Amantadine and rimantadine for preventing and treating influenza A in adults

Structure and dynamics of the SARS-CoV-2 envelope protein monomer

Coronaviruses, especially severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), present an ongoing threat to human wellbeing. Consequently, elucidation of molecular determinants of their function and interaction with the host is an important task. Whereas some of the coronaviral proteins are extensively characterized, others remain understudied. Here, we use molecular dynamics simulations to analyze the structure and dynamics of the SARS-CoV-2 envelope (E) protein (a viroporin) in the monomeric form. The protein consists of the hydrophobic α-helical transmembrane domain (TMD) and amphiphilic α-helices H2 and H3, connected by flexible linkers. We show that TMD has a preferable orientation in the membrane, while H2 and H3 reside at the membrane surface. Orientation of H2 is strongly influenced by palmitoylation of cysteines Cys40, Cys43, and Cys44. Glycosylation of Asn66 affects the orientation of H3. We also observe that the monomeric E protein both generates and senses the membrane curvature, preferably localizing with the C-terminus at the convex regions of the membrane; the protein in the pentameric form displays these properties as well. Localization to curved regions may be favorable for assembly of the E protein oligomers, whereas induction of curvature may facilitate the budding of the viral particles. The presented results may be helpful for a better understanding of the function of the coronaviral E protein and viroporins in general, and for overcoming the ongoing SARS-CoV-2 pandemic.

Evidence that two instead of one defective interfering RNA in influenza A virus-derived defective interfering particles (DIPs) does not enhance antiviral activity

Influenza A virus (IAV) infection constitutes a significant health threat. Defective interfering particles (DIPs) can arise during IAV infection and inhibit spread of wild type (WT) IAV. DIPs harbor defective RNA segments, termed DI RNAs, that usually contain internal deletions and interfere with replication of WT viral RNA segments. Here, we asked whether DIPs harboring two instead of one DI RNA exert increased antiviral activity. For this, we focused on DI RNAs derived from segments 1 and 3, which encode the polymerase subunits PB2 and PA, respectively. We demonstrate the successful production of DIPs harboring deletions in segments 1 and/or 3, using cell lines that co-express PB2 and PA. Further, we demonstrate that DIPs harboring two instead of one DI RNA do not exhibit increased ability to inhibit replication of a WT RNA segment. Similarly, the presence of two DI RNAs did not augment the induction of the interferon-stimulated gene MxA and the inhibition of IAV infection. Collectively, our findings suggest that the presence of multiple DI RNAs derived from genomic segments encoding polymerase subunits might not result in increased antiviral activity.

Interplay between host non-coding RNAs and influenza viruses

Influenza virus infection through seasonal epidemics and occasional pandemics has been a major public health concern for decades. Incomplete protection from vaccination and increased antiviral resistance due to frequent mutations of influenza viruses have led to a continuous need for new therapeutic options. The functional significance of host protein and influenza virus interactions has been established, but relatively less is known about the interaction of host noncoding RNAs, including microRNAs and long noncoding RNAs, with influenza viruses. In this review, we summarize host noncoding RNA profiles during influenza virus infection and the regulation of influenza virus infection by host noncoding RNAs. Influenza viral non-coding RNAs are briefly discussed. Increased understanding of the molecular regulation of influenza viral replication will be beneficial in identifying potential therapeutic targets against the influenza virus.

Unification and extensive diversification of M/Orf3-related ion channel proteins in coronaviruses and other nidoviruses

