Respiratory syncytial virus in influenza-like illness cases: Epidemiology and molecular analyses of four consecutive winter seasons (2014-2015/2017-2018) in Lombardy (Northern Italy).

BACKGROUND: Besides seasonal influenza viruses (IV), several other pathogens-including respiratory syncytial virus (RSV)-are involved in clinically undistinguished influenza-like illnesses (ILIs). This study aimed at investigating the contribution of RSV in ILI cases in Lombardy (Northern Italy) during four consecutive winter seasons. MATERIALS AND METHODS: In the framework of influenza surveillance, respiratory samples from ILI outpatients were collected from 2014-2015 to 2017-2018 season. IV-negative swabs were included in the study and analyzed to detect and molecularly characterize RSV-A and RSV-B. RESULTS: A total of 12.9% (135/1047) of samples were positive to RSV that was mostly detected among children ≤5 years (51/183, 27.8%) and those aged 6 to 15 years (30/158, 18.9%), whereas elderly >65 years accounted for 12% of RSV cases (15/125). The median start of RSV epidemic was in the end of November, with a peak in mid-February and a width of nearly 4 months, almost overlapping seasonal influenza epidemic. RSV-A and RSV-B co-circulated in all considered seasons, with RSV-B predominating on RSV-A (63.6% vs 36.4%; P < .001). Most (85.2%) RSV-A belonged to genotype ON1 and the remaining to NA1. All RSV-B clustered within the BA genotype. CONCLUSIONS: In this study, RSV significantly contributed to ILI cases, especially among pediatric population (<15 years), although it was detected in all age groups. RSV-B predominated on RSV-A, and the most recent evolved genotypes (BA and ON1, respectively) circulated. Investigating the epidemiological and molecular characteristics of RSV in ILI cases can increase baseline epidemiological information before the introduction of RSV vaccination.

Molecular Characterization of Influenza Strains in Patients Admitted to Intensive Care Units during the 2017-2018 Season.

This study aimed at assessing the frequency and the distribution of influenza virus types/subtypes in 172 laboratory-confirmed influenza-positive patients admitted to intensive care units (ICUs) during the 2017-2018 season in the Lombardy region (Northern Italy), and to investigate the presence of molecular pathogenicity markers. A total of 102/172 (59.3%) patients had influenza A infections (83 A/H1N1pdm09, 2 H3N2 and 17 were untyped), while the remaining 70/172 (40.7%) patients had influenza B infections. The 222G/N mutation in the hemagglutinin gene was identified in 33.3% (3/9) of A/H1N1pdm09 strains detected in the lower respiratory tract (LRT) samples and was also associated with more severe infections, whereas no peculiar mutations were observed for influenza B strains. A single-point evolution was observed in site 222 of A/H1N1pdm09 viruses, which might advantage viral evolution by favouring virus binding and replication in the lungs. Data from 17 paired upper respiratory tract (URT) and LRT samples showed that viral load in LRT samples was mostly higher than that detected in URT samples. Of note, influenza viruses were undetectable in 35% of paired URT samples. In conclusion, LRT samples appear to provide more accurate clinical information than URT samples, thus ensuring correct diagnosis and appropriate treatment of patients with severe respiratory infections requiring ICU admission.

Epidemiology and molecular characterization of influenza viruses, human parechoviruses and enteroviruses in children up to 5 years with influenza-like illness in Northern Italy during seven consecutive winter seasons (2010-2017).

Besides the influenza virus (IV), several other viruses are responsible for influenza-like illness (ILI). Although human parechoviruses (HPeVs) and enteroviruses (EVs) may impact on ILI, limited data on their epidemiological characteristics are available. During seven consecutive winter seasons (from 2010-2011 to 2016-2017), within the framework of an influenza surveillance system (InfluNet), 593 respiratory swabs were collected from children ≤5 years of age with ILIs. Molecular detection showed that 58.3 % of swabs were positive for at least one of the viruses under study: 46 % for IV, 13 % for EV and 5.4 % for HPeV. A single virus was identified in 51.3 % of samples while more than one virus was detected in 7 % of the samples. The risk of contracting IV was higher than the risk associated with EV, which in turn was higher than the risk of contracting HPeV. The risk of developing an IV infection was twofold greater in children >3 years than in those ≤3 years, who had higher risk of EV/HPeV infection. The frequency of EV/HPeV-positive swabs increased significantly during the 2016-2017 winter season compared to the previous six seasons. Sixteen EV genotypes were identified belonging to species A and B. HPeV-1 was the most frequently detected genotype, followed by -6 and -3. In this study, IV was mainly responsible for ILI, however EV and HPeV were also involved and particularly affected children ≤3 years of age. Influenza surveillance samples could provide us with valuable insight into the epidemiological features of viruses involved in ILI.

