Background Previous estimates of vaccine effectiveness (VE) against asymptomatic influenza virus infection based on seroconversion have varied widely and may be biased. We estimated 2022–2023 influenza VE against illness and asymptomatic infection in a prospective cohort. Methods In the HEROES-RECOVER cohort, adults at increased occupational risk of influenza exposure across 7 US sites provided weekly symptom reports and nasal swabs for reverse transcription–polymerase chain reaction (RT-PCR) influenza testing. Laboratory-confirmed influenza virus infections were classified as symptomatic (≥1 symptom) or asymptomatic during the week of testing. Participants reported demographic information and vaccination through surveys; most sites verified vaccination through medical record and immunization registry review. Person-time was calculated as days from the site-specific influenza season start (September–October 2022) through date of infection, study withdrawal, or season end (May 2023). We compared influenza incidence among vaccinated versus unvaccinated participants overall, by symptom status, and by influenza A subtype, using Cox proportional hazards regression adjusted for site and occupation. We estimated VE as (1 − adjusted hazard ratio) × 100%. Results In total, 269 of 3785 (7.1%) participants had laboratory-confirmed influenza, including 263 (98%) influenza A virus infections and 201 (75%) symptomatic illnesses. Incidence of laboratory-confirmed influenza illness among vaccinated versus unvaccinated participants was 23.7 and 33.2 episodes per 100 000 person-days, respectively (VE: 38%; 95% CI: 15%–55%). Incidence of asymptomatic influenza virus infection was 8.0 versus 11.6 per 100 000 (VE: 13%; 95% CI: −47%, 49%). Conclusions Vaccination reduced incidence of symptomatic but not asymptomatic influenza virus infection, suggesting that influenza vaccination attenuates progression from infection to illness.

中文翻译：

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2022-2023 年流感疫苗对疾病和无症状感染的有效性：一项前瞻性队列研究


背景 以前基于血清转换的疫苗对无症状流感病毒感染的有效性 （VE） 的估计差异很大，并且可能存在偏差。我们估计了 2022-2023 年流感 VE 对前瞻性队列中疾病和无症状感染的影响。方法 在 HEROES-RECOVER 队列中，美国 7 个地点的流感暴露职业风险增加的成年人每周提供症状报告和鼻拭子，用于逆转录-聚合酶链反应 （RT-PCR） 流感检测。在检测周内，实验室确诊的流感病毒感染分为有症状 （≥1 症状） 或无症状。参与者通过调查报告了人口统计信息和疫苗接种情况;大多数网站通过病历和免疫登记审查来验证疫苗接种。人用时间计算为从特定部位流感季节开始（2022 年 9 月至 10 月）到感染、研究退出或季节结束（2023 年 5 月）的天数。我们使用针对地点和职业调整的 Cox 比例风险回归，按症状状态和甲型流感亚型比较了接种疫苗和未接种疫苗参与者的总体流感发病率。我们估计 VE 为 （1 − 调整后的风险比） × 100%。结果 3785 名参与者中有 269 名 （7.1%） 患有实验室确诊的流感，包括 263 名 （98%） 甲型流感病毒感染和 201 名 （75%） 有症状的疾病。接种疫苗与未接种疫苗的参与者中实验室确诊的流感疾病发病率分别为每 100 000 人天 23.7 次和 33.2 次（VE：38%;95% CI：15%-55%）。无症状流感病毒感染的发生率分别为每 100 000 人 8.0 例和 11.6 例（VE：13%;95% CI：-47%，49%）。 结论 疫苗接种降低了有症状但非无症状流感病毒感染的发生率，表明流感疫苗接种可减缓从感染到疾病的进展。