Working in healthcare is often considered a risk factor for influenza; however, this risk has not been quantified. We aimed to systematically review evidence describing the annual incidence of influenza among healthy adults and healthcare workers (HCWs). We searched OVID MEDLINE (1950 to 2010), EMBASE (1947 to 2010) and reference lists of identified articles. Observational studies or randomized trials reporting full season or annual influenza infection rates for healthy, working age adult subjects and HCWs were included. Influenza infection was defined as a four-fold rise in antibody titer, or positive viral culture or polymerase chain reaction. From 24,707 citations, 29 studies covering 97 influenza seasons with 58,245 study participants were included. Pooled influenza incidence rates (IR) (95% confidence intervals (CI)) per 100 HCWs per season and corresponding incidence rate ratios (IRR) (95% CI) as compared to healthy adults were as follows. All infections: IR 18.7 (95% CI, 15.8 to 22.1), IRR 3.4 (95% CI, 1.2 to 5.7) in unvaccinated HCWs; IR 6.5 (95% CI, 4.6 to 9.1), IRR 5.4 (95% CI, 2.8 to 8.0) in vaccinated HCWs. Symptomatic infections: IR 7.5 (95% CI, 4.9 to 11.7), IRR 1.5 (95% CI, 0.4 to 2.5) in unvaccinated HCWs, IR 4.8 (95% CI, 3.2 to 7.2), IRR 1.6 (95% CI, 0.5 to 2.7) in vaccinated HCWs. Compared to adults working in non-healthcare settings, HCWs are at significantly higher risk of influenza.

Aim: To determine factors associated with a serious outcome (hospital admission or severe outcome: critical care or death) and associated with illness caused by laboratory‐confirmed influenza, with a specific interest in low‐ and middle‐income countries (LMIC).Method: Databases were searched on 11 March 2016 for reports of influenza and factors associated with mortality or morbidity in humans, with no language restrictions. Pooled risks were estimated using random‐effects models.Results: Despite the heterogeneity of results across studies, known risk factors for serious disease were associated with both hospital admission and severe outcomes (critical care and/or death). InLMIC, but not in high income countries (HIC), pregnant women, people withHIV/AIDSand children < 5 years old (compared with older children) were at increased risk of a severe outcome. Also, although all patients with neurological conditions were at higher risk of severe outcomes than those without, children were at higher risk than adults and children who lived in aLMICwere at significantly higher risk than those living inHIC. Adults were more likely than children to suffer a severe outcome if they had diabetes or a hematologic condition, were obese or had liver disease. Asthma is a risk factor for hospital admission but not for severe outcomes.Conclusion: Known risk factors for serious disease remain important predictors of hospital admission and severe outcomes with few differences betweenHICandLMICcountries. These differences likely reflect differences in health‐seeking behaviours and health services, but high heterogeneity between studies limits conclusions about the effect size.

Background: Standard‐dose seasonal influenza vaccines often produce modest immunogenic responses in adults ≥65 years old. MF59 is intended to elicit a greater magnitude and increased breadth of immune response.Objective: To determine the effectiveness of seasonal MF59‐adjuvanted trivalent/quadrivalent influenza vaccine (aTIV/aQIV) relative to no vaccination or vaccination with standard or high‐dose egg‐based influenza vaccines among people ≥65 years old.Methods: Cochrane methodological standards and PRISMA‐P guidelines were followed. Real‐world evidence from non‐interventional studies published in peer‐reviewed journals and gray literature from 1997 through to July 15, 2020, including cluster‐randomized trials, were eligible. Two reviewers independently extracted data; risk of bias was assessed using the ROBINS‐I tool.Results: Twenty‐one studies conducted during the 2006/07–2019/20 influenza seasons were included in the qualitative review; 16 in the meta‐analyses. Meta‐analysis of test‐negative studies found that aTIV reduced medical encounters due to lab‐confirmed influenza with pooled estimates of 40.7% (95% CI: 21.9, 54.9; I² = 0%) for non‐emergency outpatient visits and 58.5% (40.7, 70.9; I² = 52.9%) for hospitalized patients. The pooled estimate of VE from case‐control studies was 51.3% (39.1, 61.1; I² = 0%) against influenza‐ or pneumonia‐related hospitalization. The pooled estimates for the relative VE of aTIV for the prevention of influenza‐related medical encounters were 13.9% (4.2, 23.5; I² = 95.9%) compared with TIV, 13.7% (3.1, 24.2; I² = 98.8%) compared with QIV, and 2.8% (−2.9, 8.5; I² = 94.5%) compared with HD‐TIV.Conclusions: Among adults ≥65 years, aTIV demonstrated significant absolute VE, improved relative VE compared to non‐adjuvanted standard‐dose TIV/QIV, and comparable relative VE to high‐dose TIV.

