Spatial and temporal distribution characteristics of seasonal A(H3N2) influenza in China, 2014-2019 / 中华流行病学杂志

Objective: To analyze the spatial and temporal distribution characteristics of seasonal A(H3N2) influenza [influenza A(H3N2)] in China and to provide a reference for scientific prevention and control. Methods: The influenza A(H3N2) surveillance data in 2014-2019 was derived from China Influenza Surveillance Information System. A line chart described the epidemic trend analyzed and plotted. Spatial autocorrelation analysis was conducted using ArcGIS 10.7, and spatiotemporal scanning analysis was conducted using SaTScan 10.1. Results: A total of 2 603 209 influenza-like case sample specimens were detected from March 31, 2014, to March 31, 2019, and the influenza A(H3N2) positive rate was 5.96%(155 259/2 603 209). The positive rate of influenza A(H3N2) was statistically significant in the north and southern provinces in each surveillance year (all P<0.05). The high incidence seasons of influenza A (H3N2) were in winter in northern provinces and summer or winter in southern provinces. Influenza A (H3N2) clustered in 31 provinces in 2014-2015 and 2016-2017. High-high clusters were distributed in eight provinces, including Beijing, Tianjin, Hebei, Shandong, Shanxi, Henan, Shaanxi, and Ningxia Hui Autonomous Region in 2014-2015, and high-high clusters were distributed in five provinces including Shanxi, Shandong, Henan, Anhui, and Shanghai in 2016-2017. Spatiotemporal scanning analysis from 2014 to 2019 showed that Shandong and its surrounding twelve provinces clustered from November 2016 to February 2017 (RR=3.59, LLR=9 875.74, P<0.001). Conclusion: Influenza A (H3N2) has high incidence seasons with northern provinces in winter and southern provinces in summer or winter and obvious spatial and temporal clustering characteristics in China from 2014-2019.

A broadly neutralizing human monoclonal antibody against the hemagglutinin of avian influenza virus H7N9 / 中华医学杂志(英文版)

BACKGROUND@#The new emerging avian influenza A H7N9 virus, causing severe human infection with a mortality rate of around 41%. This study aims to provide a novel treatment option for the prevention and control of H7N9.@*METHODS@#H7 hemagglutinin (HA)-specific B cells were isolated from peripheral blood plasma cells of the patients previously infected by H7N9 in Jiangsu Province, China. The human monoclonal antibodies (mAbs) were generated by amplification and cloning of these HA-specific B cells. First, all human mAbs were screened for binding activity by enzyme-linked immunosorbent assay. Then, those mAbs, exhibiting potent affinity to recognize H7 HAs were further evaluated by hemagglutination-inhibiting (HAI) and microneutralization in vitro assays. Finally, the lead mAb candidate was selected and tested against the lethal challenge of the H7N9 virus using murine models.@*RESULTS@#The mAb 6-137 was able to recognize a panel of H7 HAs with high affinity but not HA of other subtypes, including H1N1 and H3N2. The mAb 6-137 can efficiently inhibit the HA activity in the inactivated H7N9 virus and neutralize 100 tissue culture infectious dose 50 (TCID50) of H7N9 virus (influenza A/Nanjing/1/2013) in vitro, with neutralizing activity as low as 78 ng/mL. In addition, the mAb 6-137 protected the mice against the lethal challenge of H7N9 prophylactically and therapeutically.@*CONCLUSION@#The mAb 6-137 could be an effective antibody as a prophylactic or therapeutic biological treatment for the H7N9 exposure or infection.

Mudança no padrão de vírus respiratórios identificados em uma população pediátrica hospitalizada durante os anos de 2019 e 2020 / Change in the pattern of respiratory viruses identified in a pediatric population hospitalized during the years of 2019 and 2020

