Incidence Of Influenza Research Articles

Evaluation of the preventive effectiveness of russian influenza vaccines in the epidemic seasons of 2018-2021

Monitoring the effectiveness of influenza vaccines annually enables the development of measures aimed at decreasing influenza incidence, hospitalization, and mortality rates. The epidemiological effectiveness of several Russian domestic influenza vaccines was evaluated in St. Petersburg in the 2018-2021 epidemic seasons. Male and female participants (N = 6912) aged 18-23 were monitored from 2018 to 2021. Sovigripp, Grippol Plus, Ultrix, and Ultrix Quadri inactivated influenza vaccines were used for immunization. In 2018-2019, when the vaccine strains fully matched the circulating influenza viruses, prophylactic vaccination resulted in a 2.7 to 7.1-fold reduction in influenza cases. The protective effectiveness of the vaccines against influenza and acute respiratory infections (ARIs) totalled 52.4%, reaching 73.0% effectiveness against influenza after laboratory confirmation. In the epidemic season 2019-2020, when the circulating viruses and vaccine strains did not fully match, the incidence of influenza and ARIs reduced twice due to vaccination; the total vaccine effectiveness against influenza and ARIs amounted to 50.0%. The Grippol Plus, Ultrix, and Ultrix Quadri vaccines proved to be the most effective, demonstrating a total effectiveness of 70.6%-75.0% and a 65.5%-83.5% effectiveness against influenza A and B. In the 2020-2021 epidemic season, no data on the preventive effectiveness of the influenza vaccines could be obtained due to the outbreak of COVID-19 and the absence of detectable influenza virus shedding in the study participants. The results obtained are consistent with WHO experts’ estimates which indicate that modern influenza vaccines reduce the incidence of influenza in adults by 70-90% if the vaccine strains match the circulating virus strains.

Influenza Vaccine Effectiveness Against Illness and Asymptomatic Infection in 2022-2023: A Prospective Cohort Study.

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. 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%. 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%). Vaccination reduced incidence of symptomatic but not asymptomatic influenza virus infection, suggesting that influenza vaccination attenuates progression from infection to illness.

Epidemiology and population-based incidence of influenza in two communities, Bandung district, West Java, Indonesia, 2008–2011

Influenza surveillance is important for monitoring influenza virus circulation and disease burden to inform influenza prevention and control measures. The aim of this study was to describe the epidemiology and to estimate the incidence of influenza in two communities in West Java, Indonesia, before and after the 2009 H1N1 pandemic. A population-based surveillance study in the community health care setting was conducted to estimate the annual incidence of influenza. A real-time reverse transcription polymerase chain reaction (RT-PCR) assay was used for influenza case ascertainment. A population census was implemented to calculate the population at risk and estimate community health care utilization rate. The mean annual incidence of influenza A and B, adjusted for healthcare utilization, was 1.6 (95%CI: 1.3–2.0) and 0.7 (95%CI: 0.5–1.0) per 1000 persons, respectively, with the most affected group being young and school-age children. The annual cumulative incidence of influenza A for children under five in 2009, 2010, and 2011 was 7.0 (95%CI: 4.4–11.2), 10.6 (95%CI: 7.3–15.4), and 6.3 (95%CI: 3.8–10.2). For influenza B was 4.3 (95%CI: 2.4–7.8), 2.0 (95%CI: 0.8–4.7), and 0.4 (95%CI: 0.1–2.8), respectively. This study highlights that the incidence of influenza among young and school-age children is consistently higher compared to adults and the elderly throughout these periods. These populations are potential targets for influenza vaccination in Indonesia.

Temperature variability and influenza incidence in China: Effect modification by ambient fine particulate matter

This study aims to examine the association between temperature variabilit (TV) exposure and influenza incidence in China, and the modification effect of PM2.5 levels. Data on daily influenza cases, weather conditions, and PM2.5 concentrations were collected from 339 cities across mainland China from 2014 to 2019. TV was computed as the standard deviation of daily maximum and minimum temperatures for the current day and the previous several days (i.e., TV0–1 to TV0–7). A space-time-stratified case-crossover design with conditional Poisson regression was employed. Overall, each 1 °C increase in TV0–6 was linked to 3.3 % (95 % CI: 3.1 %, 3.5 %) rise in influenza incidence, potentially attributing 14.73 % (95 % CI: 14.08 %, 15.37 %) of cases to this exposure. PM2.5 concentration showed substantial modification effect on the association, such that the relative risk (RR) of influenza incidence grew from 1.027 (95 % CI: 1.025, 1.029) to 1.040 (95 % CI: 1.038, 1.042) as PM2.5 levels increased from 15 to 75 μg/m³ . Females and individuals over 65 years old were more susceptible to TV exposure and the PM2.5 modification. Stronger effects were observed during cold season and in North region. The findings highlight the integrating considerations of TV and PM2.5 exposures into public health measures for influenza prevention and control.

