprised 14% of cases, greater than their contribution to controls (4%) or the general population (5%) and at least twice their contribution in 2015/16 (7%; p < 0.001) or 2013/14 (5%; p < 0.001). Conversely, children aged 10-19 years (11% of the population) were under-represented among A(H1N1)pdm09 cases versus controls in 2018/19 (7% vs 12%; p < 0.001), 2015/16 (7% vs 13%; p < 0.001) and 2013/14 (9% vs 12%; p = 0.12).ConclusionChildren under 10 years old contributed more to outpatient A(H1N1)pdm09 medical visits in 2018/19 than prior seasonal epidemics in Canada. In 2018/19, all children under 10 years old were born after the 2009 A(H1N1)pdm09 pandemic and therefore lacked pandemic-induced immunity. In addition, more than half those born after 2009 now attend school (i.e. 5-9-year-olds), a socio-behavioural context that may enhance transmission and did not apply during prior A(H1N1)pdm09 epidemics.
Asunto(s)
Subtipo H1N1 del Virus de la Influenza A/aislamiento & purificación , Gripe Humana/epidemiología , Gripe Humana/virología , Adolescente , Adulto , Distribución por Edad , Anciano , Canadá/epidemiología , Niño , Preescolar , Efecto de Cohortes , Epidemias , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estaciones del Año , Vigilancia de Guardia , Adulto JovenRESUMEN
Using a test-negative design, the Canadian Sentinel Practitioner Surveillance Network assessed interim 2018/19 vaccine effectiveness (VE) against predominant influenza A(H1N1)pdm09 viruses. Adjusted VE was 72% (95% confidence interval: 60 to 81) against medically attended, laboratory-confirmed influenza A(H1N1)pdm09 illness. This substantial vaccine protection was observed in all age groups, notably young children who appeared to be disproportionately affected. Sequence analysis identified heterogeneity in emerging clade 6B.1 viruses but no dominant drift variant.
Asunto(s)
Subtipo H1N1 del Virus de la Influenza A/aislamiento & purificación , Vacunas contra la Influenza/administración & dosificación , Gripe Humana/prevención & control , Vacunación/estadística & datos numéricos , Potencia de la Vacuna , Adolescente , Adulto , Anciano , Canadá/epidemiología , Estudios de Casos y Controles , Niño , Preescolar , Femenino , Pruebas de Inhibición de Hemaglutinación , Humanos , Lactante , Subtipo H1N1 del Virus de la Influenza A/genética , Subtipo H1N1 del Virus de la Influenza A/inmunología , Vacunas contra la Influenza/inmunología , Gripe Humana/epidemiología , Gripe Humana/virología , Masculino , Persona de Mediana Edad , Nasofaringe/virología , Nariz/virología , Evaluación de Resultado en la Atención de Salud , Reacción en Cadena en Tiempo Real de la Polimerasa , Estaciones del Año , Sensibilidad y Especificidad , Vigilancia de Guardia , Análisis de Secuencia de ADNRESUMEN
IntroductionThe Canadian Sentinel Practitioner Surveillance Network reports vaccine effectiveness (VE) for the 2018/19 influenza A(H3N2) epidemic.AimTo explain a paradoxical signal of increased clade 3C.3a risk among 35-54-year-old vaccinees, we hypothesise childhood immunological imprinting and a cohort effect following the 1968 influenza A(H3N2) pandemic.MethodsWe assessed VE by test-negative design for influenza A(H3N2) overall and for co-circulating clades 3C.2a1b and 3C.3a. VE variation by age in 2018/19 was compared with amino acid variation in the haemagglutinin glycoprotein by year since 1968.ResultsInfluenza A(H3N2) VE was 17% (95% CI: -13 to 39) overall: 27% (95% CI: -7 to 50) for 3C.2a1b and -32% (95% CI: -119 to 21) for 3C.3a. Among 20-64-year-olds, VE was -7% (95% CI: -56 to 26): 6% (95% CI: -49 to 41) for 3C.2a1b and -96% (95% CI: -277 to -2) for 3C.3a. Clade 3C.3a VE showed a pronounced negative dip among 35-54-year-olds in whom the odds of medically attended illness were > 4-fold increased for vaccinated vs unvaccinated participants (p < 0.005). This age group was primed in childhood to influenza A(H3N2) viruses that for two decades following the 1968 pandemic bore a serine at haemagglutinin position 159, in common with contemporary 3C.3a viruses but mismatched to 3C.2a vaccine strains instead bearing tyrosine.DiscussionImprinting by the first childhood influenza infection is known to confer long-lasting immunity focused toward priming epitopes. Our findings suggest vaccine mismatch may negatively interact with imprinted immunity. The immunological mechanisms for imprint-regulated effect of vaccine (I-REV) warrant investigation.