The coronavirus, Severe Acute Respiratory Syndrome (SARS)-CoV-2, responsible for the ongoing coronavirus disease 2019 (COVID-19) pandemic, has emphasized the need for a better understanding of the evolution of virus-host interactions. ORF3a in both SARS-CoV-1 and SARS-CoV-2 are ion channels (viroporins) implicated in virion assembly and membrane budding. Using sensitive profile-based homology detection methods, we unify the SARS-CoV ORF3a family with several families of viral proteins, including ORF5 from MERS-CoVs, proteins from beta-CoVs (ORF3c), alpha-CoVs (ORF3b), most importantly, the Matrix (M) proteins from CoVs, and more distant homologs from other nidoviruses. We present computational evidence that these viral families might utilize specific conserved polar residues to constitute an aqueous pore within the membrane-spanning region. We reconstruct an evolutionary history of these families and objectively establish the common origin of the M proteins of CoVs and Toroviruses. We also show that the divergent ORF3 clade (ORF3a/ORF3b/ORF3c/ORF5 families) represents a duplication stemming from the M protein in alpha- and beta-CoVs. By phyletic profiling of major structural components of primary nidoviruses, we present a hypothesis for their role in virion assembly of CoVs, ToroVs, and Arteriviruses. The unification of diverse M/ORF3 ion channel families in a wide range of nidoviruses, especially the typical M protein in CoVs, reveal a conserved, previously under-appreciated role of ion channels in virion assembly and membrane budding. We show that M and ORF3 are under different evolutionary pressures; in contrast to the slow evolution of M as core structural component, the ORF3 clade is under selection for diversification, which suggests it might act at the interface with host molecules and/or immune attack.

Simultaneous determination of five antiviral drug residues and stability studies in honey using a two-step fraction capture coupled to liquid chromatography tandem mass spectrometry

An effective sample pretreatment method followed by liquid chromatography tandem mass spectrometry (LC-MS/MS) was first developed for simultaneous determination of five antiviral drug residues including ribavirin, moroxydine, amantadine, rimantadine and memantine in honey. To adsorb analytes with different binding properties and overcome the interference of sugars and uridine as endogenous ribavirin structural analogs in honey, the target drugs were extracted with 1% formic acid and then purified by a phenylboronic acid (PBA) solid phase extraction cartridge using two-step fraction capture prior to LC-MS/MS analysis. This method was validated by analyzing honey samples from nine floral origins including miscellaneous flowers, citrus, vitex, rape, acacia, sunflower, linden, buckwheat and jujube spiking at multiple levels, and the recoveries ranged from 82.46% to 116.34%, with relative standard deviations (RSDs) less than 14.58%. The limits of detection (LODs) and limits of quantitation (LOQs) of moroxydine, ribavirin, amantadine, rimantadine, and memantine were 0.1-2 µg/kg and 0.2-5 µg/kg, respectively. Depletion experiments of five antiviral drugs in honey at different storage and process temperatures demonstrated that moroxydine can potentially be used as a drug to cure sacbrood disease in honeybees.

Metabolic Profiling of a CB2 Agonist, AM9338, Using LC-MS and Microcoil-NMR: Identification of a Novel Dihydroxy Adamantyl Metabolite

Adamantyl groups are key structural subunit commonly used in many marketed drugs targeting diseases ranging from viral infections to neurological disorders. The metabolic disposition of adamantyl compounds has been mostly studied using LC-MS based approaches. However, metabolite quantities isolated from biological preparations are often insufficient for unambiguous structural characterization by NMR. In this work, we utilized microcoil NMR in conjunction with LC-MS to characterize liver microsomal metabolites of an adamantyl based CB2 agonist AM9338, 1-(3-(1H-1,2,3-triazol-1-yl) propyl)-N-(adamantan-1-yl)-1H-indazole-3-carboxamide, a candidate compound for potential multiple sclerosis treatment. We have identified a total of 9 oxidative metabolites of AM9338 whereas mono- or di-hydroxylation of the adamantyl moiety is the primary metabolic pathway. While it is generally believed that the tertiary adamantyl carbons are the preferred sites of CYP450 oxidation, both the mono- and di-hydroxyl metabolites of AM9338 show that the primary oxidative sites are located on the secondary adamantyl carbons. To our knowledge this di-hydroxylated metabolite is a novel adamantyl metabolite that has not been reported before. Further, the stereochemistry of both mono- and di-hydroxyl adamantyl metabolites has been determined using NOE correlations. Furthermore, docking of AM9338 into the CYP3A4 metabolic enzyme corroborates with our experimental findings, and the modelling results also provide a possible mechanism for the unusual susceptibility of adamantyl secondary carbons to metabolic oxidations. The novel dihydroxylated AM9338 metabolite identified in this study, along with the previously known adamantyl metabolites, gives a more complete picture of the metabolic disposition for adamantyl compounds.