Evaluation and control strategy analysis of influenza cases in Jiujiang City, Jiangxi Province, China from 2018 to 2022.

According to World Trade Organization (WTO) statistics, the incidence of seasonal influenza in China has been on the rise since 2018. The aim of this study was to identify and investigate the influence of factors related to the incidence of four common types of influenza viruses. Data of patients with common cold and associated virus infections are described, and a logistic regression model based on gender, age and season was established. The relationship between virus type and the above three factors was analyzed in depth and significant (p<0.05) associations noted. We noted a fluctuation trend, with the infection rate of influenza virus showing an upward trend from 2018 to 2019 and from 2021 to 2022 and a downward trend from 2019 to 2021. The total number of cases in adolescents aged 18-30 years was higher than that in the elderly. The impact of different types of influenza virus on the population ranked from large to small, with special roles played by Influenza B/Victoria, H3N2, Influenza A/H1N1 pdm and Influenza B/Yamagata.

Optimization of timing for maternal immunization to protect newborns from influenza infection

Objectives The primary objective of this systematic review was to identify the optimal timing for immunizing pregnant women to confer the most protection by reducing the incidence of laboratory-confirmed influenza or influenza-like illness in infants less than 6 months of age. Currently, there are gaps in research regarding the timing of administration during the gestational period to provide maximum immunogenicity to the infant. The research question being addressed is: ‘When considering immunization of pregnant mothers with the influenza vaccine, implementing a vaccination program during which trimester in pregnancy would optimize benefits for infants less than 6 months of age in terms of the incidence of laboratory-confirmed influenza and influenza-like illness?’ Design Systematic review/Meta-analysis Methods Randomized controlled trials (RCT’s) and observational studies comparing health outcomes of infants and children up to 6 months of age born to women who received inactivated influenza vaccine during pregnancy with mothers who did not receive the vaccine or received a control vaccine. The primary outcome was laboratory-confirmed influenza infection in infants. Secondary outcome measures included influenza –like illness diagnosed by a clinician and acute respiratory illness. Results 7 studies were included: 2 primary RCT’s and 5 observational studies (prospective and retrospective cohort studies).5 of the 7 studies were suitable to be included in the quantitative synthesis part and and were compared. Forrest plot analysis revealed that vaccinating pregnant mothers in the second and third trimester when compared with any trimester (1,2 and 3) (OR 0.18 vs. 0.65) conferred less protection, promoting vaccination in the first trimester. Conclusions Vaccinating pregnant mothers in the first trimester conferred greater protection to infants than any other trimester.

Effect of calcium channel blockers on influenza incidence: a population-based retrospective cohort study using administrative claims data in Japan

ObjectivesLaboratory experiments have indicated that calcium channel blockers (CCBs) inhibit the entry and replication of influenza A virus in cells. However, no clinical studies have assessed the incidence of influenza...

The added value of serologic testing: a comparison of influenza incidence among pregnant persons based on molecular-based surveillance versus serologic testing

BackgroundWe examined the added value of serologic testing for estimating influenza virus infection incidence based on illness surveillance with molecular testing versus periodic serologic testing. MethodsPregnant persons unvaccinated against influenza at <28 weeks gestation were enrolled before the 2017 and 2018 influenza seasons in Peru and Thailand. Blood specimens were collected at enrollment and ≤14 days postpartum for testing by hemagglutination inhibition assay for antibodies against influenza reference viruses. Seroconversion was defined as a ≥4-fold rise in antibody titers from enrollment to postpartum with the second specimen's titer of ≥40. Throughout pregnancy, participants responded to twice weekly surveillance contacts asking about influenza vaccination and influenza-like symptoms (ILS). A mid-turbinate swab was collected with each ILS episode for influenza real-time reverse transcription PCR (rRT-PCR). ResultsOf 1,466 participants without evidence of influenza vaccination during pregnancy, 296 (20.2%) had evidence of influenza virus infections. Fifteen (5.1%) were detected by rRT-PCR only, 250 (84.4%) by serologic testing only, and 31 (10.5%) by both methods. ConclusionsInfluenza virus infections during pregnancy occurred in 20% of cohort participants; >80% were not detected by a broad illness case definition coupled with rRT-PCR.