Long-term patterns of humoral and cellular response after vaccination against influenza A (H1N1) in patients with hematologic malignancies.

OBJECTIVES: The efficacy of a novel vaccine against influenza virus A (H1N1) in patients with hematologic malignancies is largely unknown. METHODS: We prospectively evaluated the humoral and cellular immune responses after one injection of monovalent adjuvanted 2009 H1N1 vaccine in 47 adults with hematologic malignancies and 77 controls by hemagglutination-inhibition assay and flow-cytometry analysis on day 0, 28, 50, and 90. RESULTS: On day 28 postvaccination, patients had lower seroprotection (95.2% vs. 75.2%, P < 0.01) and seroconversion (88.7% vs. 51.1%, P < 0.01) rates, as well as geometric mean titer (GMT; 256 vs. 134, P < 0.05), relative to controls. Response to vaccination varied according to the evaluated time point and the patient status: Patients not receiving chemotherapy had seroprotection and GMTs similar to controls in all time points, while patients receiving chemotherapy or allogeneic hematopoietic stem cell transplant (HSCT) had lower seroprotection and seroconversion levels than controls on day 28 and 50. EMEA cutoffs for efficacy were reached from day 28 by patients in follow-up or under treatment and only from day 90 by those with HSCT, especially if still under immunosuppressants. Patients treated with immunomodulatory drugs had higher antibody responses in terms of seroprotection and GMTs. T- and NK cell-mediated responses mounted from day 50 and did not differ between patients and controls. CONCLUSIONS: According to EMEA recommendation, H1N1 vaccination strategy was effective at protecting most of the hematologic patients, but needed to be improved in those more immunocompromised.

Respiratory syncytial virus in pediatric influenza-like illness cases in Lombardy, Northern Italy, during seven consecutive winter seasons (from 2014-2015 to 2020-2021).

INTRODUCTION: Respiratory syncytial virus (RSV) is the major cause of lower respiratory tract illness in young children and can also cause influenza-like illness (ILI). Here we investigated the epidemiological features of RSV infection in pediatric ILI cases in Lombardy (a region in Northern Italy accounting nearly 10 million inhabitants) from 2014-2015 to 2020-2021 winter seasons. MATERIAL AND METHODS: Data for this study were retrieved and statistically analyzed from the database of virological influenza surveillance of the regional reference laboratory for Lombardy within the Italian influenza surveillance network (InfluNet). RESULTS: RSV accounted for nearly 19% of pediatric ILI with a risk of infection nearly two-fold greater than that of individuals ≥15 years. RSV positivity rate increased to 28% considering 0-5 years old children. Although in children ≤5 years the risk of infection from influenza viruses resulted nearly two-fold higher than the risk of RSV infection, the age group 4-6 months and 7-12 months showed a five-fold greater risk of infection from RSV than from influenza. Children ≤5 years of age with pre-existing underlying health conditions had a nearly five-fold greater risk of getting RSV infection than otherwise healthy 0-5 years old children. RSV was identified in ILI cases <15 years of age in all considered winter seasons except in the 2020-2021 season. DISCUSSION: Sentinel surveillance of ILI allowed us to identify groups at higher risk of RSV and influenza infection and to define the start, duration, timing, and intensity of the RSV and influenza community circulation. This surveillance approach can be implemented to assess the RSV circulation and impact in a real-time manner.

When the COVID-19 Pandemic Surges during Influenza Season: Lessons Learnt from the Sentinel Laboratory-Based Surveillance of Influenza-Like Illness in Lombardy during the 2019-2020 Season.