Virulence-mediated infectiousness and activity trade-offs and their impact on transmission potential of influenza patients

Communicable diseases are often virulent, i.e. they cause morbidity symptoms in those infected. While some symptoms may be transmission-enhancing, other symptoms are likely to reduce transmission potential. For human diseases, the reduction in transmission opportunities is commonly caused by reduced activity. There is limited data regarding the potential impact of virulence on transmission potential. We performed an exploratory data analysis of 324 influenza patients at a university health centre during the 2016/2017 influenza season. We classified symptoms as infectiousness-related or morbidity-related and calculated two scores. The scores were used to explore the relationship between infectiousness, morbidity (virulence), and activity level. We found a decrease in the activity level with increasing morbidity scores. There was no consistent pattern between an activity level and an infectiousness score. We also found a positive correlation between morbidity and infectiousness scores. Overall, we find that increasing virulence leads to increased infectiousness and reduced activity, suggesting a trade-off that can impact overall transmission potential. Our findings indicate that a reduction of systemic symptoms may increase host activity without reducing infectiousness. Therefore, interventions should target both systemic- and infectiousness-related symptoms to reduce overall transmission potential. Our findings can also inform simulation models that investigate the impact of different interventions on transmission.

Respiratory viral infection: a potential "missing link" in the pathogenesis of COPD

Chronic obstructive pulmonary disease (COPD) is currently the third most common cause of global mortality. Acute exacerbations of COPD frequently necessitate hospital admission to enable more intensive therapy, incurring significant healthcare costs. COPD exacerbations are also associated with accelerated lung function decline and increased risk of mortality. Until recently, bacterial pathogens were believed to be responsible for the majority of disease exacerbations. However, with the advent of culture-independent molecular diagnostic techniques it is now estimated that viruses are detected during half of all COPD exacerbations and are associated with poorer clinical outcomes. Human rhinovirus, respiratory syncytial virus and influenza are the most commonly detected viruses during exacerbation. The role of persistent viral infection (adenovirus) has also been postulated as a potential pathogenic mechanism in COPD. Viral pathogens may play an important role in driving COPD progression by acting as triggers for exacerbation and subsequent lung function decline whilst the role of chronic viral infection remains a plausible hypothesis that requires further evaluation. There are currently no effective antiviral strategies for patients with COPD. Herein, we focus on the current understanding of the cellular and molecular mechanisms of respiratory viral infection in COPD.

Detection of adamantane-sensitive influenza A(H3N2) viruses in Australia, 2017: a cause for hope?

For over a decade virtually all A(H3N2) influenza viruses have been resistant to the adamantane class of antivirals. However, during the 2017 influenza season in Australia, 15/461 (3.3%) adamantane-sensitive A(H3N2) viruses encoding serine at residue 31 of the M2 protein were detected, more than the total number identified globally during the last 6 years. A return to wide circulation of adamantane-sensitive A(H3N2) viruses would revive the option of using these drugs for treatment and prophylaxis.

Investigation of the free energy profiles of amantadine and rimantadine in the AM2 binding pocket

The purpose of this work was to study the mechanism of drug resistance of M2 channel proteins by analyzing the interactions between the drugs amantadine and rimantadine and M2 channel proteins (including the wild type and the three mutants V27A, S31N, and G34A) and the drug binding pathways, by use of a computational approach. Our results showed that multiple drug-binding sites were present in the M2 channel, and the trajectory of the drugs through the M2 channel was determined. A novel method was developed to investigate of free energy profiles of the ligand-protein complexes. Our work provides a new explanation of the large amount of experimental data on drug efficacy.