Asunto(s)
Memoria Inmunológica , Subtipo H3N2 del Virus de la Influenza A/aislamiento & purificación , Vacunas contra la Influenza/administración & dosificación , Gripe Humana/prevención & control , Vigilancia de la Población/métodos , Vacunación/estadística & datos numéricos , Potencia de la Vacuna , Adulto , Factores de Edad , Canadá/epidemiología , Femenino , Glicoproteínas Hemaglutininas del Virus de la Influenza/genética , Humanos , Subtipo H3N2 del Virus de la Influenza A/genética , Subtipo H3N2 del Virus de la Influenza A/inmunología , Vacunas contra la Influenza/inmunología , Gripe Humana/epidemiología , Gripe Humana/inmunología , Gripe Humana/virología , Masculino , Persona de Mediana Edad , Vigilancia de GuardiaRESUMEN
An increase in hospital admissions for influenza occurred during the summer of 2015 at an acute care facility in Vancouver, British Columbia, Canada. Investigation identified 25 patients with recent history of cruise ship travel to Alaska. All characterized influenza A viruses were A(H3N2). We describe patient treatment regimens and outcomes.
Asunto(s)
Betainfluenzavirus , Virus de la Influenza A , Gripe Humana/epidemiología , Enfermedad Relacionada con los Viajes , Viaje , Anciano , Anciano de 80 o más Años , Alaska/epidemiología , Colombia Británica/epidemiología , Femenino , Historia del Siglo XXI , Humanos , Virus de la Influenza A/genética , Gripe Humana/historia , Gripe Humana/transmisión , Gripe Humana/virología , Betainfluenzavirus/genética , Masculino , Persona de Mediana EdadRESUMEN
Background: Vaccine effectiveness (VE) estimates for 2015-2016 seasonal influenza vaccine are reported from Canada's Sentinel Practitioner Surveillance Network (SPSN). This season was characterized by a delayed 2009 pandemic influenza A(H1N1) virus (A[H1N1]pdm09) epidemic and concurrent influenza B(Victoria) virus activity. Potential influences on VE beyond antigenic match are explored, including viral genomic variation, birth cohort effects, prior vaccination, and epidemic period. Methods: VE was estimated by a test-negative design comparing the adjusted odds ratio for influenza test positivity among vaccinated compared to unvaccinated participants. Vaccine-virus relatedness was assessed by gene sequencing and hemagglutination inhibition assay. Results: Analyses included 596 influenza A(H1N1)pdm09 and 305 B(Victoria) cases and 926 test-negative controls. A(H1N1)pdm09 viruses were considered antigenically related to vaccine (unchanged since 2009), despite phylogenetic clustering within emerging clade 6B.1. The adjusted VE against A(H1N1)pdm09 was 43% (95% confidence interval [CI], 25%-57%). Compared to other age groups, VE against A(H1N1)pdm09 was lower for adults born during 1957-1976 (25%; 95% CI, -16%-51%). The VE against A(H1N1)pdm09 was also lower for participants consecutively vaccinated during both the current and prior seasons (41%; 95% CI, 18%-57%) than for those vaccinated during the current season only (75%; 95% CI, 45%-88%), and the VE among participants presenting in March-April 2016 (19%; 95% CI, -15%-44%) was lower than that among those presenting during January-February 2016 (62%; 95% CI, 44%-74%). The adjusted VE for B(Victoria) viruses was 54% (95% CI, 32%-68%), despite lineage-level mismatch to B(Yamagata) vaccine. The further variation in VE as observed for A(H1N1)pdm09 was not observed for B(Victoria). Conclusions: Influenza VE findings may require consideration of other agent-host and immuno-epidemiologic influences on vaccine performance beyond antigenic match, including viral genomic variation, repeat vaccination, birth (immunological) cohort effects, and potential within-season waning of vaccine protection.
