Background Approaches for determining whether influenza vaccination prevents infection, attenuates illness, or both, are important for developing improved vaccines. We estimated influenza infection incidence, and evaluated symptom ascertainment methodologies in children to inform future vaccine trial design. Methods We conducted a prospective cohort study among children aged 6-23 months from May-October 2022. Study nurses collected symptom and temperature data and mid-turbinate nasal swabs twice-weekly irrespective of symptoms; caregivers entered symptom data daily and collected nasal swabs weekly. Samples were tested for influenza using PCR. Results Of 230 healthy, screened children, 93 were enrolled of whom 87 (94%) completed 6-months follow-up. 95% (4245/4476) of scheduled nurse, 90% (2045/2276) of caregiver swabs, 99% (92/93) of baseline blood collections and 67% (9245/13768) of scheduled symptom diaries were completed. PCR-confirmed influenza incidence was 65% (60/93) for ≥1 infection; 11 (18%) individuals had 2 and 1 (2%) had 3 episodes. Of 73 episodes, 55 (75%) had ≥1 symptom and 37 (51%) had fever (measured and/or reported). Median infection duration was 7 days (interquartile range 4-9). Human RNase P gene was detected in 99% (2032/2045) of caregiver-collected swabs, through which 5 additional episodes were identified. Per episode, caregiver’s diaries of reported and measured fever were 19%(25/73,34%) and 11%(15/73,21%) higher than nurse-reported (11/73,15%) and -measured fevers (7/73,10%), respectively. Conclusions The incidence of influenza infection was high and mainly symptomatic suggesting that this platform could be suitable for future trials of vaccine efficacy and correlates of protection against infection and illness in children.

中文翻译：

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未来疫苗试验的潜在平台确定了南非 6-23 个月儿童有症状和无症状流感感染的高发病率


背景 确定流感疫苗接种是否预防感染、减轻疾病或两者兼而有之的方法对于开发改进的疫苗很重要。我们估计了流感感染的发生率，并评估了儿童的症状确定方法，以指导未来的疫苗试验设计。方法 我们在 2022 年 5 月至 10 月对 6-23 个月大的儿童进行了一项前瞻性队列研究。研究护士每周收集两次症状和体温数据以及中鼻甲鼻拭子，无论症状如何;护理人员每天输入症状数据，并每周收集鼻拭子。使用 PCR 对样本进行流感检测。结果 在 230 例健康、筛查的儿童中，93 例入组，其中 87 例 （94%） 完成了 6 个月的随访。95% （4245/4476） 的预定护士、90% （2045/2276） 的护理人员拭子、99% （92/93） 的基线采血和 67% （9245/13768） 的预定症状日记已完成。PCR 证实的 ≥1 感染流感发病率为 65% （60/93）;11 例 （18%） 个体有 2 次发作，1 例 （2%） 有 3 次发作。在 73 次发作中，55 例 （75%） 有 ≥1 症状，37 例 （51%） 有发热 （测量和/或报告）。中位感染持续时间为 7 天 （四分位距 4-9）。在 99% （2032/2045） 的护理人员收集的拭子中检测到人 RNase P 基因，通过这些拭子确定了另外 5 次发作。每次发作，护理人员报告和测量的发烧日记分别比护士报告的 （11/73,15%） 和 11%（7/73,10%） 高 11%（7/73,15%）和测量的发烧 （7/73,10%）。结论 流感感染的发生率高，以症状为主，提示该平台可能适用于未来疫苗疗效和儿童感染和疾病保护相关性的试验。