Discovery of potential M2 channel inhibitors based on the amantadine scaffold via virtual screening and pharmacophore modeling

The M2 channel protein on the influenza A virus membrane has become the main target of the anti-flu drugs amantadine and rimantadine. The structure of the M2 channel proteins of the H3N2 (PDB code 2RLF) and 2009-H1N1 (Genbank accession number GQ385383) viruses may help researchers to solve the drug-resistant problem of these two adamantane-based drugs and develop more powerful new drugs against influenza A virus. In the present study, we searched for new M2 channel inhibitors through a combination of different computational methodologies, including virtual screening with docking and pharmacophore modeling. Virtual screening was performed to calculate the free energies of binding between receptor M2 channel proteins and 200 new designed ligands. After that, pharmacophore analysis was used to identify the important M2 protein-inhibitor interactions and common features of top binding compounds with M2 channel proteins. Finally, the two most potential compounds were determined as novel leads to inhibit M2 channel proteins in both H3N2 and 2009-H1N1 influenza A virus.

Influenza virus non-structural protein 1 (NS1) disrupts interferon signaling

Type I interferons (IFNs) function as the first line of defense against viral infections by modulating cell growth, establishing an antiviral state and influencing the activation of various immune cells. Viruses such as influenza have developed mechanisms to evade this defense mechanism and during infection with influenza A viruses, the non-structural protein 1 (NS1) encoded by the virus genome suppresses induction of IFNs-α/β. Here we show that expression of avian H5N1 NS1 in HeLa cells leads to a block in IFN signaling. H5N1 NS1 reduces IFN-inducible tyrosine phosphorylation of STAT1, STAT2 and STAT3 and inhibits the nuclear translocation of phospho-STAT2 and the formation of IFN-inducible STAT1:1-, STAT1:3- and STAT3:3- DNA complexes. Inhibition of IFN-inducible STAT signaling by NS1 in HeLa cells is, in part, a consequence of NS1-mediated inhibition of expression of the IFN receptor subunit, IFNAR1. In support of this NS1-mediated inhibition, we observed a reduction in expression of ifnar1 in ex vivo human non-tumor lung tissues infected with H5N1 and H1N1 viruses. Moreover, H1N1 and H5N1 virus infection of human monocyte-derived macrophages led to inhibition of both ifnar1 and ifnar2 expression. In addition, NS1 expression induces up-regulation of the JAK/STAT inhibitors, SOCS1 and SOCS3. By contrast, treatment of ex vivo human lung tissues with IFN-α results in the up-regulation of a number of IFN-stimulated genes and inhibits both H5N1 and H1N1 virus replication. The data suggest that NS1 can directly interfere with IFN signaling to enhance viral replication, but that treatment with IFN can nevertheless override these inhibitory effects to block H5N1 and H1N1 virus infections.

Influenza infection and COPD

Influenza is a disease with global impact that causes enormous morbidity and mortality on an annual basis. It primarily infects the respiratory tract and causes a broad range of illness ranging from symptomless infection to fulminant primary viral and secondary bacterial pneumonia. The severity of infection depends on both the virus strain and a number of host factors, primarily age and the presence of comorbid conditions such as cardiopulmonary disease. The mortality and utilization of healthcare resources associated with influenza is concentrated in the elderly and those with coexisting disease such as chronic obstructive pulmonary disease (COPD). Increasing use of vaccination and the development of new antiviral drugs hold out hope that the burden of disease associated with influenza can be reduced. However the constant emergence of new influenza strains and the current risk of avian influenza pandemic serve as warnings that influenza will remain a serious pathogen for the foreseeable future.

Complications of viral influenza

Viral influenza is a seasonal infection associated with significant morbidity and mortality. In the United States more than 35,000 deaths and 200,000 hospitalizations due to influenza occur annually, and the number is increasing. Children aged less than 1 year and adults aged more than 65 years, pregnant woman, and people of any age with comorbid illnesses are at highest risk. Annual vaccination is the cornerstone of prevention, but some older patients may derive less benefit from immunization than otherwise fit individuals. If started promptly, antiviral medications may reduce complications of acute influenza, but increasing resistance to amantadine and perhaps neuraminidase inhibitors underscores the need for novel prevention and treatment strategies. Pulmonary complications of influenza are most common and include primary influenza and secondary bacterial infection. Either may cause pneumonia, and each has a unique clinical presentation and pathologic basis. Staphylococcus aureus, including methicillin-resistant strains, is an important cause of secondary bacterial pneumonia with high mortality. During influenza season, treatment of pneumonia should include empiric coverage for this pathogen. Neuromuscular and cardiac complications are unusual but may manifest in persons of any age.