Introdução: de destaque como agente etiológico em várias doenças respiratórias, os vírus, tem grande importância dentro da Pneumologia Pediátrica. Objetivo: estudar os vírus identificados de secreções respiratórias de pacientes pediátricos, hospitalizados na enfermaria e UTI pediátrica, durante o período de janeiro de 2019 a dezembro de 2020. Metodologia: levantamento de resultados do RT-PCR (reação da transcriptase reversa seguida pela reação em cadeia da polimerase) de secreções respiratórias de pacientes pediátricos, através do GAL (Gerenciamento de Análises Laboratoriais) aplicando os filtros necessários para selecionar os pacientes da instituição e o período estipulado. Resultados: Foram realizadas 30 coletas em 2019 e 196 em 2020 de secreções respiratórias devido ao quadro de Síndrome Respiratória. As amostras coletadas em 2019 foram positivas para vírus em 56,7% dos casos investigados, sendo 6,7% para Influenza e 50% para Vírus Sincicial Respiratório (VSR), enquanto que em 2020 as amostras foram positivas em 21,4% dos casos, sendo todos eles para SARS-CoV-2. O período do ano com maior número de coletas de secreção foi em maio e junho considerando o ano de 2019 (60% das coletas de 2019), e julho, agosto e dezembro considerando o ano de 2020 (42,8% das coletas de 2020), com uma positividade de 77,7% (2019) e 25% (2020) para os vírus solicitados para pesquisa. Conclusão: Pôde-se perceber uma importante mudança no perfil dos vírus identificados dos quadros respiratórios entre 2019 e 2020, comparáveis ao perfil apresentado pelos Boletins Epidemiológicos do Ministério da Saúde, principalmente no ano de 2020 com o surgimento do novo coronavírus e sua pandemia. A etiologia viral presente na grande maioria dos quadros respiratórios da pediatria, deve sempre ser valorizada e os testes de identificação viral são ferramentas de grande aplicabilidade na clínica.

Introduction: highlighted as an etiological agent in several respiratory diseases, viruses, has great importance in Pediatric Pulmonology. Objective: study the viruses identified from respiratory secretions of pediatric patients hospitalized in the pediatric ward and ICU, during the period from January 2019 to December 2020. Methodology: survey of results of the RT-PCR (reverse transcriptase reaction followed by polymerase chain reaction) of respiratory secretions of pediatric patients, through the LAM (Laboratory Analysis Management) applying the necessary filters to select the patients of the institution and the stipulated period. Results: Thirty collections were performed in 2019 and 196 in 2020 for respiratory secretions due to the Respiratory Syndrome. The samples collected in 2019 were positive for viruses in 56.7% of the investigated cases, with 6.7% for Influenza and 50% for Respiratory Syncytial Virus (RSV), while in 2020 the samples were positive in 21.4% of the cases, all of which were for SARS-Cov-2. The period of the year with the highest number of secretion collections was in May and June considering 2019 (60% of 2019 collections), and July, August and December considering 2020 (42.8% of 2020 collections), with a positivity of 77.7% (2019) and 25% (2020) for viruses requested for research. Conclusion: It was possible to notice an important change in the profile of the viruses identified in respiratory conditions between 2019 and 2020, comparable to the profile presented by the Epidemiological Bulletins of the Ministry of Health, especially in the year 2020 with the emergence of the new coronavirus and its pandemic. The viral etiology present in the vast majority of pediatric respiratory conditions should always be valued and viral identification tests are tools of great applicability in the clinic.

Características clínicas de pacientes pediátricos internados por Influenza A: comparación de dos subtipos virales (H1N1) y (H3N2) / Clinical characteristics of pediatric patients hospitalized due to Influenza A: comparison of two viral subtypes (H1N1 and H3N2)

Influenza is a respiratory disease ocasionated by influenza virus A and B. Is a disease with high morbi-mortality world-wide. Influenza produces an acute febrile respiratory illness with cough, headache and myalgias for 3-4 days, with simptoms that may persist for as long as 2 weeks. There are three types of influenza virsuses: A, B and C, of whom the type a has a higher ability to originate pandemias and is subclassified according to their surface antigens: hemaglutinine (H) and neuraminidase (N). Of the capacity of mutation that has the influenza virus and the consequent expression of different proteins, can modify its virulence. The transmission route is through direct contact with secretetory repirations. The transmission route is through direct contact with secretetory repirations. The incubation period is scant, between 12-72 hs. The aim of this study was to compare the clinical characteristics demographicals and evolutive of pediatric patients hospitalized because by Influenze A: subtypes H1N1 (pdm2009) and H3N2. An observative study was performed, retrospective, using data of hospitalizations of children during the years 2016 and 2017 with influenza A confirmed by laboratory. The study also, aimed to evaluate if the viral subtype constitutes a factor of risk, independent for complicated hospitalization (admission to intensive care and/or development of complications) in hospitalized children. The results obtained in the study are detailed in the paper. In conclusion, both viral subtypes affected mainly to children with risk factors. The viral subtype H1N1 was related with higher severety in hospitalized children. is of most importance to perform preventive works, specially in vulnerable groups, offering a good cover of immunizations. The clinical parameters arae commented (AU)