This paper outlines the role of Lombardy's regional influenza reference laboratory (Northern Italy) in the surveillance of influenza-like illnesses (ILIs) in monitoring SARS-CoV-2 circulation by analyzing 631 consecutive nasopharyngeal swabs (NPSs) collected from ILI outpatients by sentinel physicians during the 2019-2020 season. The samples were tested by specific real-time RT-PCRs targeting SARS-CoV-2, influenza viruses, and RSVs. Results: Of these NPSs, 31% tested positive for influenza viruses, 10% for SARS-CoV-2, and 7% for RSV. No coinfections were detected. Influenza viruses and RSVs circulated throughout the surveillance period until the end of February (week 9-2020), when they suddenly ceased to circulate seven weeks earlier than during the previous five influenza seasons. After the first detection of SARS-CoV-2 in our ILI outpatients at the beginning of March (week 10-2020), SARS-CoV-2 remained the only virus identified throughout the surveillance period. Patients ≥ 65 years had a 3.2-fold greater risk of being infected with SARS-CoV-2, while school-age children (5-14 years) and children < 5 years proved to be the age groups most at risk of contracting influenza viruses and RSV, respectively. Our experience demonstrates that laboratory-based ILI surveillance networks are essential for identifying SARS-CoV-2 cases that would otherwise remain undetected, in order to stop their spread within our communities.

Influenza Vaccination in Italian Healthcare Workers (2018-2019 Season): Strengths and Weaknesses. Results of a Cohort Study in Two Large Italian Hospitals.

BACKGROUND: Annual vaccination is the most effective way to combat influenza. As influenza viruses evolve, seasonal vaccines are updated annually. Within the European project Development of Robust and Innovative Vaccine Effectiveness (DRIVE), a cohort study involving Italian healthcare workers (HCWs) was carried out during the 2018-2019 season. Two aims were defined: to measure influenza vaccine effectiveness (IVE) against laboratory-confirmed influenza cases and to conduct an awareness-raising campaign to increase vaccination coverage. METHODS: Each subject enrolled was followed up from enrollment to the end of the study. Each HCW who developed ILI was swabbed for laboratory confirmation of influenza. Influenza viruses were identified by molecular assays. A Cox regression analysis, crude and adjusted for confounding variables, was performed to estimate the IVE. RESULTS: Among the 4483 HCWs enrolled, vaccination coverage was 32.5%, and 308 ILI cases were collected: 23.4% were positive for influenza (54.2% A(H1N1) pdm09; 45.8% A(H3N2)). No influenza B viruses were detected. No overall IVE was observed. Analyzing the subtypes of influenza A viruses, the IVE was estimated as 45% (95% CI: -59 to 81) for A(H1N1) pdm09. CONCLUSIONS: Vaccination coverage among HCWs increased. Study difficulties and the circulation of drifted variants of A(H3N2) could partly explain the observed IVE.

Rationale for the clinical use of a ribosome-component immune modulator.

Vaccines have long been used to boost the immune system and to confer protection against microbial infections. In contrast, immunotherapy based on ribosomal preparations has been proposed to enhance both specific and nonspecific immune responses (in particular, the mucosal immune defense system) against common respiratory tract pathogens. The aim of this review is to summarize current knowledge on the ability of a combination of four immunogenic ribosomal fractions from different bacteria species and of the extracted fraction from the membrane of Klebsiella pneumoniae to modulate several immune functions. The immunomodulatory activity of the ribosome component is attributed to the presence of highly purified epitopes from cellular fractions obtained by bacterial lysis. The ribosomal preparation is hypothesized to induce a T-dependent immune response consequent network with proliferation of B lymphocytes and production of secretory high-affinity antibodies (in particular, IgA), as well as the creation of a specific immune memory. Indeed, this agent stimulates the activity of macrophages, polymorphonuclear cells, and natural killer cells. The "ideal" vaccine is a highly purified protein bound to a carrier and an adjuvant that enhances the vaccination effect.

Molecular characterization of influenza viruses circulating in Northern Italy during two seasons (2005/2006 and 2006/2007) of low influenza activity.

The influenza activity and circulation of influenza viruses in Lombardy (the most populous Italian region) were observed during two consecutive seasons (2005/2006 and 2006/2007) characterized by low influenza activity by the Italian Influenza Surveillance Network. The molecular characteristics of circulating viruses were analyzed to evaluate the introduction of new variants and emergence of vaccine-escape viruses. In both seasons, the epidemic in Lombardy was sustained almost exclusively by influenza A viruses, accounting for 80.5% and 93.6% of total detections, respectively, and the co-circulation of A/H3 viruses belonging to distinct phylogenetic groups was observed. The A/H1N1 viruses isolated during the 2005/2006 season were closely related to A/New Caledonia/20/99, while the hemagglutinin (HA) sequences of the A/H1N1 viruses from the 2006/2007 season exhibited a greater diversity. These viruses were A/Solomon Islands/3/2006-like and showed several variants. All B isolates were similar to B/Malaysia/2506/2004 belonging to the B/Victoria/2/87-lineage. Influenza B virus was the dominant virus in Europe in the 2005/2006 season and accounted for the 20% of total detections in Lombardy. Overall, the viruses studied presented heterogeneity in their HA sequences suggesting the circulation of a miscellaneous set of variants during the two seasons notwithstanding the medium-low activity of influenza. The importance of virological surveillance of influenza viruses is recognized widely and the molecular characterization of the viruses, especially in vaccinated subjects, is of particular importance to evaluate the introduction and circulation of new variants.