Amantadine and rimantadine for influenza A in children and the elderly

BACKGROUND

Although amantadine (AMT) and rimantadine (RMT) are used to relieve or treat influenza A symptoms in healthy adults, little is known about the effectiveness and safety of these antivirals in preventing and treating influenza A in children and the elderly.

OBJECTIVES

The aim of this review was to systematically consider evidence on the effectiveness and safety of AMT and RMT in preventing and treating influenza A in children and the elderly.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, 2007, issue 3); MEDLINE (1966 to July 2007) and EMBASE (1980 to July 2007).

SELECTION CRITERIA

Randomised or quasi-randomised trials comparing AMT and/or RMT in children and the elderly with placebo, control, other antivirals or comparing different doses or schedules of AMT and/or RMT or no intervention.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials for inclusion and assessed methodological quality. Disagreements were resolved by consensus. In all comparisons except for one, the trials in children and in the elderly were analysed separately. Data were analysed and reported using Cochrane Review Manager 4.2. software.

MAIN RESULTS

In children, RMT was effective in the abatement of fever on day three of treatment. AMT showed a prophylactic effect against influenza A infection. AMT and RMT were not related to an increase in the occurrence of adverse effects. RMT also was considered to be well tolerated by the elderly, but showed no prophylactic effect. Different doses were comparable in the prophylaxis of influenza in the elderly, as well as in reporting adverse effects. Zanamivir prevented influenza A more effectively than RMT in the elderly.

AUTHORS' CONCLUSIONS

AMT was effective in the prophylaxis of influenza A in children. As confounding matters might have affected our findings, caution should be taken when considering which patients should to be given this prophylactic. Our conclusions about effectiveness of both antivirals for the treatment of influenza A in children were limited to a proven benefit of RMT in the abatement of fever on day three of treatment. Due to the small number of available studies we could not reach a definitive conclusion on the safety of AMT or the effectiveness of RMT in preventing influenza in children and the elderly.

Antiviral therapy and prophylaxis for influenza in children

Antiviral agents are available that are safe and effective for the treatment and prophylaxis of influenza virus infections in children. The neuraminidase inhibitors (oseltamivir [Tamiflu] and zanamivir [Relenza]) are preferred agents because of current widespread resistance to the adamantanes (amantadine [Symmetrel] and rimantadine [Flumadine]). Therapy should be provided to children with influenza infection who are at high risk of severe infection and to children with moderate-to-severe influenza infection who may benefit from a decrease in the duration of symptoms. Prophylaxis should be provided (1) to high-risk children who have not yet received immunization and during the 2 weeks after immunization, (2) to unimmunized family members and health care professionals with close contact with high-risk unimmunized children or infants who are younger than 6 months, and (3) for control of influenza outbreaks in unimmunized staff and children in an institutional setting. Testing of current H5N1 avian influenza virus isolates, the potential agents of pandemic influenza, suggests susceptibility to oseltamivir and zanamivir. Because no prospective data exist on the efficacy of these agents in humans for H5N1 strains, the dosage and duration of therapy in adults and children may differ from those documented to be effective for epidemic influenza strains.

WHO Rapid Advice Guidelines for pharmacological management of sporadic human infection with avian influenza A (H5N1) virus