Efficacy and feasibility of a novel semi-facial respirator with chitosan nanoparticles on the incidence of SARS-CoV-2 infection in healthcare professionals: randomized controlled trial

BackgroundEvidence suggests that semi-facial respirators provide protection against contamination in high-risk environments, although the COVID-19 pandemic called for greater protection and viral inactivation capacity. Thus, the aim of this study was to investigate the efficacy of a novel semi-facial respirator containing chitosan nanoparticles, compared with a conventional N95 respirator on the incidence of laboratory-confirmed SARS-CoV-2 in healthcare professionals. The secondary outcomes were influenza infection, usability and comfort.MethodsRandomized controlled trial within a large public hospital (reference for COVID-19 patients) carried out between March 2021 and June 2023. We included 230 healthcare professionals exposed to SARS-Cov-2 and influenza, working in emergency departments, hospital wards, and intensive care units. Participants were assessed at baseline, after 10 days, and 21 days of follow-up. Researchers, participants, and outcome assessors were blinded to the allocated groups. Outcomes were analyzed by bivariate and multivariate comparisons using logistic regression. Crude (cOR) and adjusted odds ratios (aOR) were estimated, followed by 95% confidence intervals (CIs 95%). We adopted intention-to-treat (ITT) and complete-case (CC) analyses.ResultsBaseline characteristics were considered homogeneous between groups, and usability and comfort were reported as excellent in both groups. Non-significant differences were found for all outcomes, both in the ITT and CC analyses. The incidence of COVID-19 and influenza were, respectively, cOR: 0.96 [CI95%: 0.21–4.42] and cOR: 1.25 [CI95%: 0.34–4.62]; and aOR: 1.08 [CI95%: 0.21–5.47] and aOR: 1.11 [CI95%: 0.17–7.01].ConclusionsWe found that the incidence of SARS-Cov-2 and influenza infections were similar between the new respirator compared to the conventional respirator. Furthermore, we observed that usability and comfort were similar and considered excellent for both respirators.Trial registrationClinicaltrials.gov (NCT04490200, 29/07/2020).

Characterizing the seasonal influenza disease burden attributable to climate variability: A nationwide time-series modelling study in Japan, 2000−2019

BackgroundAmbient temperature and humidity are established environmental stressors with regard to influenza infections; however, mapping disease burden is difficult owing to the complexities of the underlying associations and differences in vulnerable population distributions. In this study, we aimed to quantify the burden of influenza attributable to non-optimal ambient temperature and absolute humidity in Japan considering geographical differences in vulnerability. MethodsThe exposure−lag−response relationships between influenza incidence, ambient temperature, and absolute humidity in all 47 Japanese prefectures for 2000−2019 were quantified using a distributed lag non-linear model for each prefecture; the estimates from all the prefectures were then pooled using a multivariate mixed-effects meta-regression model to derive nationwide average associations. Association between prefecture-specific indicators and the risk were also examined. Attributable risks were estimated for non-optimal ambient temperature and absolute humidity according to the exposure−lag−response relationships obtained before. ResultsA total of 25,596,525 influenza cases were reported during the study period. Cold and dry conditions significantly increased influenza incidence risk. Compared with the minimum incidence weekly mean ambient temperature (29.8 °C) and the minimum incidence weekly mean absolute humidity (20.2 g/m3), the cumulative relative risks (RRs) of influenza in cold (2.5 °C) and dry (3.6 g/m3) conditions were 2.79 (95% confidence interval [CI]: 1.78−4.37) and 3.20 (95% CI: 2.37−4.31), respectively. The higher RRs for cold and dry conditions were associated with geographical and climatic indicators corresponding to the central and northern prefectures; demographic, socioeconomic, and health resources indicators showed no clear trends. Finally, 27.25% (95% empirical CI [eCI]: 5.54−36.35) and 32.35% (95% eCI: 22.39−37.87) of all cases were attributable to non-optimal ambient temperature and absolute humidity (6,976,300 [95% eCI: 1,420,068−9,306,128] and 8,280,981 [95% eCI: 8,280,981−9,693,532] cases), respectively. ConclusionsThese findings could help identify the most vulnerable populations in Japan and design adaptation policies to reduce the attributable burden of influenza due to climate variability.

