Influenza is an acute respiratory infectious disease caused by influenza virus. Pregnancy is associated with physiologic and immunological changes that may increase the risk for influenza virus infection and influenza-related complications. Influenza vaccination is the most effective way to prevent influenza virus infection. WHO and many countries have classified pregnant women as a priority population for influenza vaccination, however, there are still many challenges for promoting influenza vaccination in pregnant women in China, influenza vaccination coverage in pregnant women remains low and some influenza vaccine package inserts list pregnancy as an absolute contraindication. In this paper, we summarize the research progress in the effects of influenza infection and influenza vaccination during pregnancy both at home and abroad, then discuss the strategies to promote influenza vaccination in pregnancy for the purpose of providing reference for the related research and policy development in China.
Pregnancy ; Female ; Humans ; Pregnant Women ; Influenza, Human/epidemiology* ; Pregnancy Complications, Infectious/epidemiology* ; Influenza Vaccines ; Vaccination ; Orthomyxoviridae

Influenza is an acute respiratory infectious disease caused by the influenza virus, which seriously affects human health. The influenza virus has frequent antigenic drifts that can facilitate escape from pre-existing population immunity and lead to the rapid spread and annual seasonal epidemics. Influenza outbreaks occur in crowded settings, such as schools, kindergartens, and nursing homes. Seasonal influenza epidemics can cause 3-5 million severe cases and 290 000-650 000 respiratory disease-related deaths worldwide every year. Pregnant women, infants, adults 60 years and older, and individuals with comorbidities or underlying medical conditions are at the highest risk of severe illness and death from influenza. Given the ongoing COVID-19 pandemic, some provinces in southern China had a summer peak of influenza. SARS-CoV-2 may co-circulate with influenza and other respiratory viruses in the upcoming winter-spring influenza season. Annual influenza vaccination is an effective way to prevent influenza, reduce influenza-related severe illness and death, and reduce the harm caused by influenza-related diseases and the use of medical resources. The currently approved influenza vaccines in China include trivalent inactivated influenza vaccine (IIV3), quadrivalent inactivated influenza vaccine (IIV4), and trivalent live attenuated influenza vaccine (LAIV3). IIV3 is produced as a split virus vaccine and subunit vaccine; IIV4 is produced as a split virus vaccine; and LAIV3 is a live, attenuated virus vaccine. Except for some jurisdictions in China, the influenza vaccine is a non-immunization program vaccine-voluntarily and self-paid. China CDC has issued 'Technical Guidelines for Seasonal Influenza Vaccination in China' every year from 2018 to 2021. Over the past year, new research evidence has been published at home and abroad. To better guide the prevention and control of influenza and vaccination in China, the National Immunization Advisory Committee (NIAC) Influenza Vaccination Technical Working Group updated and revised the 2021-2022 Technical Guidelines with the latest research progress into the 'Technical Guidelines for Seasonal Influenza Vaccination in China (2022-2023)'. The new version has updated five key areas: (1) new research evidence-especially research conducted in China-has been added, including new estimates of the burden of influenza disease, assessments of influenza vaccine effectiveness and safety, and analyses of the cost-effectiveness of influenza vaccination; (2) policies and measures for influenza prevention and control that were issued by the government over the past year; (3) influenza vaccines approved for marketing in China this year; (4) composition of trivalent and quadrivalent influenza vaccines for the 2022-2023 northern hemisphere influenza season; and (5) recommendations for influenza vaccination during the 2022-2023 influenza season. The 2022-2023 Guidelines recommend that vaccination clinics provide influenza vaccination services to all people aged 6 months and above who are willing to be vaccinated and have no contraindications to the influenza vaccine. For adults ≥ 18 years, co-administration of COVID-19 and inactivated influenza vaccines in separate arms is acceptable regarding immunogenicity and reactogenicity. For people under 18 years old, there should be at least 14 days between influenza vaccination and COVID-19 vaccination. The Guidelines express no preference for influenza vaccine type or manufacturer-any approved, age-appropriate influenza vaccines can be used. To minimize harm from influenza and limit the impact on the effort to prevent and control COVID-19 in China, the Technical Guidelines recommend priority vaccination of the following high-risk groups during the upcoming 2022-2023 influenza season: (1) healthcare workers, including clinical doctors and nurses, public health professionals, and quarantine professionals; (2) volunteers and staff who provide services and support for large events; (3) people living in nursing homes or welfare homes and staff who take care of vulnerable, at-risk individuals; (4) people who work in high population density settings, including teachers and students in kindergartens and primary and secondary schools, and prisoners and prison staff; and (5) people at high risk of influenza, including adults ≥ 60 years of age, children 6-59 months of age, individuals with comorbidities or underlying medical conditions, family members and caregivers of infants under 6 months of age, and pregnant women. Children 6 months to 8 years of age who receive inactivated influenza vaccine for the first time should receive two doses, with an inter-dose interval of 4 or more weeks. Children who previously received the influenza vaccine and anyone 9 years or older need only one dose. LAIV is recommended only for a single dose regardless of the previous influenza vaccination. Vaccination should begin as soon as influenza vaccines become available and preferably should be completed before the onset of the local influenza season. Repeated influenza vaccination during a single influenza season is not recommended. Vaccination clinics should provide immunization services throughout the epidemic season. Pregnant women can receive inactivated influenza vaccine at any stage of pregnancy. These guidelines are intended for use by staff of CDCs, healthcare workers, maternity and child care institutions and immunization clinic staff members who work on influenza control and prevention. The guidelines will be updated periodically as new evidence becomes available.
Adult ; Infant ; Female ; Pregnancy ; Humans ; Adolescent ; Child, Preschool ; Influenza Vaccines ; Influenza, Human/epidemiology* ; Seasons ; Pandemics ; COVID-19 ; COVID-19 Vaccines ; SARS-CoV-2 ; Vaccination ; China/epidemiology* ; Orthomyxoviridae ; Vaccines, Attenuated ; Vaccines, Combined ; Vaccines, Inactivated