Recent spread of avian influenza A (H5N1) virus to poultry and wild birds has increased the threat of human infections with H5N1 virus worldwide. Despite international agreement to stockpile antivirals, evidence-based guidelines for their use do not exist. WHO assembled an international multidisciplinary panel to develop rapid advice for the pharmacological management of human H5N1 virus infection in the current pandemic alert period. A transparent methodological guideline process on the basis of the Grading Recommendations, Assessment, Development and Evaluation (GRADE) approach was used to develop evidence-based guidelines. Our development of specific recommendations for treatment and chemoprophylaxis of sporadic H5N1 infection resulted from the benefits, harms, burden, and cost of interventions in several patient and exposure groups. Overall, the quality of the underlying evidence for all recommendations was rated as very low because it was based on small case series of H5N1 patients, on extrapolation from preclinical studies, and high quality studies of seasonal influenza. A strong recommendation to treat H5N1 patients with oseltamivir was made in part because of the severity of the disease. Similarly, strong recommendations were made to use neuraminidase inhibitors as chemoprophylaxis in high-risk exposure populations. Emergence of other novel influenza A viral subtypes with pandemic potential, or changes in the pathogenicity of H5N1 virus strains, will require an update of these guidelines and WHO will be monitoring this closely.

Influenza and the vocal performer: update on prevention and treatment

Upper respiratory tract infections (URIs) are a major cause of morbidity among vocal arts professionals, both from their acute impairment of the vocal mechanism and their predisposing influence for the development of serious vocal sequelae. In this review, we present some of the salient features of currently available treatments effective against influenza, the virus family responsible for the most serious form of URI. At present, these include an inactivated vaccine and four antiviral drugs, each approved in the United States and many other countries for the prevention and treatment of influenza. A live attenuated vaccine is also available, and other vaccines and antiviral drugs are under development. This review details the current options available for treating both influenza and noninfluenza related URIs in the professional voice user.

Antivirals for influenza in healthy adults: systematic review

BACKGROUND

Use of antivirals is recommended for the control of seasonal and pandemic influenza. Our aim was to review the evidence of efficacy, effectiveness, and safety of registered antivirals against naturally occurring influenza in healthy adults.

METHODS

We searched various Databases to October, 2005, and contacted manufacturers and corresponding authors. We included randomised controlled trials comparing prophylactic (n=27) or treatment (n=27) efficacy against symptomatic or asymptomatic influenza. We did a meta-analysis and expressed prophylactic efficacy as a proportion (1-relative risk [RR]). For treatment trials, because of inconsistent and non-standardised reporting, we expressed continuous outcomes either as means or as hazard ratios.

FINDINGS

We included 51 reports of 52 randomised controlled trials. Amantadine prevented 61% (95% CI 35-76) of influenza A cases and 25% (13-36) of cases of influenza-like illness, but caused nausea (OR 2.56, 1.37-4.79), insomnia and hallucinations (2.54, 1.50-4.31), and withdrawals because of adverse events (2.54, 1.60-4.06). There was no effect on asymptomatic cases (RR 0.85, 0.40-1.80). In treatment, amantadine significantly shortened duration of fever compared with placebo (by 0.99 days, -1.26 to -0.71), but had no effect on nasal shedding of influenza A viruses (0.93, 0.71-1.21). The fewer data for rimantadine showed comparable effects. In prophylaxis, compared with placebo, neuraminidase inhibitors have no effect against influenza-like illness (1.28, 0.45-3.66 for oral oseltamivir 75 mg daily, 1.51, 0.77-2.95 for inhaled zanamivir 10 mg daily). Higher doses appear to make no difference. The efficacy of oral oseltamivir 75 mg daily against symptomatic influenza is 61% (15-82), or 73% (33-89) at 150 mg daily. Inhaled zanamivir 10 mg daily is 62% efficacious (15-83). Neither neuraminidase inhibitor appeared effective against asymptomatic influenza. Oseltamivir induces nausea (OR 1.79, 1.10-2.93), especially at higher prophylactic doses (2.29, 1.34-3.92). Oseltamivir in a post-exposure prophylaxis role has a protective efficacy of 58.5% (15.6-79.6) for households and from 68% (34.9-84.2) to 89% (67-97) in contacts of index cases. In influenza cases, compared with placebo the hazard ratios for time to alleviation of symptoms were 1.33, 1.29-1.37 for zanamivir; 1.30, 1.13-1.50 for oseltamivir provided medication was started within 48 h of symptom onset. Viral nasal titres were significantly diminished by both drugs (weighted mean difference -0.62, -0.82 to -0.41). Oseltamivir at 150 mg daily was effective in preventing lower respiratory tract complications in influenza cases (OR 0.32, 0.18-0.57). We could find no credible data on the effects of oseltamivir on avian influenza.