Intranasal Immunization Using CTA1-DD as a Mucosal Adjuvant for an Inactivated Influenza Vaccine / 生物医学与环境科学（英文）

OBJECTIVE@#To evaluate the effect of intranasal immunization with CTA1-DD as mucosal adjuvant combined with H3N2 split vaccine.@*METHODS@#Mice were immunized intranasally with PBS (negative control), or H3N2 split vaccine (3 μg/mouse) alone, or CTA1-DD (5 μg/mouse) alone, or H3N2 split vaccine (3 μg/mouse) plus CTA1-DD (5 μg/mouse). Positive control mice were immunized intramuscularly with H3N2 split vaccine (3 μg/mouse) and alum adjuvant. All the mice were immunized twice, two weeks apart. Then sera and mucosal lavages were collected. The specific HI titers, IgM, IgG, IgA, and IgG subtypes were examined by ELISA. IFN-γ and IL-4 were test by ELISpot. In addition, two weeks after the last immunization, surivival after H3N2 virus lethal challenge was measured.@*RESULTS@#H3N2 split vaccine formulated with CTA1-DD could elicit higher IgM, IgG and hemagglutination inhibition titers in sera. Furthermore, using CTA1-DD as adjuvant significantly improved mucosal secretory IgA titers in bronchoalveolar lavages and vaginal lavages. Meanwhile this mucosal adjuvant could enhance Th-1-type responses and induce protective hemagglutination inhibition titers. Notably, the addition of CTA1-DD to split vaccine provided 100% protection against lethal infection by the H3N2 virus.@*CONCLUSION@#CTA1-DD could promote mucosal, humoral and cell-mediated immune responses, which supports the further development of CTA1-DD as a mucosal adjuvant for mucosal vaccines.

Influenza cases increase in recent weeks

The seasonal influenza [flu] viruses are detected year-round, however influenza activity, in the northern hemisphere, often begins to increase by the end of autumn. During the winter months, influ-enza may infect up to one fifth of the population and cause substantial mortality.

Cambios en la presentación clínica de la influenza A H1N1pdm09 después de la pandemia / Changes in the clinical presentation of Influenza A H1N1pdm09 after the pandemic

Background: After the 2009 influenza pandemic the H1N1pdm09 strain circulate seasonally. In 2015, Puerto Montt Hospital in Chile faced a simultaneous outbreak of both seasonal H3N2 and H1N1pdm09 influenza A (IA). Aim: To evaluate the clinical differences between the two viral strains and recent changes in the behavior of H1N1pdm09 IA. Material and Methods: We set up a retrospective study including every adult hospitalized in Puerto Montt Hospital in 2015 due to IA, confirmed by reverse transcription polymerase chain reaction. We compared epidemiological data, clinical presentation, complications, and the outcome of patients with H1N1pdm09 versus those with seasonal influenza. In parallel, we compared 62 cases of thatH1N1 IA from 2015 with 100 cases who were hospitalized and analyzed in 2009. Results: Between July and October 2015, 119 adults with confirmed IA were hospitalized. From 2009 to 2015, the mean age of patients with IAH1N1pdm09 increased from 40.4 ± 17 to 58.8 ± 16 years (p < 0.01). Pneumonia as the cause of hospitalization decreased from 75 to 58% of patients, (p = 0.04). Likewise, the presence of comorbidities increased from 53 to 74%, (p < 0.01). Compared with seasonal H3N2, patients with IAH1N1pdm09 IA were more likely to require intensive care (p < 0.01) and mechanical ventilation (p < 0.01) and developed septic shock (p = 0.03). Their mortality was non-significantly higher (13 and 5% respectively). Conclusions: The clinical presentation of H1N1pdm09 IA has varied over time and now affects an older population, with a greater number of comorbidities. It also appears to be adopting the clinical behavior of a classic seasonal influenza virus.