Asunto(s)
Antígenos Virales/inmunología , Subtipo H1N1 del Virus de la Influenza A/aislamiento & purificación , Virus de la Influenza B/aislamiento & purificación , Vacunas contra la Influenza/administración & dosificación , Vacunas contra la Influenza/inmunología , Gripe Humana/epidemiología , Gripe Humana/prevención & control , Adulto , Factores de Edad , Anciano , Anciano de 80 o más Años , Variación Antigénica , Canadá/epidemiología , Niño , Preescolar , Análisis por Conglomerados , Femenino , Pruebas de Inhibición de Hemaglutinación , Humanos , Inmunización/métodos , Inmunogenicidad Vacunal , Lactante , Subtipo H1N1 del Virus de la Influenza A/clasificación , Subtipo H1N1 del Virus de la Influenza A/genética , Subtipo H1N1 del Virus de la Influenza A/inmunología , Virus de la Influenza B/clasificación , Virus de la Influenza B/genética , Virus de la Influenza B/inmunología , Gripe Humana/virología , Masculino , Persona de Mediana Edad , Filogenia , Análisis de Secuencia de ADN , Homología de Secuencia , Resultado del Tratamiento , Adulto JovenRESUMEN
Background: The antigenic distance hypothesis (ADH) predicts that negative interference from prior season's influenza vaccine (v1) on the current season's vaccine (v2) protection may occur when the antigenic distance is small between v1 and v2 (v1 ≈ v2) but large between v1 and the current epidemic (e) strain (v1 ≠ e). Methods: Vaccine effectiveness (VE) against medically attended, laboratory-confirmed influenza A(H3N2) illness was estimated by test-negative design during 3 A(H3N2) epidemics (2010-2011, 2012-2013, 2014-2015) in Canada. Vaccine effectiveness was derived with covariate adjustment across v2 and/or v1 categories relative to no vaccine receipt among outpatients aged ≥9 years. Prior vaccination effects were interpreted within the ADH framework. Results: Prior vaccination effects varied significantly by season, consistent with the ADH. There was no interference by v1 in 2010-2011 when v1 ≠ v2 and v1 ≠ e, with comparable VE for v2 alone or v2 + v1: 34% (95% confidence interval [CI] = -51% to 71%) versus 34% (95% CI = -5% to 58%). Negative interference by v1 was suggested in 2012-2013 with nonsignificant reduction in VE when v1 ≈ v2 and v1 ≠ e: 49% (95% CI = -47% to 83%) versus 28% (95% CI = -12% to 54%). Negative effects of prior vaccination were pronounced and statistically significant in 2014-2015 when v1 ≡ v2 and v1 ≠ e: 65% (95% CI = 25% to 83%) versus -33% (95% CI = -78% to 1%). Conclusions: Effects of repeat influenza vaccination were consistent with the ADH and may have contributed to findings of low VE across recent A(H3N2) epidemics since 2010 in Canada.
