Household Transmission of Influenza A Viruses in 2021-2022.

Importance: Influenza virus infections declined globally during the COVID-19 pandemic. Loss of natural immunity from lower rates of influenza infection and documented antigenic changes in circulating viruses may have resulted in increased susceptibility to influenza virus infection during the 2021-2022 influenza season. Objective: To compare the risk of influenza virus infection among household contacts of patients with influenza during the 2021-2022 influenza season with risk of influenza virus infection among household contacts during influenza seasons before the COVID-19 pandemic in the US. Design, Setting, and Participants: This prospective study of influenza transmission enrolled households in 2 states before the COVID-19 pandemic (2017-2020) and in 4 US states during the 2021-2022 influenza season. Primary cases were individuals with the earliest laboratory-confirmed influenza A(H3N2) virus infection in a household. Household contacts were people living with the primary cases who self-collected nasal swabs daily for influenza molecular testing and completed symptom diaries daily for 5 to 10 days after enrollment. Exposures: Household contacts living with a primary case. Main Outcomes and Measures: Relative risk of laboratory-confirmed influenza A(H3N2) virus infection in household contacts during the 2021-2022 season compared with prepandemic seasons. Risk estimates were adjusted for age, vaccination status, frequency of interaction with the primary case, and household density. Subgroup analyses by age, vaccination status, and frequency of interaction with the primary case were also conducted. Results: During the prepandemic seasons, 152 primary cases (median age, 13 years; 3.9% Black; 52.0% female) and 353 household contacts (median age, 33 years; 2.8% Black; 54.1% female) were included and during the 2021-2022 influenza season, 84 primary cases (median age, 10 years; 13.1% Black; 52.4% female) and 186 household contacts (median age, 28.5 years; 14.0% Black; 63.4% female) were included in the analysis. During the prepandemic influenza seasons, 20.1% (71/353) of household contacts were infected with influenza A(H3N2) viruses compared with 50.0% (93/186) of household contacts in 2021-2022. The adjusted relative risk of A(H3N2) virus infection in 2021-2022 was 2.31 (95% CI, 1.86-2.86) compared with prepandemic seasons. Conclusions and Relevance: Among cohorts in 5 US states, there was a significantly increased risk of household transmission of influenza A(H3N2) in 2021-2022 compared with prepandemic seasons. Additional research is needed to understand reasons for this association.

Circulation and seasonality of influenza viruses in different transmission zones in Africa.

BACKGROUND: Influenza is responsible for more than 5 million severe cases and 290,000 to 650,000 deaths every year worldwide. Developing countries account for 99% of influenza deaths in children under 5 years of age. This paper aimed to determine the dynamics of influenza viruses in African transmission areas to identify regional seasonality for appropriate decision-making and the development of regional preparedness and response strategies. METHODS: We used data from the WHO FluMart website collected by National Influenza Centers for seven transmission periods (2013-2019). We calculated weekly proportions of positive influenza cases and determined transmission trends in African countries to determine the seasonality. RESULTS: From 2013 to 2019, influenza A(H1N1)pdm2009, A(H3N2), and A(H5N1) viruses, as well as influenza B Victoria and Yamagata lineages, circulated in African regions. Influenza A(H1N1)pdm2009 and A(H3N2) highly circulated in northern and southern Africa regions. Influenza activity followed annual and regional variations. In the tropical zone, from eastern to western via the middle regions, influenza activities were marked by the predominance of influenza A subtypes despite the circulation of B lineages. One season was identified for both the southern and northern regions of Africa. In the eastern zone, four influenza seasons were differentiated, and three were differentiated in the western zone. CONCLUSION: Circulation dynamics determined five intense influenza activity zones in Africa. In the tropics, influenza virus circulation waves move from the east to the west, while alternative seasons have been identified in northern and southern temperate zones. Health authorities from countries with the same transmission zone, even in the absence of local data based on an established surveillance system, should implement concerted preparedness and control activities, such as vaccination.

No evidence of SARS-CoV-2 in hospitalized patients with severe acute respiratory syndrome in five Italian hospitals from 1st November 2019 to 29th February 2020.

