[머니투데이 김훈남기자][예방목적의 타미플루 복용으로 내성 발생]
항바이러스제인 타미플루에 내성을 보이는 변형 신종인플루엔자A(H1N1)가 사람을 통해 감염된 사례가 최초로 보고됐다.
20일(현지시간) 영국 BBC 뉴스는 "영국 카디프의 웨일즈 대학병원에서 5명의 변형 신종플루 감염자가 확인됐다"고 보도했다.
BBC에 따르면 이들 가운데 3명은 병원에서 사람에게 변형 신종플루가 전이된 경우다. 이전에도 타미플루에 내성을 보이는 신종플루 환자는 보고돼 왔지만 사람간 변형 신종플루 감염이 확인된 것은 전 세계 최초다.
5명의 환자 중 2명은 이미 증상에서 회복됐으며 2명은 일반 병실, 나머지 1명은 중환자실에서 집중치료를 받고 있다. 이에 대해 BBC 뉴스는 "타미플루에 내성을 보이는 변형 신종플루의 사람간 감염이 확인됨에 따라 공공보건에 심각한 위협으로 떠오르고 있다"고 평했다.
한편 세계보건기구(WHO)는 지난 9월 신종플루 보고서를 통해 타미플루의 내성 발생사례를 보고하며 "총 28건의 타미플루 내성사례 중 12건이 신종플루 예방목적으로 타미플루를 복용했기 때문"이라고 말했다. 이어 WHO는 "타미플루는 신종플루 증세를 보이는 환자만 복용해야 한다"며 신종플루 예방목적의 항바이러스제 사용을 경고했다.
세계보건기구(WHO)가 스위스 로슈사의 항바이러스제 오셀타미비르(상품명 타미플루)를 신종인플루엔자 예방목적으로 사용하지 말라고 경고했다.
25일(현지시간) WHO는 12번째 신종플루 보고서를 통해 타미플루 내성 발생사례를 발표했다. WHO는 타미플루 내성이 발생하는 주원인으로 면역억제증상을 보이는 환자와 예방차원에서 타미플루를 미리 복용한 환자를 들었다.
WHO는 총 28건의 타미플루 내성 사례가 발생했다며 그중 12건이 예방차원에서 타미플루를 복용했기 때문이라고 밝혔다. 6건은 심각한 면역억제 증상을 보이는 환자에게서, 4건은 치료목적으로 타미플루를 복용한 환자에게서 발견됐다고 덧붙였다. 2건은 타미플루를 복용하지 않은 환자들에게서 발견됐다.
보고서에 따르면 신종플루에 감염된 사람과 접촉해 예방차원에서 타미플루를 복용하는 것은 면역부전이나 합병증을 유발할 수 있다.
따라서 WHO는 신종플루 감염자와 접촉한 경험이 있는 사람에게는 증상이 나타나는지 여부를 면밀히 관찰하고 증상이 있을 경우에만 타미플루를 처방하라고 권장했다. 또 타미플루 내성을 보이는 신종플루 환자에게 대안으로 글락소스미스클라인사사의 자나미비르(상품명 리렌자)를 사용할 것을 권했다.
WHO는 타미플루에 내성을 보이는 바이러스가 아직 집계되지 않았지만 지역사회 감염이 있을 것이라며 예방차원의 타미플루 복용에 대해 경고했다.
6 October 2009 (originally posted on 21 May 2009)
Antiviral drugs are medicines that act directly on viruses to stop them from multiplying.
Yes, two antiviral drugs are being used to treat pandemic (H1N1) 2009 infection. These are oseltamivir and zanamivir, which both block the action of an influenza virus protein called neuraminidase. In clinical trials with seasonal influenza, these antiviral drugs have been shown to reduce the symptoms and duration of illness and may also contribute to preventing severe disease and death. Since these antivirals have been effective in treating seasonal influenza, they are also expected to be effective for pandemic (H1N1) 2009 infections.
There are two approved antiviral drugs for influenza that are available for treatment of pandemic influenza. These are the neuraminidase inhibitors oseltamivir and zanamivir, more commonly known by their trade names Tamiflu and Relenza.
Another class of approved antiviral drugs known as M2 inhibitors (amantadine and rimantadine) can be effective for treating seasonal influenza. However, the pandemic (H1N1) 2009 virus has been shown to be resistant to these particular antiviral drugs.
Studies show that early treatment, preferably within 48 hours after the first sign of symptoms, appear associated with better clinical outcome.
For patients who initially present with severe illness or whose condition begins to deteriorate, WHO recommends that treatment with oseltamivir should start immediately, no matter when illness started and without waiting for laboratory results.
For patients at risk for serious disease, including those with certain underlying medical conditions, WHO recommends treatment with either oseltamivir or zanamivir as soon as possible after the onset of symptoms and without waiting for the results of laboratory tests.
In all cases, where oseltamivir is unavailable or cannot be used for any reason, zanamivir may be given.