Exploring the influence of environmental indicators and forecasting influenza incidence using ARIMAX models.

Influenza is a respiratory infection that poses a significant health burden worldwide. Environmental indicators, such as air pollutants and meteorological factors, play a role in the onset and propagation of influenza. Accurate predictions of influenza incidence and understanding the factors influencing it are crucial for public health interventions. Our study aims to investigate the impact of various environmental indicators on influenza incidence and apply the ARIMAX model to integrate these exogenous variables to enhance the accuracy of influenza incidence predictions. Descriptive statistics and time series analysis were employed to illustrate changes in influenza incidence, air pollutants, and meteorological indicators. Cross correlation function (CCF) was used to evaluate the correlation between environmental indicators and the influenza incidence. We used ARIMA and ARIMAX models to perform predictive analysis of influenza incidence. From January 2014 to September 2023, a total of 21,573 cases of influenza were reported in Fuzhou, with a noticeable year-by-year increase in incidence. The peak of influenza typically occurred around January each year. The results of CCF analysis showed that all 10 environmental indicators had a significant impact on the incidence of influenza. The ARIMAX(0, 0, 1) (1, 0, 0)12 with PM10(lag5) model exhibited the best prediction performance, as indicated by the lowest AIC, AICc, and BIC values, which were 529.740, 530.360, and 542.910, respectively. The model achieved a fitting RMSE of 2.999 and a predicting RMSE of 12.033. This study provides insights into the impact of environmental indicators on influenza incidence in Fuzhou. The ARIMAX(0, 0, 1) (1, 0, 0)12 with PM10(lag5) model could provide a scientific basis for formulating influenza control policies and public health interventions. Timely prediction of influenza incidence is essential for effective epidemic control strategies and minimizing disease transmission risks.

Spatial-temporal evolution patterns of influenza incidence in Xinjiang Prefecture from 2014 to 2023 based on GIS

Using GIS technology, this study investigated the spatiotemporal distribution pattern of influenza incidence in Xinjiang from 2014 to 2023 based on influenza surveillance data. The study revealed a noticeable fluctuation trend in influenza incidence rates in Xinjiang, particularly notable spikes observed in 2019 and 2023. The results of the 3-year moving average showed a significant long-term upward trend in influenza incidence rates, confirmed by Theil-Sen method (MAD = 2.202, p < 0.01). Global spatial autocorrelation analysis indicated significant positive spatial autocorrelation in influenza incidence rates from 2016 and from 2018 to 2023 (Moran’s I > 0, P < 0.05). Local spatial autocorrelation analysis further revealed clustering patterns in different regions, with high-high clustering and low-high clustering predominating in northern Xinjiang, and low-low clustering predominating in southern Xinjiang. Hotspot analysis indicated a progressive rise in the number of influenza incidence hotspots, primarily concentrated in northern Xinjiang, particularly in Urumqi, Ili Kazakh Autonomous Prefecture, and Hotan Prefecture. Standard deviation ellipse analysis and the trajectory of influenza incidence gravity center migration showed that the transmission range of influenza in Xinjiang has been expanding, with the epidemic center gradually moving northward. The spatiotemporal heterogeneity of influenza incidence in Xinjiang highlights the need for differentiated and precise influenza prevention and control strategies in different regions to address the changing trends in influenza prevalence.

Risk of cardiovascular events after influenza infection-related hospitalizations in adults with congenital heart disease: A nationwide population based study