BACKGROUND: On 9th January 2020, China CDC reported a novel coronavirus (later named SARS-CoV-2) as the causative agent of the coronavirus disease 2019 (COVID-19). Identifying the first appearance of virus is of epidemiological importance to tracking and mapping the spread of SARS-CoV-2 in a country. We therefore conducted a retrospective observational study to detect SARS-CoV-2 in oropharyngeal samples collected from hospitalized patients with a Severe Acute Respiratory Infection (SARI) enrolled in the DRIVE (Development of Robust and Innovative Vaccine Effectiveness) study in five Italian hospitals (CIRI-IT BIVE hospitals network) (1st November 2019 - 29th February 2020). OBJECTIVES: To acquire new information on the real trend in SARS-CoV-2 infection during pandemic phase I and to determine the possible early appearance of the virus in Italy. MATERIALS AND METHODS: Samples were tested for influenza [RT-PCR assay (A/H1N1, A/H3N2, B/Yam, B/Vic)] in accordance with the DRIVE study protocol. Subsequently, swabs underwent molecular testing for SARS-COV-2. [one-step real-time multiplex retro-transcription (RT) PCR]. RESULTS: In the 1683 samples collected, no evidence of SARS-CoV-2 was found. Moreover, 28.3% (477/1683) of swabs were positive for influenza viruses, the majority being type A (358 vs 119 type B). A/H3N2 was predominant among influenza A viruses (55%); among influenza B viruses, B/Victoria was prevalent. The highest influenza incidence rate was reported in patients aged 0-17 years (40.3%) followed by those aged 18-64 years (24.4%) and ≥65 years (14.8%). CONCLUSIONS: In Italy, some studies have shown the early circulation of SARS-CoV-2 in northern regions, those most severely affected during phase I of the pandemic. In central and southern regions, by contrast no early circulation of the virus was registered. These results are in line with ours. These findings highlight the need to continue to carry out retrospective studies, in order to understand the epidemiology of the novel coronavirus, to better identify the clinical characteristics of COVID-19 in comparison with other acute respiratory illnesses (ARI), and to evaluate the real burden of COVID-19 on the healthcare system.

Influenza A(H3N2) Outbreak on a University Campus - Michigan, October-November 2021.

On November 10, 2021, the Michigan Department of Health and Human Services (MDHHS) was notified of a rapid increase in influenza A(H3N2) cases by the University Health Service (UHS) at the University of Michigan in Ann Arbor. Because this outbreak represented some of the first substantial influenza activity during the COVID-19 pandemic, CDC, in collaboration with the university, MDHHS, and local partners conducted an investigation to characterize and help control the outbreak. Beginning August 1, 2021, persons with COVID-19-like* or influenza-like illness evaluated at UHS received testing for SARS-CoV-2, influenza, and respiratory syncytial viruses by rapid multiplex molecular assay.† During October 6-November 19, a total of 745 laboratory-confirmed influenza cases were identified.§ Demographic information, genetic characterization of viruses, and influenza vaccination history data were reviewed. This activity was conducted consistent with applicable federal law and CDC policy.¶.

Circulation patterns of human seasonal Influenza A viruses in Chile before H1N1pdm09 pandemic.

Understanding the diversity and circulation dynamics of seasonal influenza viruses is key to public health decision-making. The limited genetic information of pre-pandemic seasonal IAVs in Chile has made it difficult to accurately reconstruct the phylogenetic relationships of these viruses within the country. The objective of this study was to determine the genetic diversity of pre-pandemic human seasonal IAVs in Chile. We sequenced the complete genome of 42 historic IAV obtained between 1996 and 2007. The phylogeny was determined using HA sequences and complemented using other segments. Time-scale phylogenetic analyses revealed that the diversity of pre-pandemic human seasonal IAVs in Chile was influenced by continuous introductions of new A/H1N1 and A/H3N2 lineages and constant viral exchange between Chile and other countries every year. These results provide important knowledge about genetic diversity and evolutionary patterns of pre-pandemic human seasonal IAVs in Chile, which can help design optimal surveillance systems and prevention strategies. However, future studies with current sequences should be conducted.

Characterization of Canine Influenza Virus A (H3N2) Circulating in Dogs in China from 2016 to 2018.