Antivirals should only be used when prescribed by a qualified health care provider, as they will be able to assess each situation and make the appropriate decisions on care. WHO recommends that all patients (including pregnant women) and all age groups (including young children and infants) should be treated with oseltamivir in the event of severe or deteriorating illness. Treatment with either oseltamivir or zanamivir should also be offered to all patients in at-risk groups in the event of illness, even if mild or uncomplicated.
Individuals that have been identified as “at-risk” of more complicated or severe illness associated with infection by influenza virus include:
The elderly (>65) appear less susceptible to infection by pandemic H1N1 influenza virus, but are assumed to be at higher risk of more severe or complicated illness if infected.
No, if antiviral drug treatment is indicated by the clinical presentation, then treatment should start as soon as possible. If there is a delay, treatment may be less effective.
For oseltamivir, the standard adult treatment course is one 75 mg capsule twice a day for five days. For severe or prolonged illness, physicians may decide to use a higher dose or continue the treatment for longer.
Zanamivir is taken as a powder by inhalation. The recommended dose for treatment of adults and children from the age of 5 years is two inhalations (2 x 5mg) twice daily for five days.
25 SEPTEMBER 2009 | GENEVA -- Growing international experience in the treatment of pandemic H1N1 virus infections underscores the importance of early treatment with the antiviral drugs, oseltamivir or zanamivir. Early treatment is especially important for patients who are at increased risk of developing complications, those who present with severe illness or those with worsening signs and symptoms.
The experience of clinicians, including those who have treated severe cases of pandemic influenza, and national authorities suggests that prompt administration of these drugs following symptom onset reduces the risk of complications and can also improve clinical outcome in patients with severe disease.
This experience further underscores the need to protect the effectiveness of these drugs by minimizing the occurrence and impact of drug resistance.
WHO encourages clinicians to be alert to two situations that carry a high risk for the emergence of viruses resistant to oseltamivir.
The risk of resistance is considered higher in patients with severely compromised or suppressed immune systems who have prolonged illness, have received oseltamivir treatment (especially for an extended duration), but still have evidence of persistent viral replication.
The risk of resistance is also considered higher in people who receive oseltamivir for so-called “post-exposure prophylaxis” following exposure to another person with influenza, and who then develop illness despite taking oseltamivir.
In both of these clinical situations, health care staff should respond with a high level of suspicion that oseltamivir resistance has developed. Laboratory investigation should be undertaken to determine whether resistant virus is present and appropriate infection control measures should be implemented or re-enforced to prevent spread of the resistant virus.
When a drug-resistant virus is detected, WHO further recommends that an epidemiological investigation be undertaken to determine whether onward transmission of the resistant virus has occurred. In addition, community surveillance for oseltamivir-resistant pandemic H1N1 virus strains should be enhanced.
In general, WHO does not recommend the use of antiviral drugs for prophylactic purposes. For people who have had exposure to an infected person and are at a higher risk of developing severe or complicated illness, an alternative option is close monitoring for symptoms, followed by prompt early antiviral treatment should symptoms develop.
WHO has also recommended against the use of a particular antiviral where the virus is known or highly likely to be resistant to it. For this reason, zanamivir is the treatment of choice for patients who become ill while on oseltamivir prophylaxis.
Systematic surveillance conducted by the Global Influenza Surveillance Network, supported by WHO Collaborating Centres and other laboratories, continues to detect sporadic incidents of H1N1 pandemic viruses that show resistance to oseltamivir. To date, 28 resistant viruses have been detected and characterized worldwide.
All of these viruses show the same H275Y mutation that confers resistance to the antiviral oseltamivir, but not to the antiviral zanamivir. Zanamivir remains a treatment option in symptomatic patients with severe or deteriorating illness due to oseltamivir-resistant virus.
Twelve of these drug-resistant viruses were associated with the use of oseltamivir for post-exposure prophylaxis. Six were associated with the use of oseltamivir treatment in patients with severe immunosuppression. Four were isolated from samples from patients receiving oseltamivir treatment.
A further two were isolated from patients who were not taking oseltamivir for either treatment or prophylaxis. Characterization of the remaining viruses is under way.
These numbers are comparatively small at present. Worldwide, more than 10,000 clinical specimens (samples and isolates) of the pandemic H1N1 virus have been tested and found to be sensitive to oseltamivir.
These data support several conclusions. Cases of oseltamivir-resistant viruses continue to be sporadic and infrequent, with no evidence that oseltamivir-resistant pandemic H1N1 viruses are circulating within communities or worldwide.
To date, person-to-person transmission of these oseltamivir resistant viruses has not been conclusively demonstrated. In some situations, however, local transmission may have occurred, but without any further onward or ongoing transmission.
Except for immunocompromised patients, those infected with an oseltamivir-resistant pandemic H1N1 virus have experienced typical uncomplicated influenza symptoms. No evidence suggests that oseltamivir-resistant viruses are causing a different or more severe form of illness.
The occurrence of oseltamivir-resistant viruses is expected and is consistent with observations from early clinical trials. As use of antiviral drugs continues to grow, further reports of drug-resistance viruses are certain to occur. WHO and its network of collaborating laboratories are closely monitoring the situation and will issue information and advice on a regular basis as indicated.
_______________________ Briefing Note on recommendations for use of antivirals