INTERPRETATION

The use of amantadine and rimantadine should be discouraged. Because of their low effectiveness, neuraminidase inhibitors should not be used in seasonal influenza control and should only be used in a serious epidemic or pandemic alongside other public-health measures.

Vaccines for preventing influenza in healthy children

BACKGROUND

In children and adults the consequences of influenza are mainly absences from school and work, however the risk of complications is greatest in children and people over 65 years old.

OBJECTIVES

To appraise all comparative studies evaluating the effects of influenza vaccines in healthy children; assess vaccine efficacy (prevention of confirmed influenza) and effectiveness (prevention of influenza-like illness) and document adverse events associated with receiving influenza vaccines.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 1, 2005); OLD MEDLINE (1966 to 1969); MEDLINE (1969 to December 2004); EMBASE (1974 to December 2004); Biological Abstracts (1969 to December 2004); and Science Citation Index (1974 to December 2004). We wrote to vaccine manufacturers and a number of corresponding authors of studies in the review.

SELECTION CRITERIA

Any randomised controlled trials (RCTs), cohort and case-control studies of any influenza vaccine in healthy children under 16 years old.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data.

MAIN RESULTS

Fifty-one studies involving 263,987 children were included. Seventeen papers were translated from Russian. Fourteen RCTs and 11 cohort studies were included in the analysis of vaccine efficacy and effectiveness. From RCTs, live vaccines showed an efficacy of 79% (95% confidence interval (CI) 48% to 92%) and an effectiveness of 33% (95% CI 28% to 38%) in children older than two years compared with placebo or no intervention. Inactivated vaccines had a lower efficacy of 59% (95% CI 41% to 71%) than live vaccines but similar effectiveness: 36% (95% CI 24% to 46%). In children under two, the efficacy of inactivated vaccine was similar to placebo. Thirty-four reports containing safety outcomes were included, 22 including live vaccines, 8 inactivated vaccines and 4 both types. The most commonly presented short-term outcomes were temperature and local reactions. The variability in design of studies and presentation of data was such that meta-analysis of safety outcome data was not feasible.

AUTHORS' CONCLUSIONS

Influenza vaccines are efficacious in children older than two years but little evidence is available for children under two. There was a marked difference between vaccine efficacy and effectiveness. That no safety comparisons could be carried out emphasizes the need for standardisation of methods and presentation of vaccine safety data in future studies. It was surprising to find only one study of inactivated vaccine in children under two years, given recent recommendations to vaccinate healthy children from six months old in the USA and Canada. If immunisation in children is to be recommended as public-health policy, large-scale studies assessing important outcomes and directly comparing vaccine types are urgently required.

Preventing influenza: an overview of systematic reviews

BACKGROUND

Many options are available for preventing people from getting infected by influenza virus, with vaccination being the most widely used.

METHODS

We assessed the evidence available in Cochrane systematic reviews. We found nine reviews, five of them addressing influenza vaccination, and four addressing medication.

RESULTS

Vaccination is effective in healthy adults and children, but the effect is modest in adults, and for young children few data are available. In patients with asthma, chronic obstructive pulmonary disease (COPD) and cystic fibrosis, more evidence is needed to determine effectiveness. Vaccination does not result in exacerbation of asthma. Neuraminidase inhibitors may also have a place in limiting the spread of infection, at least in adults. Amantadine and rimantadine seem effective but have unfavourable adverse-effect profiles. The popularity of homoeopathic Oscillococcinum, especially in France, is not supported by current evidence.

CONCLUSION

In many areas, more clinical trials are needed, as the current evidence is inconclusive. Furthermore, several other measures that may be helpful in preventing influenza that have not been addressed in Cochrane reviews.

Chinese medicinal herbs for influenza

BACKGROUND

Influenza is an acute respiratory communicable disease which can cause high morbidity and mortality in an epidemic. Traditional Chinese medicinal herbs following a particular theory may be a potential medicine of choice.