Avian H3N2 influenza virus follows cross-host transmission and has spread among dogs in Asia since 2005. After 2015-2016, a new H3N2 subtype canine influenza epidemic occurred in dogs in North America and Asia. The disease prevalence was assessed by virological and serological surveillance in dogs in China. Herein, five H3N2 canine influenza virus (CIV) strains were isolated from 1185 Chinese canine respiratory disease samples in 2017-2018; these strains were on the evolutionary branch of the North American CIVs after 2016 and genetically far from the classical canine H3N2 strain discovered in China before 2016. Serological surveillance showed an HI antibody positive rate of 6.68%. H3N2 was prevalent in the coastal areas and northeastern regions of China. In 2018, it became the primary epidemic strain in the country. The QK01 strain of H3N2 showed high efficiency in transmission among dogs through respiratory droplets. Nevertheless, the virus only replicated in the upper respiratory tract and exhibited low pathogenicity in mice. Furthermore, highly efficient transmission by direct contact other than respiratory droplet transmission was found in a guinea pig model. The low-level replication in avian species other than ducks could not facilitate contact and airborne transmission in chickens. The current results indicated that a novel H3N2 virus has become a predominant epidemic strain in dogs in China since 2016 and acquired highly efficient transmissibility but could not be replicated in avian species. Thus, further monitoring is required for designing optimal immunoprophylactic tools for dogs and estimating the zoonotic risk of CIV in China.

Fatal case of simply influenza A (H3N2)-associated encephalitis in immunocompetent patient.

Influenza virus-associated encephalopathy/encephalitis is a rare entity in adults that can lead to severe neurological sequelae and even death. The clinical presentation can be quite diverse. This absence of a typical presentation along with the difficulty detecting the virus in the cerebrospinal fluid represents a diagnostic challenge. We present the case of a 79-year-old male with sudden onset of decreased consciousness and signs of right hemisphere damage. The presence of influenza A (H3N2) virus in respiratory sample along with compatible findings in cranial magnetic resonance led to the diagnosis. The patient died without responding to treatment with antivirals and immunomodulators and the anatomopathological study did not detect infectious agent. Early diagnostic suspicion is essential to establish adequate treatment and improve the prognosis.

The first epidemiological and virological influenza surveillance in the Republic of Guinea revealed the predominance of influenza A/H3N2 and B Victoria viruses.

Little is known about respiratory viruses infection in Guinea. Influenza surveillance has not been implemented in Guinea mainly because of the paucity of laboratory infrastructure and capacity. This paper presents the first influenza surveillance data in Guinea.Swabs were obtained from August 2018 through December 2019 at influenza sentinel sites and transported to the Institut National de Santé Publique for testing. Ribonucleic acid was extracted and tested for the presence of influenza A and B by real-time reverse transcription-polymerase chain reaction (RT-PCR). Positive samples were further characterised to determine the subtypes and lineages of influenza viruses.A total of 862 swabs were collected and tested. Twenty-three per cent of samples tested positive for influenza A and B viruses. Characterisation of positive specimens identified influenza A/H1N1pmd09 (2.5%), influenza A/H3N2 (57.3%), influenza B/Victoria lineage (36.7%) and 7 (3.5%) influenza B with undetermined lineage. Influenza B virus activity clustered in August through November while influenza A/H3N2 displayed two clusters of activities that appeared in May through August and November through December.For the first time in Guinea, the epidemiology, diversity and period of circulation of influenza viruses were studied. The results indicate the predominance and the periods of activities of influenza B Victoria lineage and influenza A/H3N2 which are important information for preventive strategies. It is warranted to extend the influenza surveillance to other parts of Guinea to better understand the epidemiology of the viruses and monitor the emergence of influenza strains with pandemic potential.

Stability of HA2 Prefusion Structure and pH-Induced Conformational Changes in the HA2 Domain of H3N2 Hemagglutinin.

Influenza hemagglutinin is the fusion protein that mediates fusion of the viral and host membranes through a large conformational change upon acidification in the developing endosome. The "spring-loaded" model has long been used to describe the mechanism of hemagglutinin and other type 1 viral glycoproteins. This model postulates a metastable conformation of the HA2 subunit, caged from adopting a lower-free energy conformation by the HA1 subunit. Here, using a combination of biochemical and spectroscopic methods, we study a truncated construct of HA2 (HA2*, lacking the transmembrane domain) recombinantly expressed in Escherichia coli as a model for HA2 without the influence of HA1. Our data show that HA2* folds into a conformation like that of HA2 in full length HA and forms trimers. Upon acidification, HA2* undergoes a conformational change that is consistent with the change from pre- to postfusion HA2 in HA. This conformational change is fast and occurs on a time scale that is not consistent with aggregation. These results suggest that the prefusion conformation of HA2 is stable and the change to the postfusion conformation is due to protonation of HA2 itself and not merely uncaging by HA1.

