Conceptional considerations for a German influenza pandemic preparedness plan

Preclinical in vitro activity of QR-435 against influenza A virus as a virucide and in paper masks for prevention of viral transmission

Prophylaxis against influenza is difficult, and current approaches against pandemics may be ineffective because of shortages of the two proven classes of antivirals in the face of a large-scale infection. Herbal/natural products may represent an effective alternative to conventional attempts to protect against infection by avian influenza virus. QR-435, an all-natural compound of green tea extract and other agents, has been developed to provide protection against a wide range of viral infections. The antiviral activities of several QR-435 preparations as well as QR-435 (1) green tea extract were tested against A/Sydney/5/97 and A/Panama-Resvir 17 strains of avian influenza virus H3N2 by means of an assay based on Madin-Darby canine kidney cells. Toxic effects of QR-435 formulations on these cells were also evaluated as were the virucidal properties of a commercially available mask impregnated with QR-435. The efficacy of a QR-435/mask combination was compared with that of the QR control/mask combination, an untreated mask, and no mask. QR-435 had significant in vitro activity against H3N2 at concentrations that were not associated with significant cellular toxic effects. The antiviral activity of QR-435 (1) was similar to that of QR-435. Masks impregnated with QR-435 were highly effective in blocking the passage of live H3N2 virus. These preclinical results warrant further evaluation of the prophylactic use of QR-435 against viral infection in humans.

In vivo prophylactic activity of QR-435 against H3N2 influenza virus infection

BACKGROUND

Prophylaxis against influenza infection can take several forms, none of which is totally effective at preventing the spread of the disease. QR-435, an all-natural compound of green-tea extract and other agents, has been developed to protect against a range of viral infections, including the influenza subtype H3N2.

METHODS

Several different QR-435 formulations were tested against the two influenza A H3N2 viruses (A/Sydney/5/97 and A/Panama/2007/99) in the ferret model. Most experiments included negative (phosphate-buffered saline) and positive (oseltamivir 5 mg/kg, twice daily) controls. QR-435 and the control were administered 5 minutes after intranasal delivery of the virus as prophylaxis against infection resulting from exposure to infected but untreated ferrets and for prevention of transmission from infected and treated ferrets to untreated animals. Effects of QR-435 on seroconversion, virus shedding, and systemic sequelae of infection (weight loss, fever, reduced activity) were evaluated.

RESULTS

QR-435 prevented transmission and provided prophylaxis against influenza virus H3N2. Prophylaxis with QR-435 was significantly more than with oseltamivir in these experiments. Optimal in vivo efficacy of QR-435 requires a horseradish concentration of at least 50% of that in the original formulation, and the benefits of this preparation appear to be dose dependent.

CONCLUSIONS

QR-435 is effective for both prevention of H3N2 viral transmission and prophylaxis. These preclinical results warrant further evaluation of its prophylactic properties against avian influenza virus infection in humans.

Limitations of current prophylaxis against influenza virus infection

Avian influenza has been a source of worldwide concern since Hong Kong authorities detected the first outbreak in 1997. Mainly as a result of poultry-to-human transmission, more than 200 cases of infection in humans have been attributed to the A/H5, A/H7, and A/H9 viral subtypes, with a case fatality rate for A/H5N1 infections exceeding 50%. A mutant or reassortant virus capable of efficient human-to-human transmission can set off a pandemic. Increased attention to prophylaxis against viral infection has identified several potentially complementary approaches: nonpharmacologic measures (eg, travel restrictions), vaccination, chemotherapeutic agents, and herbal/natural products. All have significant limitations that point out the need for additional modalities. Herbal/natural products, particularly those based on green tea extract, offer promise as adjuncts or alternatives to current interventions and warrant further evaluation in well-controlled human trials.

Interactions between influenza and bacterial respiratory pathogens: implications for pandemic preparedness

It is commonly believed that the clinical and epidemiological characteristics of the next influenza pandemic will mimic those of the 1918 pandemic. Determinative beliefs regarding the 1918 pandemic include that infections were expressed as primary viral pneumonias and/or acute respiratory distress syndrome, that pandemic-related deaths were the end states of the natural progression of disease caused by the pandemic strain, and that bacterial superinfections caused relatively fewer deaths in 1918 than in subsequent pandemics. In turn, response plans are focused on developing and/or increasing inventories of a strain-specific vaccine, antivirals, intensive care beds, mechanical ventilators, and so on. Yet, there is strong and consistent evidence of epidemiologically and clinically important interactions between influenza and secondary bacterial respiratory pathogens, including during the 1918 pandemic. Countermeasures (eg, vaccination against pneumococcal and meningococcal disease before a pandemic; mass uses of antibiotic(s) with broad spectrums of activity against common bacterial respiratory pathogens during local epidemics) designed to prevent or mitigate the effects of influenza-bacterial interactions should be major focuses of pandemic-related research, prevention, and response planning.

Preparing for an influenza pandemic: ethical issues

In the near future, experts predict, an influenza pandemic will likely spread throughout the world. Many countries have been creating a contingency plan in order to mitigate the severe health and social consequences of such an event. Examination of the pandemic plans of Canada, the United Kingdom and the United States, from an ethical perspective, raises several concerns. One: scarcity of human and material resources is assumed to be severe. Plans focus on prioritization but do not identify resources that would be optimally required to reduce deaths and other serious consequences. Hence, these plans do not facilitate a truly informed choice at the political level where decisions have to be made on how much to invest now in order to reduce scarcity when a pandemic occurs. Two: mass vaccination is considered to be the most important instrument for reducing the impact of infection, yet pandemic plans do not provide concrete estimates of the benefits and burdens of vaccination to assure everyone that the balance is highly favorable. Three: pandemic plans make extraordinary demands on health care workers, yet professional organizations and unions may not have been involved in the plans' formulation and they have not been assured that authorities will aim to protect and support health care workers in a way that corresponds to the demands made on them. Four: all sectors of society and all individuals will be affected by a pandemic and everyone's collaboration will be required. Yet, it appears that the various populations have been inadequately informed by occasional media reports. Hence, it is essential that plans are developed and communication programs implemented that will not only inform but also create an atmosphere of mutual trust and solidarity; qualities that at the time of a pandemic will be much needed.