Influenza B virus (IBV) is more likely to cause complications than influenza A virus (IAV) and even causes higher disease burden than IAV in a certain season, but IBV has received less attention. In order to analyze the genetic evolution characteristics of the clinical strain IBV (B/Guangxi-Jiangzhou/1352/2018), we constructed genetic evolution trees and analyzed the homology and different amino acids of hemagglutinin and neuraminidase referring to the vaccine strains recommended by World Health Organization (WHO). We found that strain B/Guangxi-Jiangzhou/1352/2018 was free of interlineage reassortment and poorly matched with the vaccine strain B/Colorado/06/2017 of the same year. We also determined the median lethal dose (LD₅₀) and the pathogenicity of strain B/Guangxi-Jiangzhou/1352/2018 in mice. The results showed that the LD₅₀ was 10^5.9 TCID₅₀ (median tissue culture infective dose), the IBV titer in the lungs reached peak 1 d post infection and the mRNA level of the most of inflammatory cytokines in the lungs reached peak 12 h post infection. The alveoli in the lungs were severely damaged and a large number of inflammatory cells were infiltrated post infection. The study demonstrated that the clinical strain IBV (B/Guangxi-Jiangzhou/1352/2018) could infect mice and induce typical lung inflammation. This will facilitate the research on the pathogenesis and transmission mechanism of IBV, and provide an ideal animal model for evaluation of new vaccines, antiviral and anti-inflammatory drug.
Amino Acids/genetics* ; Animals ; Antiviral Agents/pharmacology* ; China ; Cytokines/metabolism* ; Hemagglutinins/metabolism* ; Humans ; Influenza B virus/pathogenicity* ; Influenza, Human/virology* ; Mice ; Neuraminidase/genetics* ; Orthomyxoviridae Infections/virology* ; Phylogeny ; RNA, Messenger/metabolism* ; Virulence/genetics*