Self-Assembled Chromogenic Polymeric Nanoparticle-Laden Nanocarrier as a Signal Carrier for Derivative Binary Responsive Virus Detection.

In the current biosensor, the signal generation is limited to single virus detection in the reaction chamber. An adaptive strategy is required to enable the recognition of multiple viruses for diagnostics and surveillance. In this work, a nanocarrier is deployed to bring specific signal amplification into the biosensor, depending on the target viruses. The nanocarrier is designed using pH-sensitive polymeric nanoparticle-laden nanocarriers (PNLNs) prepared by sequential nanoprecipitation. The nanoprecipitation of two chromogens, phenolphthalein (PP) and thymolphthalein (TP), is investigated in three different solvent systems in which PNLNs demonstrate a high loading of the chromogen up to 59.75% in dimethylformamide (DMF)/dimethyl sulfoxide (DMSO)/ethanol attributing to the coprecipitation degree of the chromogens and the polymer. The PP-encapsulated PNLNs (PP@PNLNs) and TP-encapsulated PNLNs (TP@PNLNs) are conjugated to antibodies specific to target viruses, influenza virus A subtype H1N1 (IV/A/H1N1) and H3N2 (IV/A/H3N2), respectively. After the addition of anti-IV/A antibody-conjugated magnetic nanoparticles (MNPs) and magnetic separation, the enriched PNLNs/virus/MNPs sandwich structure is treated in an alkaline solution. It demonstrates a synergy reaction in which the degradation of the polymeric boundary and the pH-induced colorimetric development of the chromogen occurred. The derivative binary biosensor shows feasible detection on IV/A with excellent specificities of PP@PNLNs on IV/A/H1N1 and TP@PNLNs on IV/A/H3N2 with LODs of 27.56 and 28.38 fg mL-1, respectively. It intrigues the distinguished analytical signal in human serum with a variance coefficient of 25.8% and a recovery of 93.6-110.6% for one-step subtype influenza virus detection.

Rapid differential detection of subtype H1 and H3 swine influenza viruses using a TaqMan-MGB-based duplex one-step real-time RT-PCR assay.

Swine influenza is an economically important respiratory disease in swine, but it also constantly poses a threat to human health. Therefore, developing rapid, sensitive, and efficient detection methods for swine influenza virus (SIV) is important. By aligning the haemagglutinin (HA) gene sequences of SIVs circulating in China over a 10-year period, an H1 primer-probe set targeting both Eurasian avian-like H1N1 (EA H1N1) and pandemic 2009 H1N1 ((H1N1)pdm09) lineages plus a H3 primer-probe set targeting the prevalent human-like H3N2 (HL H3N2) subtype were designed. Subsequently, a TaqMan-MGB-based duplex one-step real-time RT-PCR (RT-qPCR) assay was established and evaluated. The duplex RT-qPCR has a detection limit of 5 copies/µL of HA plasmid for EA H1N1, (H1N1)pdm09, and HL H3N2 subtype SIVs, and its overall detection sensitivity of 100% and specificity of 91.67% matches that of traditional virus isolation through chicken embryo inoculation using experimentally infected mouse lung samples. The method showed high repeatability both within run and between runs, and there was no cross-reactivity against several other porcine viruses that are commonly circulating in China. Furthermore, the duplex RT-qPCR method revealed a higher prevalence of subtype H1 than subtype H3 in 166 nasal swabs from pigs collected from one slaughterhouse between October and December 2019. This assay could be very helpful in the rapid differential detection and routine surveillance of EA H1N1, (H1N1)pdm09, and HL H3N2 SIVs in China.

Molecular Detection of Influenza A and B Viruses in Four Consecutive Influenza Seasons 2015-16 to 2018-19 in a Tertiary Center in Western Saudi Arabia.