A new chance of preventing winter diseases by the administration of synbiotic formulations.

BACKGROUND: The efficacy of probiotics is currently well documented with regard to the improvement of gastrointestinal functions, whereas their potential role in the prevention of infectious respiratory diseases has not been sufficiently analyzed. PURPOSE OF THE STUDY AND METHODS: A 3-stage prospective, randomized, double blind, placebo-controlled study was carried out with several synbiotic preparations containing 3 to 5 strains of Lactobacillus plantarum, Lactobacillus rhamnosus, and Bifidobacterium lactis, lactoferrin and prebiotics such as either FOS (short-chain fructooligosaccharides) or GOS (galactooligosaccharides). The study was performed over 3 different winter seasons between 2003 and 2007, and was aimed at assessing the ability of the different preparations to improve intestinal functions and to increase the body's defences against respiratory infections. In 2003/04 (stage 1; 237 healthy volunteers) an active formulation (A) containing 3 probiotic strains and FOS was used versus placebo; in 2005/06 (stage 2; 234 healthy volunteers) the same formulation versus a similar preparation enriched with lactoferrin (B), and versus placebo; in 2006/07 (stage 3; 250 healthy volunteers), 2 new synbiotic formulations each containing 5 probiotics and FOS (C) or GOS (D), respectively, versus placebo. RESULTS: In stage 1, bowel functions improved (P=0.004) in terms of reduced bloating and more regular intestinal motility. The length of acute respiratory infection episodes considered as a whole (-0.97 d; P=0.007) and upper respiratory tract infections (URTIs, -1.96 d; P=0.044) were significantly decreased in the synbiotic group. The severity of episodes recorded a statistically significant drop in both episodes considered as a whole (3.21 average score vs. 3.98 in the placebo group, P<0.001) and in URTI (2.56 vs. 3.82; P=0.004) and flu classes (3.80 vs. 4.67, P=0.001). In stage 2, improvement of bowel functions was statistically significant (P=0.005) in synbiotic preparation A. A statistically significant reduction in the number of respiratory tract infections episodes was noted with both the two active formulations (P=0.002 in group A and P=0.003 in group B). The duration of episodes considered as a whole (-1.12 d in one of the 2 active formulation groups; P=0.005), URTIs (-2.08 d in group A; P=0.036) and influenza-like illness episodes (-1.40 d in group A; P=0.049) was significantly decreased in the synbiotic group. A reduction trend in cold episodes was also recorded. The severity of episodes recorded a statistically significant drop in episodes considered as a whole (-0.73 in group A, P=0.003; -0.65 in group B, P=0.004) and in the case of flu (-1.25 in group A, P<0.001; -1.18 in group B, P<0.001). In stage 3, the improvement of bowel functions was confirmed for both active formulations (P<0.001). A significant decrease in the total length of respiratory episodes (-1.51 d; P<0.001 in the group C and -1.39 d; P<0.001 in the group D) and in the length of cough (-3.08 d; P<0.001 in group C; -2.83 d; P<0.001 in group D), cold (-1.02 d; P=0.019 in group C; -1.32 d; P=0.001 in group D) and flu episodes was reported. The severity of episodes recorded a statistically significant drop in regard to episodes considered as a whole, the cold and flu classes in both groups and for cough too in group C. The number of episodes also dropped considerably in terms of overall episodes, cold (group C) and flu. CONCLUSIONS: These results demonstrate that a regular, long-term intake of various synbiotics may improve health by reducing the incidence and severity of respiratory diseases during the cold season.

Ten years (2004-2014) of influenza surveillance in Northern Italy.

