Clinical Management of Human Swine Influenza

1	Clinical Managem= ent of Human Swine Influenza Dr Lai Sik To, Thomas Consultant Physician Department of Medicine and Geriatrics Princess Margaret Hospital
2	Clinical Managem= ent Diagnosis Antiviral therapy General and supportive care Vaccine Healthcare approach
3	Clinical Managem= ent Diagnosis Antiviral therapy - ??? General and supportive care Vaccine Healthcare approach
4	Antiviral Therap= y Antivirals will be the only specific medical intervention on hand du= ring the initial pandemic response until pandemic vaccine becomes availab= le Susceptibility to antivirals is a cause for concern Available information suggest that the current strain of Human Swine Influenza (HSI) / Influenza A (H1N1) virus is Susceptible to neuraminidase inhibitors (oseltamivir (Tamiflu), zanamivir (Relenza) (MMWR Morb Mortal Wkly Rep, April 28, 2009) Resistant to adamantanes (amantadine, rimantidine) Clinical effectiveness of antiviral treatment of HSI is still unknow= n
5	Purposes for Ant= iviral Therapy Most patients with HSI experienced typical influenza-like symptoms a= nd recovered without the need for antiviral treatment; the benefits of antivirals may be modest in these patients Antivirals may reduce the symptoms and duration of illness, like for seasonal influenza; they may contribute to preventing severe disease= and death Can reduce viral shedding and transmission Some countries have decided to treat suspected patients as a part of public health measures to stop disease transmission
6	Use of Antiviral= Therapy Treatment Start antiviral as soon as possible Hospitalized confirmed, probable or suspected cases of HSI Patients at higher risk for influenza complications Best to start treatment within 48 hours of illness onset Recommended duration of treatment is five days Antivirals will be used in all cases who are ill or have pneumonia = even beyond 48 hours and may be at higher dosages and for longer duratio= n With evolvement into a pandemic which has a large number of people infected Antiviral use will be similar to that of seasonal influenza Treatment decisions are based on clinical judgment of the individu= al patient's risk on a case by case basis Paediatric age group is more commonly affected this time; need for Tamiflu suspension which is in short supply
7	Use of Antiviral= Therapy Treatment Recommended for the following high risk groups with HSI (similar to seasonal influenza= ) Adults 65 years of age and older Children younger than 5 years old (highest risk in < 2 years ol= d) Persons with the following conditions: Chronic pulmonary (including asthma), cardiovascular (except hypertension), renal, hepatic, haematological, neurological, neuromuscular, or metabolic disorders (including diabetes mellitu= s) Immunosuppression (including medications or HIV) Pregnant women Persons younger than 19 years of age who are receiving long-term aspirin therapy Residents of nursing homes and other chronic-care facilities
8	Use of Antiviral= Therapy Chemoprophylaxis in healthcare workers: Antivirals are immediately effective Recommended Given for 10 days after the last unprotected exposure, i.e. no PPE= or inappropriate PPE during close contact (within 1 metre) with a cas= e of HSI (confirmed or pending investigation result) during the infecti= ous period (7 days) Considered Healthcare workers in high risk areas caring for HSI (confirmed or pending investigation result) Healthcare workers with high risk of complications When WHO declares a pandemic, decision will be made on the use of p= re- and post-exposure prophylaxis for all healthcare workers in HA
9	Use of Antiviral= Therapy Chemoprophylaxis in the community: Household close contacts who are at high-risk for complications of influenza of confirmed or probable cases (recommended), or suspected cases (considered) Children attending school or day care who are at high-risk for complications of influenza and who had close contact (face-to-face) with a confirmed, probable or suspected case (considered) First responders who are at high-risk for complications of influenza and who are working in areas with confirmed cases of HSI infection (considered)
10	Use of Antiviral Therapy Chemoprophylaxis in the community: When a pandemic is declared, an urgent issue will be whether to continue the practice of giving antivirals prophylactically to all contacts of confirmed cases in the community For a group of 1000 people, 16 times as much antiviral is needed to prevent influenza infection as to treat it (Hayden F, Lancet Influe= nza Conference 2006) Sustainability of drug supply may be in question
11	Summary of Anti= viral Regimen for Treatment
12	Information for= the Use of Antivirals Oseltamivir (Tamiflu) Pregnancy and lactation Should only be used if the potential benefit justifies the potenti= al risk to the foetus or breast-fed baby Precaution Reduced dose for persons with renal impairment Contraindications In persons with known hypersensitivity to any of the components of= the product Adverse reactions Nausea, vomiting, abdominal pain, dyspepsia, diarrhoea; headache, fatigue, insomnia, dizziness, conjunctivitis, epistaxis; rash Very rarely hepatitis, Stevens-Johnson syndrome, and toxic epiderm= al necrolysis; neuropsychiatric disorders also reported (in children = and adolescents)