Asunto(s)
Epidemias/prevención & control , Subtipo H3N2 del Virus de la Influenza A , Vacunas contra la Influenza/uso terapéutico , Gripe Humana/prevención & control , Vacunación/estadística & datos numéricos , Adolescente , Adulto , Anciano , Canadá/epidemiología , Estudios de Casos y Controles , Niño , Femenino , Pruebas de Inhibición de Hemaglutinación , Humanos , Vacunas contra la Influenza/inmunología , Gripe Humana/epidemiología , Modelos Logísticos , Masculino , Persona de Mediana Edad , Estaciones del Año , Vigilancia de Guardia , Adulto JovenRESUMEN
Age-related differences in influenza B lineage detection were explored in the community-based Canadian Sentinel Practitioner Surveillance Network (SPSN) from 2010-2011 to 2015-2016. Whereas >80% of B(Victoria) cases were <40 years old, B(Yamagata) cases showed a bimodal age distribution with 27% who were <20 years old and 61% who were 30-64 years old, but with a notable gap in cases between 20 and 29 years old (4%). Overall, the median age was 20 years lower for B(Victoria) vs B(Yamagata) cases (20 vs 40 years; P < .01). Additional phylodynamic and immuno-epidemiological research is needed to understand age-related variation in influenza B risk by lineage, with potential implications for prevention and control across the lifespan.
Asunto(s)
Factores de Edad , Virus de la Influenza B/aislamiento & purificación , Gripe Humana/epidemiología , Vigilancia de Guardia , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Canadá/epidemiología , Estudios de Casos y Controles , Niño , Preescolar , Humanos , Lactante , Recién Nacido , Gripe Humana/diagnóstico , Persona de Mediana Edad , Adulto JovenRESUMEN
Using a test-negative design, the Canadian Sentinel Practitioner Surveillance Network (SPSN) assessed interim 2016/17 influenza vaccine effectiveness (VE) against dominant influenza A(H3N2) viruses considered antigenically matched to the clade 3C.2a vaccine strain. Sequence analysis revealed substantial heterogeneity in emerging 3C.2a1 variants by province and over time. Adjusted VE was 42% (95% confidence interval: 18-59%) overall, with variation by province. Interim virological and VE findings reported here warrant further investigation to inform potential vaccine reformulation.
Asunto(s)
Subtipo H3N2 del Virus de la Influenza A/genética , Subtipo H3N2 del Virus de la Influenza A/aislamiento & purificación , Vacunas contra la Influenza/administración & dosificación , Gripe Humana/prevención & control , Potencia de la Vacuna , Adolescente , Adulto , Anciano , Canadá/epidemiología , Estudios de Casos y Controles , Niño , Preescolar , Femenino , Pruebas de Inhibición de Hemaglutinación , Humanos , Lactante , Subtipo H3N2 del Virus de la Influenza A/inmunología , Vacunas contra la Influenza/inmunología , Gripe Humana/diagnóstico , Gripe Humana/epidemiología , Gripe Humana/virología , Persona de Mediana Edad , Evaluación de Resultado en la Atención de Salud , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Estaciones del Año , Vigilancia de Guardia , Análisis de Secuencia de ADN , Vacunación/estadística & datos numéricos , Adulto JovenRESUMEN
BACKGROUND: The 2014-2015 influenza season was distinguished by an epidemic of antigenically-drifted A(H3N2) viruses and vaccine components identical to 2013-2014. We report 2014-2015 vaccine effectiveness (VE) from Canada and explore contributing agent-host factors. METHODS: VE against laboratory-confirmed influenza was derived using a test-negative design among outpatients with influenza-like illness. Sequencing identified amino acid mutations at key antigenic sites of the viral hemagglutinin protein. RESULTS: Overall, 815/1930 (42%) patients tested influenza-positive: 590 (72%) influenza A and 226 (28%) influenza B. Most influenza A viruses with known subtype were A(H3N2) (570/577; 99%); 409/460 (89%) sequenced viruses belonged to genetic clade 3C.2a and 39/460 (8%) to clade 3C.3b. Dominant clade 3C.2a viruses bore the pivotal mutations F159Y (a cluster-transition position) and K160T (a predicted gain of glycosylation) compared to the mismatched clade 3C.1 vaccine. VE against A(H3N2) was -17% (95% confidence interval [CI], -50% to 9%) overall with clade-specific VE of -13% (95% CI, -51% to 15%) for clade 3C.2a but 52% (95% CI, -17% to 80%) for clade 3C.3b. VE against A(H3N2) was 53% (95% CI, 10% to 75%) for patients vaccinated in 2014-2015 only, significantly lower at -32% (95% CI, -75% to 0%) if also vaccinated in 2013-2014 and -54% (95% CI, -108% to -14%) if vaccinated each year since 2012-2013. VE against clade-mismatched B(Yamagata) viruses was 42% (95% CI, 10% to 62%) with less-pronounced reduction from prior vaccination compared to A(H3N2). CONCLUSIONS: Variation in the viral genome and negative effects of serial vaccination likely contributed to poor influenza vaccine performance in 2014-2015.