BackgroundCardiovascular complications due to viral infection pose a significant risk in vulnerable patients such as those with congenital heart disease (CHD). Limited data exists regarding the incidence of influenza and its impact on cardiovascular outcomes among this specific patient population. MethodsA retrospective cohort study was designed using the Canadian Congenital Heart Disease (CanCHD) database - a pan-Canadian database of CHD patients with up to 35 years of follow-up. CHD patients aged 40 to 65 years with influenza virus-associated hospitalizations between 2010 and 2017 were identified and 1:1 matched with CHD patients with limb fracture hospitalizations on age and calendar time. Our primary endpoint was cardiovascular complications: heart failure, acute myocardial infarction, atrial arrhythmia, ventricular arrhythmia, heart block, myocarditis, and pericarditis. ResultsOf the 303 patients identified with incident influenza virus-associated hospitalizations, 255 were matched to 255 patients with limb fracture hospitalizations. Patients with influenza virus-related hospitalizations showed significantly higher cumulative probability of cardiovascular complications at one year (0.16 vs. 0.03) and five years (0.33 vs. 0.15) compared to patients hospitalized with bone fracture. Time-dependent hazard function modeling demonstrated a significantly higher risk of cardiovascular complications within nine months post-discharge for influenza-related hospitalizations. This association was confirmed by Cox regression model (average hazard ratio throughout follow-up: 2.48; 95% CI: 1.59 – 3.84). ConclusionsThis pan-Canadian cohort study of adults with CHD demonstrated an association between influenza virus-related hospitalization and risk of cardiovascular complications during the nine months post discharge. This data is essential in planning surveillance strategies to mitigate adverse outcomes and provides insights into interpreting complication rates of other emerging pathogens, such as COVID-19.

Seasonal patterns of influenza incidence and the influence of meteorological and air pollution factors in Thailand during 2009–2019

Influenza, an acute respiratory illness, remains a significant public health challenge, contributing substantially to morbidity and mortality worldwide. Its seasonal prevalence exhibits diversity across regions with distinct climates. This study aimed to explore the seasonal patterns of influenza and their correlation with meteorological and air pollution factors across six regions of Thailand. We conducted an analysis of monthly average temperature, relative humidity, precipitation, PM10, NO2, O3 concentrations, and influenza incidence data from 2009 to 2019 using wavelet analysis. Our findings reveal inconsistent biannual influenza prevalence patterns throughout the study period. The biannual pattern emerged during 2010–2012 across all regions but disappeared during 2013–2016. However, post-2016, the biannual cycles resurfaced, with peaks occurring during the rainy and winter seasons in most regions, except for the southern region. Wavelet coherence reveals that relative humidity can be the main influencing factor for influenza incidence over a one-year period in the northern, northeastern, central, Bangkok-metropolitan, and eastern regions, not in the southern region during 2010–2012 and 2016–2018. Similarly, precipitation can drive the influenza incidence at the same period for the northeastern, central, Bangkok-metropolitan, and eastern regions. PM10 concentration can influence influenza incidence over a half-year period in the northeastern, central, Bangkok-metropolitan, and eastern regions of Thailand during certain years. These results enhance our understanding of the temporal dynamics of influenza seasonality influenced by weather conditions and air pollution over the past 11 years. Such knowledge is invaluable for resource allocation in clinical settings and informing public health strategies, particularly in navigating Thailand's climatic complexities.

Increased Risk of Influenza Infection During Cold Spells in China: National Time Series Study.

Studies have reported the adverse effects of cold events on influenza. However, the role of critical factors, such as characteristics of cold spells, and regional variations remain unresolved. We aimed to systematically evaluate the association between cold spells and influenza incidence in mainland China. This time series analysis used surveillance data of daily influenza from 325 sites in China in the 2014-2019 period. A total of 15 definitions of cold spells were adopted based on combinations of temperature thresholds and days of duration. A distributed lag linear model was used to estimate the short-term effects of cold spells on influenza incidence during the cool seasons (November to March), and we further explored the potential impact of cold spell characteristics (ie, intensity, duration, and timing during the season) on the estimated associations. Meta-regressions were used to evaluate the modification effect of city-level socioeconomic indicators. The overall effect of cold spells on influenza incidence increased with the temperature threshold used to define cold spells, whereas the added effects were generally small and not statistically significant. The relative risk of influenza-associated with cold spells was 3.35 (95% CI 2.89-3.88), and the estimated effects were stronger during the middle period of cool seasons. The health effects of cold spells varied geographically and residents in Jiangnan region were vulnerable groups (relative risk 7.36, 95% CI 5.44-9.95). The overall effects of cold spells were positively correlated with the urban population density, population size, gross domestic product per capita, and urbanization rate, indicating a sterner response to cold spells in metropolises. Cold spells create a substantial health burden on seasonal influenza in China. Findings on regional and socioeconomic differences in the health effects of cold spells on seasonal influenza may be useful in formulating region-specific public health policies to address the hazardous effects of cold spells.