Based on Janus kinase 1/2-signal transducer and activator of transcription 1(JAK1/2-STAT1) signaling pathway, this study explored the immune mechanism of Maxing Shigan Decoction in alleviating the lung tissue and colon tissue damage in mice infected with influenza virus. The influenza virus infection was induced in mice by nasal drip of influenza virus. The normal group, model group, oseltamivir group, antiviral granule group, and Maxing Shigan Decoction group were designed. After intragastric administration of corresponding drugs or normal saline for 3 or 7 days, the body mass was measured, and lung index, spleen index, and thymus index were calculated. Based on hematoxylin-eosin(HE) staining, the pathological changes of lung tissue and colon tissue were observed. Enzyme-linked immunosorbent assay(ELISA) was used to detect serum levels of inflammatory factors interleukin-8(IL-8) and interferon-γ(IFN-γ), Western blot and real-time quantitative polymerase chain reaction(RT-qPCR) to determine the protein and mRNA levels of JAK1, JAK2, STAT1, interferon regulatory factor 9(IRF9), and IFN-γ in lung tissue and colon tissue. The results showed that after 3 and 7 days of administration, the body mass, spleen index, and thymus index were lower(P<0.05 or P<0.01), and the lung index was higher(P<0.01) in the model group than in the normal group. Moreover, the model group showed congestion, edema, and infiltration of a large number of lymphocytes and macrophages in the lung tissue, irregular structure of colon mucosa, ulceration and shedding of epithelial cells, and infiltration of a large number of inflammatory cells. The model group had higher levels of serum IFN-γ(P<0.01), higher protein and mRNA expression of JAK1, JAK2, STAT1, IRF9, IFN-γ in lung tissue(P<0.05 or P<0.01), higher level of JAK2 protein in colon tissue(P<0.01), and higher protein and mRNA levels of STAT1 and IRF9(P<0.05 or P<0.01) than the normal group. Compared with the model group, Maxing Shigan Decoction group had high body mass, spleen index, and thymus index(P<0.05 or P<0.01), low lung index(P<0.05 or P<0.01), and significant alleviation of pathological injury in lung and colon. Moreover, lower serum level of IFN-γ(P<0.05 or P<0.01), protein and mRNA levels of JAK1, JAK2, STAT1, IRF9, and IFN-γ in lung tissue(P<0.05 or P<0.01), JAK2 protein level in colon tissue(P<0.01), and protein and mRNA levels of STAT1 and IRF9(P<0.05 or P<0.01) were observed in the Maxing Shigan Decoction group than in the model group. After 3 days of administration, the level of serum IL-8 in the model group was significantly higher than that in the normal group(P<0.01), and the level in the Maxing Shigan Decoction group was significantly reduced(P<0.01). In conclusion, Maxing Shigan Decoction can significantly up-regulate body mass, spleen index, and thymus index, down-regulate lung index, reduce the levels of IL-8 and IFN-γ, and down-regulate protein and mRNA levels of JAK1, JAK2, STAT1, IRF9, and IFN-γ in lung tissue and protein and mRNA levels of JAK2, STAT1, and IRF9 in colon tissue, and alleviate pathological damage of lung tissue and colon tissue. The mechanism is the likelihood that it inhibits the activation of JAK1/2-STAT1 signaling pathway to alleviate the damage to lung and colon tissue damage.
Mice ; Animals ; Humans ; Janus Kinase 1/genetics* ; STAT1 Transcription Factor/genetics* ; Influenza, Human ; Interleukin-8 ; Signal Transduction ; Orthomyxoviridae Infections ; Interferon-gamma ; Lung ; RNA, Messenger ; Orthomyxoviridae ; Colon