Asunto(s)
Genoma Viral/genética , Virus de la Influenza A , Virus de la Influenza B , Vacunas contra la Influenza/inmunología , Gripe Humana , Adolescente , Adulto , Anciano , Canadá/epidemiología , Niño , Preescolar , Femenino , Humanos , Lactante , Virus de la Influenza A/genética , Virus de la Influenza A/inmunología , Virus de la Influenza B/genética , Virus de la Influenza B/inmunología , Gripe Humana/epidemiología , Gripe Humana/inmunología , Gripe Humana/prevención & control , Gripe Humana/virología , Masculino , Persona de Mediana Edad , Vigilancia de Guardia , Adulto JovenRESUMEN
Using a test-negative design, the Canadian Sentinel Practitioner Surveillance Network (SPSN) assessed interim 2015/16 vaccine effectiveness (VE) against influenza A(H1N1)pdm09 viruses. Adjusted VE showed significant protection of 64% (95% confidence interval (CI): 44-77%) overall and 56% (95%CI: 26-73%) for adults between 20 and 64 years-old against medically attended, laboratory-confirmed A(H1N1)pdm09 illness. Among the 67 A(H1N1)pdm09-positive specimens that were successfully sequenced, 62 (> 90%) belonged to the emerging genetic 6B.1 subclade, defined by S162N (potential gain of glycosylation) and I216T mutations in the haemagglutinin protein. Findings from the Canadian SPSN indicate that the 2015/16 northern hemisphere vaccine provided significant protection against A(H1N1)pdm09 illness despite genetic evolution in circulating viruses.
Asunto(s)
Subtipo H1N1 del Virus de la Influenza A/genética , Subtipo H1N1 del Virus de la Influenza A/aislamiento & purificación , Vacunas contra la Influenza/administración & dosificación , Gripe Humana/epidemiología , Gripe Humana/prevención & control , Potencia de la Vacuna , Adolescente , Adulto , Anciano , Canadá/epidemiología , Estudios de Casos y Controles , Niño , Preescolar , Femenino , Pruebas de Inhibición de Hemaglutinación , Humanos , Lactante , Subtipo H1N1 del Virus de la Influenza A/inmunología , Vacunas contra la Influenza/inmunología , Gripe Humana/diagnóstico , Gripe Humana/virología , Persona de Mediana Edad , Evaluación de Resultado en la Atención de Salud , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Estaciones del Año , Vigilancia de Guardia , Vacunación/estadística & datos numéricosRESUMEN
As elsewhere, few (< 15%) sentinel influenza A(H3N2) clade 3C.2a viruses that dominated in Canada during the 2014/15 season could be antigenically characterised by haemagglutination inhibition (HI) assay. Clade 3C.2a viruses that could be HI-characterised had acquired genetic mutations during in vitro cell culture isolation that modified the potential glycosylation motif found in original patient specimens and the consensus sequence of circulating viruses at amino acid positions 158-160 of the haemagglutinin protein. Caution is warranted in extrapolating antigenic relatedness based on limited HI findings for clade 3C.2a viruses that continue to circulate globally.