As the regional influenza reference centre operating within the Italian network InfluNet, here we report data on virological and epidemiological surveillance of influenza, as well as on the vaccination coverage rates achieved in Lombardy (Northern Italy) over 10 consecutive winter seasons (2004-2014).   Over the past 10 years, influenza vaccine coverage declined both in the general population (from 15.7% in 2004-2005 to 11.7% in 2013-2014) and in the vaccine-target population of individuals ≥65-y-of-age (from 65.3% in 2004-2005 to 48.6% in 2013-2014) and is far below the minimum planned threshold level (75%). The highest influenza-like illness (ILI) rates were recorded during the 2004-2005 and 2009-2010 epidemics (peak incidence: 12.04‰ and 13.28‰, respectively). Both seasons were characterised by the introduction of novel viral strains: A/Fujian/411/2002(H3N2) (a drifted hemagglutinin variant) and A/California/7/2009(H1N1) pandemic virus (a swine origin quadruple reassortant), respectively. Because the antigenic match between vaccine and circulating strains was good in both of these seasons, a relevant proportion of cases may have been prevented by vaccination. A different situation was observed during the 2011-2012 season, when ILI morbidity rates in individuals ≥65-y-of-age were 1.5-6-fold higher than those registered during the other epidemics under review. The higher morbidity resulted from the circulation during the 2011-2012 season of an A/Victoria/361/2011(H3N2)-like variant that presented a reduced genetic match with the A(H3N2) strain included in the 2011-2012 vaccine composition. The continuous surveillance of the characteristics of circulating viruses is an essential tool for monitoring their matching with seasonal vaccine strains. Strategies to increase coverage rates are warranted.

Surveillance of influenza viruses in the post-pandemic era (2010-2012) in Northern Italy.

The activity and circulation of influenza viruses in Lombardy - Northern Italy - (a region with nearly 10 out of the 60 million inhabitants of Italy) were investigated during two consecutive seasons (2010-2011 and 2011-2012), as part of the Italian Influenza Surveillance Network. The molecular characteristics of the hemagglutinin (HA) sequence of circulating viruses were analyzed to investigate the emergence of influenza viral variants. In the surveyed area, the influenza activity of these two post-pandemic seasons was similar in terms of both time frame and impact. The timing of the influenza epidemics was similar to the timing seen prior to the emergence of the pandemic A(H1N1) virus in 2009. A(H1N1)pdm09 was the predominant virus circulating during the 2010-2011 post-pandemic season and then--unexpectedly--almost disappeared. The HA sequences of these A(H1N1)pdm09 viruses segregated in a different genetic group with respect to those identified during the 2009 pandemic, although they were still closely related to the vaccine viral strain A/California/07/2009. Influenza A(H3N2) viruses were the predominant viruses circulating during the 2011-2012 season, accounting for nearly 88% of influenza viruses identified. All HA sequences of the A(H3N2) viruses isolated in the 2011-2012 season fell into the A/Victoria/208/2009 genetic clade (although the A/Perth/16/2009 virus was the reference vaccine strain). B viruses presented with a mixed circulation of viral variants during these two seasons: viruses belonging to both B/Victoria and B/Yamagata lineages co-circulated in different proportions, with a notable rise in the proportion of B/Yamagata viruses (B/Wisconsin/1/2010-like) during the 2011-2012 epidemic. In conclusion, the continuous monitoring of the characteristics of circulating viruses is an essential tool for understanding the epidemiological and virological features of influenza viruses, for monitoring their matching with seasonal vaccine strains, and for tuning vaccination strategies.

Genetic drift influenza A(H3N2) virus hemagglutinin (HA) variants originated during the last pandemic turn out to be predominant in the 2011-2012 season in Northern Italy.

Influenza A(H3N2) virus is once again the predominant strain after the 2009 pandemic. Its molecular epidemiology and phylogeny were investigated during the 2011-2012 season in Northern Italy. The epidemiological and virological influenza surveillance was carried out within the framework of the Italian Influenza Surveillance Network. The hemagglutinin (HA) gene of the A(H3N2) viruses detected was analyzed by means of a time-scaled phylogenetic approach. In Northern Italy, the 2011-2012 epidemic wave was sustained almost exclusively by influenza A(H3N2) viruses (87.2% of total influenza virus detections). The consultation rates for influenza-like illness (ILI) in the age group ≥65 years were 1.5 to 6-fold higher than those registered during the previous eight epidemics: A(H3N2) was the only virus identified in this group. The phylogenetic analysis of A(H3N2) viruses showed viruses belonging to the A/Victoria/208/2009 genetic clade, characterized by substitutions in HA antigenic sites with respect to the A/Perth/16/2009-like 2011-2012 vaccine strain. About one-third of analyzed sequences fell into group 6 and two thirds into group 3 (subdivided into 3A, 3B, and 3C). The time scale reconstruction of the phylogeny showed several independent introductions of A(H3N2) groups between summer and winter of 2011. However, the common origin of all the circulating A(H3N2) strains dated back to the 2009 pandemic period (November 2009). The time scale phylogenetic approach is of particular importance for the evaluation of the introduction and circulation of new variants in the area. Therefore, it should be implemented within the framework of influenza virological surveillance.