INTRODUCTION: Influenza infection poses a significant public health threat. The core for disease prevention and control relies on strengthened surveillance activities, particularly in Saudi Arabia, the country that hosts the largest annual mass gathering event worldwide. This study aimed to assess the molecular and seasonal pattern of influenza virus subtypes in western Saudi Arabia to inform policy decisions on influenza vaccine. METHODS: This cross-sectional study was conducted at King Abdulaziz Medical City, western Saudi Arabia. Medical records and surveillance database of laboratory-confirmed influenza cases were reviewed from October 2015 to 2019. A panel of real-time polymerase chain reactions was performed to detect influenza A and B. Extracted RNA from a subset of positive samples was used to determine influenza A subtypes and influenza B lineages. RESULTS: This study included a total of 1928 patients with laboratory-confirmed influenza infections. Influenza peaks were observed in October each season, with variant predominant strains. Influenza virus subtypes co-circulate with no reports of co-infection. Influenza A(H3N2) was reported in 42% of the cases, then influenza B (30.7%) and influenza A(H1N1)pdm09 (27.3%). Healthcare workers represented 9.4% of the cases. One-third of the cases (30.4%) were admitted to the hospital with a median admission duration of 4 days. The influenza B viruses were subtyped in 218 cases. Victoria lineage was predominant (64.1%) in 2015 and 2016; however, Yamagata was predominant in the next two consecutive seasons (94.4% and 85.4%, respectively). CONCLUSION: The burden due to influenza B may be underestimated with an observed vaccine mismatch. A quadrivalent influenza vaccine is recommended to reduce the health impact associated with influenza B infections. Molecular surveillance of the influenza viruses should be enhanced continuously for a better understanding of the influenza activity and assessment of vaccine effectiveness.

Respiratory microbes detected in hospitalized adults with acute respiratory infections: associations between influenza A(H1N1)pdm09 virus and intensive care unit admission or fatal outcome in Vietnam (2015-2017).

BACKGROUND: Acute respiratory tract infection (ARI) is a leading cause of hospitalization, morbidity, and mortality worldwide. Respiratory microbes that were simultaneously detected in the respiratory tracts of hospitalized adult ARI patients were investigated. Associations between influenza A(H1N1)pdm09 virus (H1N1pdm) detection and intensive care unit (ICU) admission or fatal outcome were determined. METHODS: This prospective observational study was conducted between September 2015 and June 2017 at Bach Mai Hospital, Hanoi, Vietnam. Inclusion criteria were hospitalized patients aged ≥15 years; one or more of symptoms including shortness of breath, sore throat, runny nose, headache, and muscle pain/arthralgia in addition to cough and fever > 37.5 °C; and ≤ 10 days from the onset of symptoms. Twenty-two viruses, 11 bacteria, and one fungus in airway specimens were examined using a commercial multiplex real-time PCR assay. Associations between H1N1pdm detection and ICU admission or fatal outcome were investigated by univariate and multivariate logistic regression analyses. RESULTS: The total of 269 patients (57.6% male; median age, 51 years) included 69 ICU patients. One or more microbes were detected in the airways of 214 patients (79.6%). Single and multiple microbes were detected in 41.3 and 38.3% of patients, respectively. Influenza A(H3N2) virus was the most frequently detected (35 cases; 13.0%), followed by H1N1pdm (29 cases; 10.8%). Hematological disease was associated with ICU admission (p < 0.001) and fatal outcomes (p < 0.001) using the corrected significance level (p = 0.0033). Sex, age, duration from onset to sampling, or number of detected microbes were not significantly associated with ICU admission or fatal outcomes. H1N1pdm detection was associated with ICU admission (odds ratio [OR] 3.911; 95% confidence interval [CI] 1.671-9.154) and fatal outcome (OR 5.496; 95% CI 1.814-16.653) after adjusting for the confounding factors of comorbidities, bacteria/Pneumocystis jirovecii co-detection, and age. CONCLUSIONS: H1N1pdm was associated with severe morbidity and death in adult patients hospitalized with respiratory symptoms. The diagnosis of subtype of influenza virus may be epidemiologically important.

Epidemiology of Influenza in Fars Province, Southern Iran; a Population-Based Study (2015-2019).