OBJECTIVES

The objective of this review was to assess the therapeutic effect and adverse reaction of Traditional Chinese medicinal herbs in treating uncomplicated influenza.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 3, 2004); MEDLINE (January 1966 to October 2004); EMBASE (January 1988 to October 2004); CBM (Chinese Biomedical Database) (January 1980 to December 2003); and the Chinese Cochrane Center's Controlled Trials Register (up to December 2003). We also searched Current Controlled Trials (www.controlled-trials.com) and the National Research Register (http://www.update-software.com/National/) for ongoing trials and reference lists of articles. We wrote to researchers in the field, or authors of studies evaluated in the review for more information.

SELECTION CRITERIA

Randomised and quasi-randomised trials comparing traditional Chinese medicinal herbs with placebo, or various other Chinese medicinal herbs, or with other current regimes normally used in care or comparing drugs with herbal preparations to simple drugs in treating defined uncomplicated influenza patients.

DATA COLLECTION AND ANALYSIS

At least two reviewers extracted data and assessed trial quality.

MAIN RESULTS

Eleven studies with the number of participants ranged from 52 to 479. In total 2,088 participants were included in the review. As the interventions of the included studies were different from each other and most of the studies were of low quality, we did not perform a summary meta-analysis. Some of the studies showed positive results favouring Traditional Chinese medicinal herb treatment compared to antiviral or antipyretic-analgesic drugs or the combination of them. Only three studies mentioned adverse reactions but no detailed data were acquired in the included studies. Eleven studies with the number of participants ranged from 52 to 479, 2,088 in total were included. As the interventions of the included studies were different from each other and most of the studies were of low quality, we failed to perform a summary meta-analysis. Some of the studies showed positive results favouring Traditional Chinese medicinal herb treatment compared to antiviral or antipyretic-analgesic drugs or the combination of them. Only three studies mentioned adverse reactions but no detailed data was acquired in the included studies.

AUTHORS' CONCLUSIONS

The small number of included studies and participants, as well as the low quality of most studies, made the evidence far from conclusive for clinical decision making, although traditional Chinese medicinal herbs as a whole seem to be comparatively or more effective compared to different chemical drugs. A certain herbal preparation could not be recommended for there was not enough evidence. More high quality randomised controlled trials (RCTs) with similar interventions are required to strengthen the evidence for the efficacy and safety of certain herbal preparation.

Antiviral treatment and prophylaxis of influenza in primary care: German recommendations

Antiviral drugs are a valuable supplementation to vaccines for the control and prevention of influenza. In Germany, for treating influenza amantadine, oseltamivir and zanamivir are approved. Amantadine and oseltamivir are also licensed for prophylactic use. On behalf of the Paul-Ehrlich-Society of Germany and the German Association for the Control of Virus Diseases, as two independent scientific societies, the first consensus Conference on the Antiviral Treatment and Prophylaxis of Influenza was held in June 2002. Based on the available data of clinical studies an expert group developed the following recommendations for the appropriate clinical use of the antiviral drugs: (1) since oseltamivir (orally administered) and zanamivir (administered by inhalation) have apparently similar clinical efficacy both drugs can be used alternatively for treatment. (2) Amantadine is not an alternative to the neuraminidase (NA) inhibitors because it is not effective against influenza B viruses, it frequently selects resistant virus mutants and it can cause adverse events. (3) When influenza is prevalent in the community patients with the clinical diagnosis of influenza should be treated with neuraminidase inhibitors if the symptoms are lasting not longer than 48 h. (4) Immunocompetent patients with a non-febrile illness and patients with a symptom history of more than 2 days should not be treated with antiviral drugs. (5) Although there are no data from clinical trials immunocompromised patients should also be treated when influenza has been diagnosed. (6) The prophylactic use of antiviral drugs can be recommended for persons with close contact to acutely ill persons and no recent vaccination against influenza. (7) The use of anti-influenza drugs have to be considered for prophylaxis in pandemics. A precondition for the adequate use of anti-influenza drugs in the primary medical care is the timely information on the local influenza situation delivered by surveillance systems.