Effectiveness of annual influenza campaigns and vaccination in reducing influenza burden in nursing homes of Canton Vaud in Switzerland

BackgroundInfluenza infections pose significant risks for nursing home (NH) residents. Our aim was to evaluate the impact of the cantonal influenza campaign, and influenza vaccination coverage of residents and healthcare workers (HCWs) on influenza burden in NHs in a context of enhanced infection prevention and control measures (IPC) during the SARS-CoV-2 pandemic.MethodsWe extracted data from epidemic reports provided by our unit to NHs over two consecutive winter seasons (2021-22 and 2022-23) and used linear regression to assess the impact of resident and HCW vaccination coverage, and participation in the campaign, on residents’ cumulative influenza incidence and mortality.ResultsThirty-six NHs reported 155 influenza cases and 21 deaths during the two winter seasons corresponding to 6.2% of infected residents and a case fatality ratio of 13.5%. Median vaccination coverage was 83% for residents, 25.8% for HCWs, while 87% of NHs participated in the campaign. Resident vaccination was significantly associated with a decrease in odds of death (odds ratio (OR) 0.96, 95% confidence interval (CI): 0.93–0.99). There was no significant effect of HCW vaccination coverage on resident infections and deaths. Campaign participation was associated with decreased odds of infection and death among residents (OR: 0.17, 95% CI: 0.06–0.47 and OR: 0.06, 95% CI: 0.02–0.17 respectively).ConclusionOur analysis suggests that in a context of reinforced IPC measures, influenza still represents a significant burden for NH residents. The most effective measures in decreasing resident influenza burden in NHs was participation in the cantonal influenza vaccination campaign and resident vaccination.

Risk of healthcare visits from influenza in subjects with diabetes and impacts of early vaccination

IntroductionThe objective of this study was to determine the burden of influenza disease in patients with or without diabetes in a population of American adults to understand the benefits of...

Incidence of laboratory-confirmed influenza and RSV and associated presenteeism and absenteeism among healthcare personnel, Israel, influenza seasons 2016 to 2019.

BackgroundHealthcare personnel (HCP) are at high risk for respiratory infections through occupational exposure to respiratory viruses.AimWe used data from a prospective influenza vaccine effectiveness study in HCP to quantify the incidence of acute respiratory infections (ARI) and their associated presenteeism and absenteeism.MethodsAt the start and end of each season, HCP at two Israeli hospitals provided serum to screen for antibodies to influenza virus using the haemagglutination inhibition assay. During the season, active monitoring for the development of ARI symptoms was conducted twice a week by RT-PCR testing of nasal swabs for influenza and respiratory syncytial virus (RSV). Workplace presenteeism and absenteeism were documented. We calculated incidences of influenza- and RSV-associated ARI and applied sampling weights to make estimates representative of the source population.ResultsThe median age of 2,505 participating HCP was 41 years, and 70% were female. Incidence was 9.1 per 100 person-seasons (95% CI: 5.8-14.2) for RT-PCR-confirmed influenza and 2.5 per 100 person-seasons (95% CI: 0.9-7.1) for RSV illness. Each season, 18-23% of unvaccinated and influenza-negative HCP seroconverted. The incidence of seroconversion or RT-PCR-confirmed influenza was 27.5 per 100 person-seasons (95% CI: 17.8-42.5). Work during illness occurred in 92% (95% CI: 91-93) of ARI episodes, absence from work in 38% (95% CI: 36-40).ConclusionInfluenza virus and RSV infections and associated presenteeism and absenteeism were common among HCP. Improving vaccination uptake among HCP, infection control, and encouraging sick HCP to stay home are important strategies to reduce ARI incidence and decrease the risk of in-hospital transmission.