BACKGROUND: Influenza is one of the most important viral diseases with high mortality and morbidity that can have a great impact on public health and economy. OBJECTIVE: To investigate the clinical and epidemiological features of influenza virus A/H1N1, A/H3N2, and B infection in Fars province, southern Iran, in 2015-2019. METHODS: In this retrospective cross-sectional study, we assessed the archived data of Syndromic Surveillance System of Iran's Health Ministry, allowed access by Communicable Diseases' Unit of Health chancellor of Shiraz University of Medical Sciences, from December 22, 2015 to September 22, 2019. The participants included all patients whose data were recorded as influenza-like illness (ILI) and severe acute respiratory infections/illness (SARI). Influenza viral infection was confirmed by reverse-transcriptase polymerase chain reaction (RT-PCR). RESULTS: Totally, 1269 patients suspected of influenza were sampled. The mean ± SD of age was 29.40 ± 26.91 years. Fever was the most common symptom (68.6%). The highest incidence was in winter (55.9%). Of 928/1269 laboratory's results which were recorded in the registry, 204 (16.08%) samples were positive and 724 (57.05%) were negative. Among 204 positive results, 191 (15.05%) were influenza type A, and 8 (0.63%) influenza type B. Among patients with definite influenza type A, 34 (2.68%) had H1N1/p subtype, 58 (4.57%) H3N2, and one (0.08%) had other subtypes; however, subtypes were not identified in 7.72% of patients. Six (3.0%) patients with confirmed influenza expired. CONCLUSION: The incidence of influenza, especially type A, in Fars province, southern Iran is considerable and requires more attention for prevention in health policy programs.

Inference of population genetic parameters from an irregular time series of seasonal influenza virus sequences.

Basic summary statistics that quantify the population genetic structure of influenza virus are important for understanding and inferring the evolutionary and epidemiological processes. However, the sampling dates of global virus sequences in the last several decades are scattered nonuniformly throughout the calendar. Such temporal structure of samples and the small effective size of viral population hampers the use of conventional methods to calculate summary statistics. Here, we define statistics that overcome this problem by correcting for the sampling-time difference in quantifying a pairwise sequence difference. A simple linear regression method jointly estimates the mutation rate and the level of sequence polymorphism, thus providing an estimate of the effective population size. It also leads to the definition of Wright's FST for arbitrary time-series data. Furthermore, as an alternative to Tajima's D statistic or the site-frequency spectrum, a mismatch distribution corrected for sampling-time differences can be obtained and compared between actual and simulated data. Application of these methods to seasonal influenza A/H3N2 viruses sampled between 1980 and 2017 and sequences simulated under the model of recurrent positive selection with metapopulation dynamics allowed us to estimate the synonymous mutation rate and find parameter values for selection and demographic structure that fit the observation. We found that the mutation rates of HA and PB1 segments before 2007 were particularly high and that including recurrent positive selection in our model was essential for the genealogical structure of the HA segment. Methods developed here can be generally applied to population genetic inferences using serially sampled genetic data.

[Peculiarities of the influenza and ARVI viruses circulation during epidemic season 2019-2020 in some regions of Russia].

INTRODUCTION: The surveillance of influenza viruses in ARVI structure and study of their properties in epidemic season 2019-2020 in Russian Federation are actual for investigations due to tasks of Global Influenza Strategy initiated by WHO in 2019. MATERIAL AND METHODS: The data of epidemiological surveillance on influenza- and ARVI-associated morbidity and hospitalization in different age groups of population were analyzed; virological, genetic and statistical methods were used. RESULTS: Preschool children were involved in epidemic the most. Meanwhile, the highest rate of hospitalization was observed in patients of 18-40 years old. Influenza A(H1N1)pdm09 virus dominated in etiology of ARVI in hospitalized patients and pneumonia. The role of respiratory viruses in severe cases of pneumonia and bronchoalveolar syndrome in children was shown. The differences in spectrum of circulating viruses caused ARVI in different regions of Russia were found. Influenza A(H1N1)pdm09 and B/Victoria-like viruses were the main etiological agents that caused of epidemic; its activity among all ARVI was 7.3 and 8.0%, respectively. The differences in antigenic properties of influenza A(H3N2) and B epidemic strains compared to vaccine viruses were found. The populations of epidemic strains were presented by following dominant genetic groups: 6B1.A5/183P for A(H1N1)pdm09, 3С.2а1b+137F for A(H3N2) and V1A.3 line B/Victoria-like for B viruses. The good profile of epidemic strains susceptibility to anti-neuraminidase inhibitors has been saved. The most of the studied influenza strains had the receptor specificity characteristic of human influenza viruses. CONCLUSIONS: Obtained results identified the peculiarities of viruses caused the influenza and ARVI in epidemic season 2019-2020 in different regions of Russia. These results suggested the important role of influenza A(H1N1) pdm09 in severe cases and pneumonia in adults 18-40 years old. The continuing drift in influenza viruses was found, which, apparently, could not but affect the efficacy of vaccine prophylaxis and was also considered in the recommendations of WHO experts on the composition of influenza vaccines for the countries of the Northern Hemisphere in the 2020-2021 season.