Objective: To analyze the epidemiological characteristics, etiology and hemagglutinin (HA) gene characteristics of prevalent strains in Shandong Province from 2021 to 2022. Methods: The sentinel surveillance data of influenza-like illness (ILI) were collected in Shandong Province from 2021 to 2022. ILI specimens were detected with Real-Time PCR and virus isolation to explore the distribution of influenza viruses in different months. Three virus strains of each city were selected for gene sequencing, and the HA phylogenetic analysis was carried out. Results: In the surveillance-year from 2021 to 2022, 528 263 ILI cases were totally reported in 54 sentinel hospitals for influenza surveillance in Shandong Province. ILI visiting ratio (ILI%) was 4.07%, with the largest number in 0-4 age group (45.86%). The highly frequent season for ILI was in winter and spring, with a peak in the 52nd week, 2021 (6.62%). Totally, nucleic acid was detected in 26 754 specimens, with a positive rate of 27.10%, all of which were type B Victoria influenza. The positive rate reached a peak in the 49th week, 2021 (63.78%). A total of 295 outbreaks of ILI had been reported, in which 269 were positive for influenza virus. Most of outbreaks occurred in the primary school, with a peak in December. Gene evolution analysis showed that the HA gene in Shandong possessed high homology, 98.6% to 99.5%, with the recommended vaccine strains in 2020-2023, which was divided into two branches, V1A.3a.1 and V1A.3a.2. Conclusion: In the surveillance-year of 2021-2022, influenza is prevalent in December in Shandong Province, with a single circulating strain type. The positive rate of influenza virus and outbreak are higher than those in the previous surveillance-year. The circulating strain possesses high HA gene homology with those of the WHO vaccine recommended strains. However, the overall immune barrier of influenza virus is weak.
Humans ; Influenza, Human/prevention & control* ; Phylogeny ; Influenza Vaccines ; Orthomyxoviridae ; Seasons ; China/epidemiology* ; Virus Diseases

Isatidis Radix is the dried root of the Isatis indigotica, with pharmacological effects such as heat-clearing and detoxification, cooling blood and pharyngeal relief, antibacterial and anti-inflammatory effects. It is often used clinically to prevent and treat influenza and other diseases. In this paper, relevant domestic and foreign literatures in recent years were summarized, and it was found that Isatidis Radix lignans, indole alkaloids, polysaccharides, etc. were the main active components against influenza virus. Then its pharmacological effects and the mechanism of action were reviewed, providing a basis for in-depth research on the antiviral effect of Isatidis Radix.
Antiviral Agents/pharmacology* ; Drugs, Chinese Herbal ; Isatis ; Orthomyxoviridae ; Plant Roots ; Polysaccharides

Network pharmacology and the mouse model of viral pneumonia caused by influenza virus FM_1 were employed to explore the main active components and the mechanism of Pulsatilla chinensis against the inflammatory injury of influenza virus-induced pneumonia. The components and targets of P. chinensis were searched from TCMSP, and the targets associated with influenza virus-induced pneumonia were searched from GeneCards. The common targets between P. chinensis and influenza virus-induced pneumonia were identified with Venn diagram established in Venny 2.1. The herb-component-disease-target(H-C-D-T) network was constructed by Cytoscape 3.7.2. The above data were imported into STRING for PPI network analysis. Gene Ontology(GO) enrichment and KEGG pathway enrichment were performed with DAVID. BALB/cAnN mice were infected with the influenza virus FM_1 by nasal drip to gene-rate the mouse model of pneumonia. Immunohistochemistry was adopted to the expression profiling of inflammatory cytokines in the lung tissues of mice in the blank group, model group, and P. chinensis group 1, 3, 5, and 7 days after infection. The pathological changes of lung and trachea of mice in blank group, model group, and P. chinensis group were observed with light microscope and scanning electron microscope at all the time points. The network pharmacological analysis indicated that 9 compounds of P. chinensis were screened out, with a total of 57 targets, 22 of which were overlapped with those of influenza virus-induced pneumonia. A total of 112 GO terms(P<0.05) were enriched, including 81 terms of biological processes, 11 terms of cell components, and 20 terms of molecular functions. A total of 53 KEGG signaling pathways(P<0.05) were enriched, including TNF signaling pathway, influenza A signaling pathway, NF-κB signaling pathway, MAPK signaling pathway and other signaling pathways related to influenza/inflammation. In the P. chinensis group, the expression of TNF-α and IL-1 in the lung tissue was down-regulated on the 3 rd day after infection, and that of IL-6 in the lung tissue was down-regulated on the 5 th day after infection. Light microscopy and scanning electron microscopy showed that P. chinensis significantly alleviated the pathological damage of lung and trachea compared with the model group. This study reflects the multi-components, multi-targets, and multi-pathways of P. chinensis against influenza virus-induced pneumonia. P. chinensis may reduce the production of proinflammatory cytokines and mediators and block the pro-inflammatory signaling pathways to alleviate viral pneumonia, which provides reference for future research.
Animals ; Drugs, Chinese Herbal ; Mice ; Network Pharmacology ; Orthomyxoviridae ; Pneumonia/genetics* ; Pulsatilla