Response to 2009 pandemic and seasonal influenza vaccines co-administered to HIV-infected and HIV-uninfected former drug users living in a rehabilitation community in Italy.

BACKGROUND: 2009 A(H1N1) pandemic influenza vaccination was recommended as a priority to essential workers and high-risk individuals, including HIV-infected patients and people living in communities. METHODS: HIV-infected and HIV-uninfected former drug-users (18-60 years old) living in a rehabilitation community (San Patrignano, Italy) received one dose of a MF59-adjuvanted 2009 pandemic influenza vaccine and one dose of a 2009-2010 seasonal trivalent inactivated influenza vaccine (containing A/Brisbane/59/2007(H1N1), A/Brisbane/10/2007(H3N2), B/Brisbane/60/2008) simultaneously. Antibodies against each vaccine antigen were determined at the time of vaccination and one and six months post-vaccination by hemagglutination-inhibition test. RESULTS: 49 HIV-infected and 60 HIV-uninfected subjects completed the study. Most (98%) HIV-infected participants were on antiretroviral treatment, the median CD4+ cell count was 350 (IQR 300)cells/µl and viremia was suppressed in 91.8% of cases. One month post-vaccination, no significant changes in immune-virological parameters were observed. One month post-vaccination, the immune responses to both pandemic and seasonal vaccine met the EMA-CPMP criteria for immunogenicity of influenza vaccines in both HIV-infected and HIV-uninfected subjects. No difference in vaccine responses was observed between the two groups. Six months after vaccination, the percentages of vaccinees with antibody titres ≥1:40 and antibody geometric mean titres significantly decreased in both groups. However, they were significantly lower in HIV-infected than in HIV-uninfected vaccinees. In subjects who had been primed to seasonal influenza the year before (through either vaccination or natural infection), levels of antibodies against 2009 A(H1N1) were higher than those measured in unprimed subjects, both one month and six months post-vaccination. CONCLUSIONS: The co-administration of a single dose of 2009 pandemic MF59-adjuvanted influenza vaccine with a seasonal vaccine provided a protective immune response in both HIV-infected and HIV-uninfected individuals. Subjects who had been primed to seasonal influenza in the year preceding the pandemic had a more vigorous and long-lasting antibody response to 2009 pandemic vaccine.

Influenza virological surveillance in children: the use of the QuickVue rapid diagnostic test.

New rapid diagnostic methods are needed to identify influenza infections to improve virological surveillance usually undertaken with conventional time-consuming, complex, and even expensive laboratory methods. Another reason for using a rapid test is to avoid inappropriate therapy, particularly in children, where use of antibiotics inappropriately and high influenza-related rates of hospitalisation are described. During two winter seasons, the performance of the QuickVue Influenza test (QV) was evaluated in children under 14 presenting with influenza like illness, and compared the results with those obtained from sentinel network surveillance using standard protocols for the sample collection and the laboratory analysis by virus culture and reverse transcription-polymerase chain reaction (RT-PCR). During the first influenza season (2000/2001), 22 paediatricians collected one nose- and one throat-swab from each of the 586 children 0-6 years old recruited in the study. The QV test was carried out in the physician's office by primary care staff on the nose swab material. When compared with virus culture of the throat swab, the QV test had a sensitivity of 36.5%. In the following 2001/2002-influenza season, the performance of the QV test as a rapid laboratory screening assay was assessed. 342 children aged 0-14 years were enrolled with only one throat swab collected from each patient and sent to the laboratory where the QV, virus culture, and RT-PCR tests were performed. The results showed a better sensitivity (54.5%) of the test in comparison with virus culture and RT-PCR assays. The data indicate that rapid QV testing in the physician office setting, using these easily obtained samples, may be too insensitive to be useful for surveillance and for immediate clinical management of children presenting with influenza-like illness. Nevertheless, the QV test may be a valuable diagnostic tool if used in laboratory, as a rapid screening test.