Detección de virus influenza A, B y subtipos a (H1N1) pdm09, A (H3N2) por múltiple rt-pcr en muestras clínicas / Detection of influenza A, B and subtypes A (H1N1) pdm09, A (H3N2) viruses by multiple qrt-pcr in clinical samples

RESUMEN Objetivos. Estandarizar la técnica de reacción en cadena de la polimerasa en tiempo real (RT-PCR) múltiple para la detección de virus influenza A, B y tipificación de subtipos A (H1N1) pdm09, A (H3N2) en muestras clínicas. Materiales y métodos. Se analizaron 300 muestras de hisopado nasofaríngeo. Esta metodología fue estandarizada en dos pasos: la primera reacción detectó el gen de la matriz del virus de influenza A, gen de la nucleoproteína del virus influenza B y el gen GAPDH de las células huésped. La segunda reacción detectó el gen de la hemaglutinina de los subtipos A (H1N1) pandémico (pdm09) y A (H3N2). Resultados. Se identificaron 109 muestras positivas a influenza A y B, de las cuales 72 fueron positivas a influenza A (36 positivas a influenza A (H1N1) pdm09 y 36 positivos a influenza A (H3N2)) y 37 muestras positivas a influenza B. 191 fueron negativas a ambos virus mediante RT-PCR en tiempo real multiplex. Se encontró una sensibilidad y especificidad del 100% al analizar los resultados de ambas reacciones. El límite de detección viral fue del rango de 7 a 9 copias/µL por virus. Los resultados no mostraron ninguna reacción cruzada con otros virus tales como adenovirus, virus sincitial respiratorio, parainfluenza (1,2 y 3), metapneumovirus, subtipos A (H1N1) estacional, A (H5N2) y VIH. Conclusiones. La RT-PCR múltiple demostró ser una prueba muy sensible y específica para la detección de virus influenza A, B y subtipos A (H1N1, H3N2) y su uso puede ser conveniente en brotes estacionales.

ABSTRACT Objectives. To describe the clinical and epidemiological characteristics of patients diagnosed with epidermolysis bullosa (EB) at the Instituto Nacional de Salud (INSN) in Lima, Peru; a National Reference Center for this disease. Material and methods . Observational, descriptive and transversal study. We reviewed the clinical histories and laboratory tests of patients diagnosed with EB treated in INSN from 1993 to 2015. Results. 93 patients were registered. The average age was 7.9 ± 5.6 years; 53.8% (n = 50) were boys. Clinical forms corresponded to dystrophic EB with 41 (44.1%) cases, simple EB with 39 (41.9%) union EB cases with 8 (8.6%) and Kindler syndrome with 4 (4.3%) cases. The clinical form could not be identified in a case. A total of 48 cases (51.6%) came from Lima and Callao, and 45 cases (48.4%) from other provinces of the country. Extracutaneous manifestations involved gastrointestinal (44.1%), ocular (37.6%), odontogenic (87.1%), and nutritional (79.6%) involvement, as well as pseudosindactilia (16.1%). Chronic malnutrition (71.6%), acute malnutrition (17.6%) and anemia (62.4%) were found. Mortality corresponded to 6 cases (6.5%). Conclusions. 93 cases of EB were reported in INSN, the predominant clinical presentation was the dystrophic form.

Surveillance of antiviral resistance markers in Argentina: detection of E119V neuraminidase mutation in a post-treatment immunocompromised patient

Although vaccines are the best means of protection against influenza, neuraminidase inhibitors are currently the main antiviral treatment available to control severe influenza cases. One of the most frequent substitutions in the neuraminidase (NA) protein of influenza A(H3N2) viruses during or soon after oseltamivir administration is E119V mutation. We describe the emergence of a mixed viral population with the E119E/V mutation in the NA protein sequence in a post-treatment influenza sample collected from an immunocompromised patient in Argentina. This substitution was identified by a real-time reverse transcriptase polymerase chain reaction (RT-PCR) protocol and was confirmed by direct Sanger sequencing of the original sample. In 2014, out of 1140 influenza samples received at the National Influenza Centre, 888 samples (78%) were A(H3N2) strains, 244 (21.3%) were type B strains, and 8 (0.7%) were A(H1N1)pdm09 strains. Out of 888 A(H3N2) samples, 842 were tested for the E119V substitution by quantitative RT-PCR: 841 A(H3N2) samples had the wild-type E119 genotype and in one sample, a mixture of viral E119/ V119 subpopulations was detected. Influenza virus surveillance and antiviral resistance studies can lead to better decisions in health policies and help in medical treatment planning, especially for severe cases and immunocompromised patients.