Animals ; Betacoronavirus ; Coronavirus Infections ; drug therapy ; Drug Discovery ; Drug Evaluation, Preclinical ; Enzyme Inhibitors ; therapeutic use ; Humans ; Mice ; Molecular Structure ; Orthomyxoviridae Infections ; drug therapy ; Oseltamivir ; therapeutic use ; Oxidoreductases ; antagonists & inhibitors ; Pandemics ; Pneumonia, Viral ; drug therapy ; Pyrimidines ; biosynthesis

Amino Acid Sequence ; Animals ; Cell Culture Techniques ; Cell Line ; Chickens ; Eggs ; Erythrocytes ; Guinea Pigs ; Hand ; Hemagglutination ; Hemagglutinins ; Humans ; Influenza Vaccines ; Influenza, Human ; Neuraminidase ; Orthomyxoviridae ; Ovum ; Sequence Analysis ; Specific Pathogen-Free Organisms

Emerging and re-emerging RNA viruses occasionally cause epidemics and pandemics worldwide, such as the on-going outbreak of the novel coronavirus SARS-CoV-2. Herein, we identified two potent inhibitors of human DHODH, S312 and S416, with favorable drug-likeness and pharmacokinetic profiles, which all showed broad-spectrum antiviral effects against various RNA viruses, including influenza A virus, Zika virus, Ebola virus, and particularly against SARS-CoV-2. Notably, S416 is reported to be the most potent inhibitor so far with an EC of 17 nmol/L and an SI value of 10,505.88 in infected cells. Our results are the first to validate that DHODH is an attractive host target through high antiviral efficacy in vivo and low virus replication in DHODH knock-out cells. This work demonstrates that both S312/S416 and old drugs (Leflunomide/Teriflunomide) with dual actions of antiviral and immuno-regulation may have clinical potentials to cure SARS-CoV-2 or other RNA viruses circulating worldwide, no matter such viruses are mutated or not.
Animals ; Antiviral Agents ; pharmacology ; therapeutic use ; Betacoronavirus ; drug effects ; physiology ; Binding Sites ; drug effects ; Cell Line ; Coronavirus Infections ; drug therapy ; virology ; Crotonates ; pharmacology ; Cytokine Release Syndrome ; drug therapy ; Drug Evaluation, Preclinical ; Gene Knockout Techniques ; Humans ; Influenza A virus ; drug effects ; Leflunomide ; pharmacology ; Mice ; Mice, Inbred BALB C ; Orthomyxoviridae Infections ; drug therapy ; Oseltamivir ; therapeutic use ; Oxidoreductases ; antagonists & inhibitors ; metabolism ; Pandemics ; Pneumonia, Viral ; drug therapy ; virology ; Protein Binding ; drug effects ; Pyrimidines ; biosynthesis ; RNA Viruses ; drug effects ; physiology ; Structure-Activity Relationship ; Toluidines ; pharmacology ; Ubiquinone ; metabolism ; Virus Replication ; drug effects