A universal RT-qPCR assay for "One Health" detection of influenza A viruses.

The mutual dependence of human and animal health is central to the One Health initiative as an integrated strategy for infectious disease control and management. A crucial element of the One Health includes preparation and response to influenza A virus (IAV) threats at the human-animal interface. The IAVs are characterized by extensive genetic variability, they circulate among different hosts and can establish host-specific lineages. The four main hosts are: avian, swine, human and equine, with occasional transmission to other mammalian species. The host diversity is mirrored in the range of the RT-qPCR assays for IAV detection. Different assays are recommended by the responsible health authorities for generic IAV detection in birds, swine or humans. In order to unify IAV monitoring in different hosts and apply the One Health approach, we developed a single RT-qPCR assay for universal detection of all IAVs of all subtypes, species origin and global distribution. The assay design was centred on a highly conserved region of the IAV matrix protein (MP)-segment identified by a comprehensive analysis of 99,353 sequences. The reaction parameters were effectively optimised with efficiency of 93-97% and LOD95% of approximately ten IAV templates per reaction. The assay showed high repeatability, reproducibility and robustness. The extensive in silico evaluation demonstrated high inclusivity, i.e. perfect sequence match in the primers and probe binding regions, established as 94.6% for swine, 98.2% for avian and 100% for human H3N2, pandemic H1N1, as well as other IAV strains, resulting in an overall predicted detection rate of 99% on the analysed dataset. The theoretical predictions were confirmed and extensively validated by collaboration between six veterinary or human diagnostic laboratories on a total of 1970 specimens, of which 1455 were clinical and included a diverse panel of IAV strains.

Canine and Feline Influenza.

Influenza virus infections of carnivores-primarily in dogs and in large and small cats-have been repeatedly observed to be caused by a number of direct spillovers of avian viruses or in infections by human or swine viruses. In addition, there have also been prolonged epizootics of an H3N8 equine influenza virus in dogs starting around 1999, of an H3N2 avian influenza virus in domestic dog populations in Asia and in the United States that started around 2004, and an outbreak of an avian H7N2 influenza virus among cats in an animal shelter in the United States in 2016. The impact of influenza viruses in domesticated companion animals and their zoonotic or panzootic potential poses significant questions for veterinary and human health.

Implementing an Influenza Vaccine Effectiveness Study in a Hospital Context in Portugal: The EVA Hospital Project.

INTRODUCTION: The project 'Integrated Monitoring of Vaccines in Europe' aimed to measure seasonal influenza vaccine effectiveness against hospitalised adults, aged 65 years and over, with influenza. We describe the protocol implementation in Portugal. MATERIAL AND METHODS: We implemented a test-negative design, targeting community-dwelling patients aged 65 years old and over hospitalised with severe acute respiratory illness. Patients were reverse transverse-polymerase chain reaction tested for influenza. Cases were those positive for influenza while others were controls. Most variables were collected using hospital medical records. Selection bias was evaluated by comparison with the laboratory influenza test requests database according to demographic characteristics. Crude, season-adjusted influenza vaccine effectiveness was estimated as = 1 - odds ratio, and 95% confidence intervals were obtained by conditional logistical regression, matched with the disease onset month. RESULTS: The recruitment rate was 37.8%. Most participants (n = 368) were female (55.8%) and aged 80 years old and over (55.8%). This was similar to values for potentially eligible severe acute respiratory illness patients (80 years old and over: 56.8%, female: 56.2%). The proportion of missing values was below 2.5% for 20 variables and above 5% (maximum 11.6%) for six variables. Influenza vaccine effectiveness estimates were 62.1% against AH1pdm09 (95% confidence intervals: -28.1 to 88.8), 14.9% against A(H3N2) (95% confidence intervals: -69.6 to 57.3), 43.6% against B/Yam (95% confidence intervals: -66.2 to 80.8). DISCUSSION: Given the non-existence of a coded admission database in either participating hospital the selection of severe acute respiratory illness due to clinical features was the feasible one. These results are only valid for the older adult population residing in the catchment area of the two participating hospitals who were admitted to a public hospital with severe influenza or SARI symptoms. CONCLUSION: Despite the low participation rate, we observed comparable characteristics of participants and eligible severe acute respiratory illness patients. Data quality was high, and influenza vaccine effectiveness results were in accordance with the results of meta-analyses and European season-specific estimates. The final sample size was low, which inhibited obtaining estimates with good precision.