Influenza in the EMR: low levels of activity

The influenza activity remained low in the Eastern Mediterranean Region [EMR] with predominantly detection and circulation of influenza A virus

Seasonal Influenza in 2016 in the Eastern Mediterranean Region

In the Eastern Mediterranean Region of WHO, seasonal influenza peaked at the end of 2015 and beginning of 2016 and returned to low levels by mid May 2016. In most of the countries, the timing of the season generally corresponded to patterns seen in the previous years

Molecular epidemiology and evolution of A[H1N1] pdm09 and H3N2 viruses in Jordan, 2011-2013

Understanding the genetic evolution of A [H1N1]pdm09 and H3N2 viruses can help better select strains to be included in the annual influenza vaccine. There is little information on their evolution in Jordan so this study investigated the genetic and antigenic variability of A[H1N1]pdm09 and H3N2 viruses in Jordan by performing phylogenetic and genetic analyses of the HA and NA genes of A[H1N1]pdm09 and H3N2 viruses between 2011 and 2013. The full HA and NA genes of 16 H1N1-positive samples obtained in our study and 21 published HA sequences and 20 published NA sequences from Jordanian viruses that were available on online gene databases were analysed. For H3N2, we generated 20 HA and 19 NA sequences and included 19 published HA and NA sequences each in the analysis. Jordanian H1N1 viruses had mutations that are characteristic of antigenic group 6 while H3N2 virus mutations belonged to group 3. No markers of resistance to oseltamivir were detected. The individual mutations are described in detail

Characterization of influenza outbreaks in Lebanon during the 2013/14 and 2014/15 seasons

Despite the significant burden of influenza outbreaks, active disease monitoring has been largely absent in the Middle East, including Lebanon. In this study we characterized influenza virus in 440 nasopharyngeal swabs collected from patients with acute respiratory infections during two influenza seasons in Lebanon. Influenza A[H3N2] was dominant in the 2013/14 season while the A[H1N1]pdm09 and B/Yamagata strains were most prevalent in the 2014/15 season. All tested isolates were susceptible to 4 neuraminidase inhibitors [oseltamivir, zanamivir, peramivir and laninamivir]. Genetic analysis of the haemagglutinin gene revealed multiple introductions of influenza viruses into Lebanon from different geographic sources during each season. Additionally, large data gaps were identified in the Middle East region, as indicated by the lack of current influenza sequences in the database from many countries in the region

H1N1 influenza pandemic of 2009 in the Eastern Mediterranean Region: lessons learnt and future strategy

A novel strain of influenza A virus H1N1 surfaced in Mexico in April 2009 and quickly spread across the globe, turning an epidemic into a pandemic. Within two months, the World Health Organization [WHO] declared an international health emergency and raised the threat bar from level V to level VI, i.e. containment to mitigation. During this time, the WHO Regional Office for the Eastern Mediterranean worked closely with its Member States, other stakeholders and WHO headquarters to manage the situation. This report examines the steps taken as part of this response. Programme documents were reviewed and key personnel interviewed for this study. A hallmark of the response was the establishment of the Strategic Health Operations Centre to bring together experts from different technical backgrounds at regional level. Several lessons were learnt that can provide the basis for standard operating procedures, protocols and guidelines for emergency events in future

Preparation and detection of anti-influenza A virus polymerase basic protein 1 polyclonal antibody / 生物工程学报

Influenza A virus is an enveloped virus that belongs to the Orthomyxoviridae family. It has 8 negative RNA segments that encode 16 viral proteins. The viral polymerase consists of 3 proteins (PB 1, PB2 and PA) which plays an important role in the transcription and replication of the influenza A virus. Polymerase basic protein 1 (PB 1) is a critical member of viral polymerase complex. In order to further study the function of PB1, we need to prepare the PB1 antibody with good quality. Therefore, we amplified PB1 conserved region (nt1648-2265) by PCR and cloned it into pET-30a vector, and transformed into Escherichia coli BL2 1. The expression of His tagged PB 1 protein was induced by IPTG, and His-PB 1 proteins were purified by Ni-NTA resin. For preparation of PB 1 protein antiserum, rabbits were immunized with His-PB 1 fusion protein 3 times. Then the titer of PB 1 polyclonal antibody was measured by indirect ELISA. The antibody was purified by membrane affinity purification and subjected to immunoblotting analysis. Data showed that PB1 antibody can recognize PB 1 protein from WSN virus infected or pCMV FLAG-PB 1 transfected cells. Meanwhile, PB 1 antibody can also recognize specifically other subtype strains of influenza A virus such as H9N2 and H3N2. PB 1 polyclonal antibody we generated will be a useful tool to study the biological function of PB1.