Antivirals for post-exposure prophylaxis of influenza: a systematic review and network meta-analysis

Antiviral post-exposure prophylaxis with neuraminidase inhibitors can reduce the incidence of influenza and the risk of symptomatic influenza, but the efficacy of the other classes of antiviral remains unclear. To support an update of WHO influenza guidelines, this systematic review and network meta-analysis evaluated antiviral drugs for post-exposure prophylaxis of influenza. We systematically searched MEDLINE, Embase, Cochrane Central Register of Controlled Trials, Cumulative Index to Nursing and Allied Health Literature, Global Health, Epistemonikos, and ClinicalTrials.gov for randomised controlled trials published up to Sept 20, 2023 that evaluated the efficacy and safety of antivirals compared with another antiviral or placebo or standard care for prevention of influenza. Pairs of reviewers independently screened studies, extracted data, and assessed the risk of bias. We performed network meta-analyses with frequentist random effects model and assessed the certainty of evidence using the GRADE (Grading of Recommendations Assessment, Development and Evaluation) approach. The outcomes of interest were symptomatic or asymptomatic infection, admission to hospital, all-cause mortality, adverse events related to antivirals, and serious adverse events. This study is registered with PROSPERO, CRD42023466450. Of 11 845 records identified by our search, 33 trials of six antivirals (zanamivir, oseltamivir, laninamivir, baloxavir, amantadine, and rimantadine) that enrolled 19 096 individuals (mean age 6·75-81·15 years) were included in this systematic review and network meta-analysis. Most of the studies were rated as having a low risk of bias. Zanamivir, oseltamivir, laninamivir, and baloxavir probably achieve important reductions in symptomatic influenza in individuals at high risk of severe disease (zanamivir: risk ratio 0·35, 95% CI 0·25-0·50; oseltamivir: 0·40, 0·26-0·62; laninamivir: 0·43, 0·30-0·63; baloxavir: 0·43, 0·23-0·79; moderate certainty) when given promptly (eg, within 48 h) after exposure to seasonal influenza. These antivirals probably do not achieve important reductions in symptomatic influenza in individuals at low risk of severe disease when given promptly after exposure to seasonal influenza (moderate certainty). Zanamivir, oseltamivir, laninamivir, and baloxavir might achieve important reductions in symptomatic zoonotic influenza in individuals exposed to novel influenza A viruses associated with severe disease in infected humans when given promptly after exposure (low certainty). Oseltamivir, laninamivir, baloxavir, and amantadine probably decrease the risk of all influenza (symptomatic and asymptomatic infection; moderate certainty). Zanamivir, oseltamivir, laninamivir, and baloxavir probably have little or no effect on prevention of asymptomatic influenza virus infection or all-cause mortality (high or moderate certainty). Oseltamivir probably has little or no effect on admission to hospital (moderate certainty). All six antivirals do not significantly increase the incidence of drug-related adverse events or serious adverse events, although the certainty of evidence varies. Post-exposure prophylaxis with zanamivir, oseltamivir, laninamivir, or baloxavir probably decreases the risk of symptomatic seasonal influenza in individuals at high risk for severe disease after exposure to seasonal influenza viruses. Post-exposure prophylaxis with zanamivir, oseltamivir, laninamivir, or baloxavir might reduce the risk of symptomatic zoonotic influenza after exposure to novel influenza A viruses associated with severe disease in infected humans. World Health Organization.

Detection of influenza virus in urban wastewater during the season 2022/2023 in Sicily, Italy.

Seasonal influenza generally represents an underestimated public health problem with significant socioeconomic implications. Monitoring and detecting influenza epidemics are important tasks that require integrated strategies. Wastewater-based epidemiology (WBE) is an emerging field that uses wastewater data to monitor the spread of disease and assess the health of a community. It can represent an integrative surveillance tool for better understanding the epidemiology of influenza and prevention strategies in public health. We conducted a study that detected the presence of Influenza virus RNA using a wastewater-based approach. Samples were collected from five wastewater treatment plants in five different municipalities, serving a cumulative population of 555,673 Sicilian inhabitants in Italy. We used the RT-qPCR test to compare the combined weekly average of Influenza A and B viral RNA in wastewater samples with the average weekly incidence of Influenza-like illness (ILI) obtained from the Italian national Influenza surveillance system. We also compared the number of positive Influenza swabs with the viral RNA loads detected from wastewater. Our study investigated 189 wastewater samples. Cumulative ILI cases substantially overlapped with the Influenza RNA load from wastewater samples. Influenza viral RNA trends in wastewater samples were similar to the rise of ILI cases in the population. Therefore, wastewater surveillance confirmed the co-circulation of Influenza A and B viruses during the season 2022/2023, with a similar trend to that reported for the weekly clinically confirmed cases. Wastewater-based epidemiology does not replace traditional epidemiological surveillance methods, such as laboratory testing of samples from infected individuals. However, it can be a valuable complement to obtaining additional information on the incidence of influenza in the population and preventing its spread.