RESUMEN
BackgroundWaning immunity from seasonal influenza vaccination can cause suboptimal protection during peak influenza activity. However, vaccine effectiveness studies assessing waning immunity using vaccinated and unvaccinated individuals are subject to biases.AimWe examined the association between time since vaccination and laboratory-confirmed influenza to assess the change in influenza vaccine protection over time.MethodsUsing linked laboratory and health administrative databases in Ontario, Canada, we identified community-dwelling individuals aged ≥ 6 months who received an influenza vaccine before being tested for influenza by RT-PCR during the 2010/11 to 2018/19 influenza seasons. We estimated the adjusted odds ratio (aOR) for laboratory-confirmed influenza by time since vaccination (categorised into intervals) and for every 28 days.ResultsThere were 53,065 individuals who were vaccinated before testing for influenza, with 10,264 (19%) influenza-positive cases. The odds of influenza increased from 1.05 (95%â¯CI: 0.91-1.22) at 42-69 days after vaccination and peaked at 1.27 (95%â¯CI: 1.04-1.55) at 126-153 days when compared with the reference interval (14-41 days). This corresponded to 1.09-times increased odds of influenza every 28 days (aOR = 1.09; 95%â¯CI: 1.04-1.15). Individuals aged 18-64 years showed the greatest decline in protection against influenza A(H1N1) (aORperâ¯28â¯days = 1.26; 95%â¯CI: 0.97-1.64), whereas for individuals aged ≥ 65 years, it was against influenza A(H3N2) (aORperâ¯28â¯days = 1.20; 95%â¯CI: 1.08-1.33). We did not observe evidence of waning vaccine protection for individuals aged < 18 years.ConclusionsInfluenza vaccine protection wanes during an influenza season. Understanding the optimal timing of vaccination could ensure robust protection during seasonal influenza activity.
Asunto(s)
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 , Ontario/epidemiología , Subtipo H3N2 del Virus de la Influenza A , VacunaciónRESUMEN
Background: Delays in COVID-19 testing may increase the risk of secondary household and community transmission. Little is known about what patient characteristics and symptom profiles are associated with delays in test seeking. Methods: We conducted a retrospective cohort study of all symptomatic patients diagnosed with COVID-19 and assessed in a COVID Expansion to Outpatients (COVIDEO) virtual care program between March 2020 and June 2021. The primary outcome was later test seeking more than 3 days from symptom onset. Multivariable logistic regression was used to examine predictors of later testing including patient characteristics and symptoms (30 individual symptoms or 7 symptom clusters). Results: Of 5,363 COVIDEO patients, 4,607 were eligible and 2,155/4,607 (46.8%) underwent later testing. Older age was associated with increased odds of late testing (adjusted odds ratio [aOR] 1.007/year; 95% CI 1.00 to 1.01), as was history of recent travel (aOR 1.4; 95% CI 1.01 to 1.95). Health care workers had lower odds of late testing (aOR 0.50; 95% CI 0.39 to 0.62). Late testing was associated with symptoms in the cardiorespiratory (aOR 1.2; 95% CI 1.05, 1.36), gastrointestinal (aOR = 1.2; 95% CI 1.04, 1.4), neurological (aOR 1.1; 95% CI 1.003, 1.3) and psychiatric (aOR 1.3; 95% CI 1.1, 1.5) symptom clusters. Among individual symptoms, dyspnea, anosmia, dysgeusia, sputum, and anorexia were associated with late testing; pharyngitis, myalgia, and headache were associated with early testing. Conclusion: Certain patient characteristics and symptoms are associated with later testing, and warrant further efforts to encourage earlier testing to minimize transmission.
Historique: Les retards à effectuer les tests de dépistage de la COVID-19 peuvent accroître le risque de transmission secondaire dans la famille et la communauté. On ne sait pas vraiment quels sont les caractéristiques des patients et leurs profils de symptômes associés aux retards à se faire dépister. Méthodologie: Les chercheurs ont réalisé une étude de cohorte auprès de tous les patients symptomatiques ayant obtenu un diagnostic de COVID-19 évalués dans le cadre du programme de soins virtuels COVID Expansion to Outpatients (COVIDEO, ou expansion de la COVID aux patients ambulatoires) entre mars 2020 et juin 2021. Le résultat primaire était une demande de dépistage plus de trois jours après l'apparition des symptômes. Les chercheurs ont utilisé la régression logistique multivariable pour examiner les prédicteurs d'un dépistage tardif, y compris les caractéristiques et les symptômes des patients (30 symptômes individuels ou sept grappes de symptômes). Résultats: Des 5 363 patients ayant participé au programme COVIDEO, 4 607 étaient admissibles et 2 155 de ces 4 607 (46,8 %) se sont soumis à un dépistage tardif. Une plus grande probabilité de dépistage tardif était liée à un âge avancé (rapport de cotes corrigé [RCc] 1,007/année, IC à 95 %, 1,00 à 1,01), de même qu'à un voyage récent (RCc = 1,4, IC à 95 %, 1,01 à 1,95). Les travailleurs de la santé étaient moins susceptibles de se faire dépister tardivement (RCc = 0,50, IC à 95 %, 0,39 à 0,62). Le dépistage tardif était associé à des symptômes de la grappe cardiorespiratoire (RCc = 1,2, IC à 95 %, [1,05, 1,36]), gastrointestinale (RCc = 1,2, IC à 95 %, [1,04, 1,4]), neurologique (RCc = 1,1, IC à 95 %, [1,003, 1,3]) et psychiatrique (RCc = 1,3, IC à 95 %, [1,1, 1,5]). Parmi les symptômes individuels, la dyspnée, l'anosmie, la dysgueusie, les expectorations et l'anorexie étaient associées à un dépistage tardif, et la pharyngite, les myalgies et les céphalées, à un dépistage précoce. Conclusion: Certaines caractéristiques des patients et certains symptômes étaient associés à un dépistage tardif, ce qui justifie des efforts supplémentaires pour favoriser un dépistage plus rapide afin de limiter la transmission. Summary: This study of more than 4,000 patients with COVID-19 identified predictors of later test seeking, including older age, recent travel, non-health care worker occupation, cardiorespiratory, gastrointestinal, neurologic and psychiatric symptom clusters, and dyspnea, anosmia, dysgeusia, sputum, and anorexia.