A novel M2e-multiple antigenic peptide providing heterologous protection in mice

Swine influenza viruses (SwIVs) cause considerable morbidity and mortality in domestic pigs, resulting in a significant economic burden. Moreover, pigs have been considered to be a possible mixing vessel in which novel strains loom. Here, we developed and evaluated a novel M2e-multiple antigenic peptide (M2e-MAP) as a supplemental antigen for inactivated H3N2 vaccine to provide cross-protection against two main subtypes of SwIVs, H1N1 and H3N2. The novel tetra-branched MAP was constructed by fusing four copies of M2e to one copy of foreign T helper cell epitopes. A high-yield reassortant H3N2 virus was generated by plasmid based reverse genetics. The efficacy of the novel H3N2 inactivated vaccines with or without M2e-MAP supplementation was evaluated in a mouse model. M2e-MAP conjugated vaccine induced strong antibody responses in mice. Complete protection against the heterologous swine H1N1 virus was observed in mice vaccinated with M2e-MAP combined vaccine. Moreover, this novel peptide confers protection against lethal challenge of A/Puerto Rico/8/34 (H1N1). Taken together, our results suggest the combined immunization of reassortant inactivated H3N2 vaccine and the novel M2e-MAP provided cross-protection against swine and human viruses and may serve as a promising approach for influenza vaccine development.

ARDS in Libya

Recently, some severe cases of acute respiratory disease syndrome [ARDS] were reported from hospitals in Tobruk and Derna cities in Libya. Laboratory test conducted in Libya and re-tested at the National Influenza Centers [NICs] of Egypt and Tunisia detected influenza A [H1N1] pdm09 as the causative agent for these severe respiratory diseases amongst the hospitalized patients. Of the ten cases reported so far [until the end of December] six patients were fatal

Recommended Seasonal Influenza Vaccine for use in 2015-2016

In February 2015, WHO has recommended influenza viruses for inclusion in the seasonal influenza vaccines in the northern hemisphere for 2015-16. These recommendations are based on the antigenic and genetic analysis of the circulating influenza viruses shared by the countries with WHO through the Global Influenza Surveillance and Response System [GISRS]

Susceptibility of human influenza A (H3N2) viruses to neuraminidase inhibitors isolated during 2011-2012 in China / 中华预防医学杂志

<p><b>OBJECTIVE</b>To analyze the susceptibility of influenza A (H3N2) viruses to neuraminidase inhibitors during 2011-2012 in Mainland China.</p><p><b>METHODS</b>All the tested viruses were obtained from the Chinese National Influenza Surveillance Network, which covers 31 provinces in mainland China, including 408 network laboratories and 554 sentinel hospitals. In total 1 903 viruses were selected with isolation date from January 1, 2011 to December 31, 2012 in Mainland China, among these viruses, 721 were confirmed to be influenza A (H3N2) virus by Chinese National Influenza Center and tested for the susceptibility to oseltamivir and zanamivir using chemiluminescence-based assay. The neuraminidase inhibitor sensitive reference virus A/Washington/01/2007 (119E) and oseltamivir resistant virus A/Texas/12/2007 (E119V) were used as control in this study. The t -test was used to compare the difference of NAI susceptibility of viruses isolated from different years.</p><p><b>RESULTS</b>The half maximal inhibitory concentration (IC₅₀) of A/Washington/01/2007 for oseltamivir and zanamivir was (0.10 ± 0.02) and (0.30 ± 0.05) nmol/L, respectively. The IC₅₀ of A/Texas/12/2007 for oseltamivir and zanamivir was (4.27 ± 1.60) and (0.20 ± 0.03) nmol/L, respectively. Among the 721 influenza A (H3N2) viruses, 132 influenza A (H3N2) viruses were isolated in 2011 and 589 influenza A (H3N2) viruses were isolated in 2012. The IC50 for oseltamivir ranged from 0.04 to 0.62 nmol/L for viruses isolated in 2011 and ranged from 0.02 to 0.95 nmol/L for viruses in 2012, and the IC₅₀ of all the viruses tested was within 10-fold IC₅₀ (1.0 nmol/L) of the neuraminidase inhibitor sensitive reference virus A/Washington/01/2007. The IC50 of zanamivir ranged from 0.12 to 0.80 nmol/L for viruses in 2011 and ranged from 0.04 to 0.72 nmol/L for viruses in 2012, and was within 10-fold IC₅₀ (3.0 nmol/L) of the neuraminidase inhibitor sensitive reference virus A/Washington/01/2007.</p><p><b>CONCLUSION</b>The influenza A(H3N2) viruses isolated during 2011-2012 in Mainland China were tested to be sensitive to oseltamivir and zanamivir.</p>