13	Information for= the Use of Antivirals Zanamivir (Relenza) Pregnancy and lactation The safe use during pregnancy has not been established It should be used during pregnancy only if the potential benefit justifies the potential risk to the foetus Avoid during breast-feeding Precautions Asthma and chronic pulmonary disease (risk of bronchospasm; uncontrolled chronic illness; other inhaled drugs should be administered before zanamivir Contraindications In persons with known hypersensitivity to any of the components of= the product. Adverse reactions Very rarely, bronchospasm, respiratory impairment, angioedema, urticaria and rash
14	Special Issue Pregnant women Both oseltamivir and zanamivir are FDA class C for use in pregnant women To date, no adverse effects have been reported among women who rece= ived oseltamivir or zanamivir during pregnancy or among infants born to = them One of the 3 pregnant women with HSI in the US died (MMWR May 12, 2= 009 / 58(Dispatch);1-3) Pregnant women who are close contacts should receive a 10-day cours= e of zanamivir or oseltamivir Because zanamivir is an inhaled medication and has less systemic absorption, some experts prefer zanamivir over oseltamivir in pregn= ant women
15	Special Issue Children under 1 year of age The use of oseltamivir is not licensed in Hong Kong in this age gro= up and informed consent should be obtained before commencement of treatment Reference can be taken from US CDC on a detailed description of the management of HSI virus infections in young children (Emergency Use Authorization (EUA))
16	General and Sup= portive Care Antibiotics Haemodynamic, ventilatory and organ support for ill cases in ICU Steroids and immunosuppressives – no supportive evidence and should be avoided Immune plasma Novel treatments, e.g. acetylcysteine, etc. Traditional Chinese Medicine
17	Vaccination= Vaccines against HSI are one of the most valuable ways to protect pe= ople during epidemics and pandemics WHO Collaborating Centres for influenza (WHO CCs), Essential Regulat= ory Laboratories (ERLs) and other institutions are developing candidate vaccine viruses under the coordination of WHO The first doses of HSI vaccine could be available in five to six mon= ths from identification of the pandemic strain Use of the new vaccine is still under consideration by WHO
18	Vaccination= Seasonal influenza vaccines could be associated with an increased ri= sk of Guillain-Barré syndrome at 1-2 cases per million vaccinated persons The 1976 swine flu vaccination campaign led to increased risk of aro= und 10 cases per million and the vaccine was withdrawn Close monitoring and investigation of all serious adverse events following administration of vaccine is essential and mandatory Taking antivirals does not interfere with the immune re= sponse to influenza vaccines
19	Vaccination= The evidence is incomplete but it suggests that seasonal vaccines wi= ll confer little or no protection against HSI Seasonal flu vaccination should still be continued: Facilitation of clinical diagnosis and management when seasonal flu= can be ruled out Prevention of gene re-assortment between viruses of HSI and seasonal influenza Pneumococcal vaccine for young age, elderly, the immunocompromised a= nd persons with chronic diseases will be considered
20	Healthcare Appr= oach Phases of public health action Containment – prevention of spread Mitigation – reduction of disease impact Containment phase Hospitalization and treatment of confirmed, probable and suspected cases in isolation wards Quarantine of asymptomatic contacts, preferably in holiday resorts instead of in hospita= ls
21	Healthcare Appr= oach Phases of public health action Containment – prevention of spread Mitigation – reduction of disease impact Containment phase Hospitalization and treatment of confirmed, probable and suspected cases in isolation wards Quarantine of asymptomatic contacts, preferably in holiday resorts instead of in hospita= ls
22	Healthcare Appr= oach Mitigation phase Aims at minimizing hospitalization, serious illness, overall deaths= and societal disruption Opening of HA designated clinics (DCs) with local outbreaks and increased caseload: Triage to identify ill cases for hospitalization Antivirals dispensed for mild cases with chronic illness and advice for home plan Symptomatic treatment of ordinary mild cases Antivirals will be used to control outbreaks in closed facilities for healthcare and long-term stay in both phases
23	Take Home Messa= ges The dosage and duration of antiviral treatment and prophylaxis for H= uman Swine Influenza is similar to seasonal influenza Human Swine Influenza vaccine can be made available in five to six mo= nths from identification of the pandemic strain
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