Introdução: O projeto "Integrated Monitoring of Vaccines in Europe" pretende medir a efetividade da vacina antigripal nas hospitalizações por gripe nos adultos com mais de 65 anos. Este estudo pretende descrever a implementação do protocolo em Portugal. Material e Métodos: Implementou-se um estudo com desenho caso-controlo teste negativo. A população-alvo foram indivíduos com idade superior a 65 anos, hospitalizados com doença respiratória aguda grave. Os doentes foram testados para gripe por reverse transverse-polimerase chain reaction. Foram considerados casos aqueles com resultado positivo; os restantes foram controlos. Os dados foram obtidos através de registo clinicos. O potencial viés de seleção foi avaliado por comparação de características demográficas e enfermarias com dados das requisições laboratoriais. A efetividade da vacina, foi estimada em 1 ­ odds ratio por regressão logística condicional, emparelhada para o mês de início da doença. Resultados: A taxa de recrutamento foi de 37,8%. A maioria dos participantes (n = 368) era do sexo feminino (55,8%) e tinha idade superior a 80 anos (55,8%). Padrão similar foi verificado nos doentes elegíveis (idade superior a 80 anos: 56,8%; feminino: 56,2%). Os valores omissos foram inferiores a 2,5% em 20 variáveis e acima de 5% (máximo 11,6%) em seis variáveis. As estimativas da efetividade foram 62,1% contra AH1pdm09 (intervalo de confiança IC 95%: -28,1, 88,8); 14,9% contra A (H3) (intervalo de confiança 95%: -69,6; 57,3) e 43,6% contra B/yamagata (intervalo de confiança 95%: -66,2; 80,8). Discussão: Dada a inexistência de uma codificação em base de dados de admissão em qualquer um dos hospitais participantes, a abordagem de identificação e casos clínicos de doença respiratória aguda grave foi a exequível. Estes resultados são válidos para a população idosa residente na área de abrangência dos dois hospitais participantes que foram internados em um hospital público com gripe grave ou sintomas de doença respiratória aguda grave. Conclusão: Apesar da baixa taxa de participação, observámos características comparáveis entre os participantes e os doentes elegíveis. A qualidade dos dados foi elevada, e os resultados da efetividade concordantes com resultados de meta-análises e estimativas europeias. A reduzida dimensão da amostra impediu a obtenção de estimativas mais precisas.

Self-assembled chromogen-loaded polymeric cocoon for respiratory virus detection.

Inspired by the self-assembly approach, in this work, the chromogen, 3,3',5,5'-tetramethylbenzidine (TMB), was successfully co-precipitated in aqueous solution to form collective nanoparticles (NPs) of signal molecules (TMB-NPs). Utilizing poly(lactide-co-glycolide) (PLGA) in the molecular delivery approach, the formed emulsion nanovesicle (TMB-NPs@PLGA) exhibits an enrichment of the collective signal molecules in a single antibody-antigen conjugation. A specific antibody-conjugated TMB-NPs@PLGA forms an immunocomplex sandwich structure upon the addition of influenza virus (IV)/A. The addition of dimethyl sulfoxide (DMSO) dissolves the PLGA nanovesicles, releasing the encapsulated TMB-NPs. Sequentially, the TMB-NPs release TMB molecules upon the addition of DMSO. The released TMB is catalytically oxidized by H2O2 with self-assembled protein-inorganic nanoflowers, where copper nanoflowers (CuNFs) acted as the nanozyme. The developed immunoassay demonstrates high sensitivity for IV/A with a limit of detection (LOD) as low as 32.37 fg mL-1 and 54.97 fg mL-1 in buffer and serum, respectively. For practical needs, a clinically isolated IV/A/H3N2 and spike protein of SARS-CoV-2 were detected with the LODs of 17 pfu mL-1 and 143 fg mL-1, respectively. These results show the applicability of the advanced TMB-NPs@PLGA-based colorimetric sensor for the highly sensitive detection of airborne respiratory viruses.