The gold standard for respiratory virus testing is a nasopharyngeal (NP) swab, which is collected by a healthcare worker. Midturbinate (MT) swabs are an alternative due to their ease of collection and possible self-collection by patients. The objective of this study was to compare the respiratory virus isolation of flocked MT swabs compared to flocked NP swabs. Beginning in October 2008, healthy adults aged 18 to 69 years were recruited into a cohort and followed up for symptoms of influenza. They were asked to have NP and MT swabs taken as soon as possible after the onset of a fever or two or more respiratory symptoms with an acute onset. The swabs were tested for viral respiratory infections using Seeplex® RV12 multiplex PCR detection kit. Seventy six pairs of simultaneous NP and MT swabs were collected from 38 symptomatic subjects. Twenty nine (38%) of these pairs were positive by either NP or MT swabs or both. Sixty nine (91%) of the pair results were concordant. Two samples (3%) for hCV OC43/HKU1 and 1 sample (1%) for rhinovirus A/B were positive by NP but negative by MT. One sample each for hCV 229E/NL63, hCV OC43/HKU1, respiratory syncytial virus A, and influenza B were positive by MT but negative by NP. Flocked MT swabs are sensitive for the diagnosis of multiple respiratory viruses. Given the ease of MT collection and similar results between the two swabs, it is likely that MT swabs should be the preferred method of respiratory cell collection for outpatient studies. In light of this data, larger studies should be performed to ensure that this still holds true and data should also be collected on the patient preference of collection methods.

Background: Fewer Canadian seniors are vaccinated against pneumococcal disease than receive the influenza vaccine annually. Improved understanding of factors influencing pneumococcal vaccination among older adults is needed to improve vaccine uptake. Methods: A self-administered survey measuring knowledge, attitudes, beliefs and behaviours about pneumococcal vaccination was administered to a cohort of seniors participating in a clinical trial of seasonal influenza vaccines at eight centers across Canada. Eligible participants were ambulatory adults 65 years of age or older, in good health or with stable health conditions, previously given influenza vaccine. The primary outcome was self-reported receipt of pneumococcal vaccination. Multi-variable logistic regression was used to determine factors significantly associated with pneumococcal vaccine receipt. Results: A total of 863 participants completed questionnaires (response rate 92%); 58% indicated they had received the pneumococcal vaccine. Being offered the vaccine by a health care provider had the strongest relationship with vaccine receipt (AOR 23.4 (95% CI 13.4-40.7)). Other variables that remained significantly associated with vaccine receipt in the multivariable model included having heard of the vaccine (AOR 10.1(95% CI 4.7-21.7)), and strongly agreeing that it is important for adults > 65 to be vaccinated against pneumococcus (AOR 3.3 (95% CI 1.2-9.2)). Participants who were < 70 years of age were less likely to be vaccinated. Conclusions: These results indicate healthcare recommendation significantly influenced vaccine uptake in this population of older adults. Measures to encourage healthcare providers to offer the vaccine may help increase coverage.