What is the new influenza A(H1N12009)?

What is the new influenza A(H1N1)?
This is a new influenza A(H1N12009) virus that has never before circulated among humans. This virus is not related to previous or current human seasonal influenza viruses.


How do people become infected with the virus?
The virus is spread from person-to-person. It is transmitted as easily as the normal seasonal flu and can be passed to other people by exposure to infected droplets expelled by coughing or sneezing that can be inhaled, or that can contaminate hands or surfaces.

To prevent spread, people who are ill should cover their mouth and nose when coughing or sneezing, stay home when they are unwell, clean their hands regularly, and keep some distance from healthy people, as much as possible.

There are no known instances of people getting infected by exposure to pigs or other animals.

The place of origin of the virus is unknown.

What are the signs and symptoms of infection?
Signs of influenza A(H1N12009) are flu-like, including fever, cough, headache, muscle and joint pain, sore throat and runny nose, and sometimes vomiting and diarrhoea.

Why are we so worried about this flu when hundreds of thousands die every year from seasonal epidemics?
Seasonal influenza occurs every year and the viruses change each year - but many people have some immunity to the circulating virus which helps limit infections. Some countries also use seasonal influenza vaccines to reduce illness and deaths.

But influenza A(H1N12009) is a new virus and one to which most people have no or little immunity and, therefore, this virus could cause more infections than are seen with seasonal flu. WHO is working closely with manufacturers to expedite the development of a safe and effective vaccine but it will be some months before it is available.

The new influenza A(H1N12009) appears to be as contagious as seasonal influenza, and is spreading fast particularly among young people (from ages 10 to 45). The severity of the disease ranges from very mild symptoms to severe illnesses that can result in death. The majority of people who contract the virus experience the milder disease and recover without antiviral treatment or medical care. Of the more serious cases, more than half of hospitalized people had underlying health conditions or weak immune systems.

Most people experience mild illness and recover at home. When should someone seek medical care?
A person should seek medical care if they experience shortness of breath or difficulty breathing, or if a fever continues more than three days. For parents with a young child who is ill, seek medical care if a child has fast or labored breathing, continuing fever or convulsions (seizures).

Supportive care at home - resting, drinking plenty of fluids and using a pain reliever for aches - is adequate for recovery in most cases. (A non-aspirin pain reliever should be used by children and young adults because of the risk of Reye's syndrome.)

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Questions & Answers:Novel H1N12009 Flu (Swine Flu) and You

Novel H1N1 Flu

What is novel H1N1 (swine flu)?
Novel H1N1 (referred to as “swine flu” early on) is a new influenza virus causing illness in people. This new virus was first detected in people in the United States in April 2009. This virus is spreading from person-to-person worldwide, probably in much the same way that regular seasonal influenza viruses spread. On June 11, 2009, the World Health Organization (WHO) signaled that a pandemic of novel H1N1 flu was underway.

Why is novel H1N1 virus sometimes called “swine flu”?
This virus was originally referred to as “swine flu” because laboratory testing showed that many of the genes in this new virus were very similar to influenza viruses that normally occur in pigs (swine) in North America. But further study has shown that this new virus is very different from what normally circulates in North American pigs. It has two genes from flu viruses that normally circulate in pigs in Europe and Asia and bird (avian) genes and human genes. Scientists call this a "quadruple reassortant" virus.

Novel H1N12009 Flu in Humans
Are there human infections with novel H1N1 virus in the U.S.?
Yes. Human infections with the new H1N1 virus are ongoing in the United States. Most people who have become ill with this new virus have recovered without requiring medical treatment.
CDC routinely works with states to collect, compile and analyze information about influenza, and has done the same for the new H1N1 virus since the beginning of the outbreak. This information is presented in a weekly report, called FluView.

Is novel H1N12009 virus contagious?
CDC has determined that novel H1N1 virus is contagious and is spreading from human to human.

How does novel H1N12009 virus spread?
Spread of novel H1N1 virus is thought to occur in the same way that seasonal flu spreads. Flu viruses are spread mainly from person to person through coughing or sneezing by people with influenza. Sometimes people may become infected by touching something – such as a surface or object – with flu viruses on it and then touching their mouth or nose.

What are the signs and symptoms of this virus in people?
The symptoms of novel H1N1 flu virus in people include fever, cough, sore throat, runny or stuffy nose, body aches, headache, chills and fatigue. A significant number of people who have been infected with this virus also have reported diarrhea and vomiting. Severe illnesses and death has occurred as a result of illness associated with this virus.

How severe is illness associated with novel H1N12009 flu virus?
Illness with the new H1N1 virus has ranged from mild to severe. While most people who have been sick have recovered without needing medical treatment, hospitalizations and deaths from infection with this virus have occurred.

In seasonal flu, certain people are at “high risk” of serious complications. This includes people 65 years and older, children younger than five years old, pregnant women, and people of any age with certain chronic medical conditions. About 70 percent of people who have been hospitalized with this novel H1N1 virus have had one or more medical conditions previously recognized as placing people at “high risk” of serious seasonal flu-related complications. This includes pregnancy, diabetes, heart disease, asthma and kidney disease.

One thing that appears to be different from seasonal influenza is that adults older than 64 years do not yet appear to be at increased risk of novel H1N1-related complications thus far. CDC laboratory studies have shown that children and few adults younger than 60 years old do not have existing antibody to novel H1N1 flu virus; however, about one-third of adults older than 60 may have antibodies against this virus. It is unknown how much, if any, protection may be afforded against novel H1N12009 flu by any existing antibody.

How does novel H1N12009 flu compare to seasonal flu in terms of its severity and infection rates?
With seasonal flu, we know that seasons vary in terms of timing, duration and severity. Seasonal influenza can cause mild to severe illness, and at times can lead to death. Each year, in the United States, on average 36,000 people die from flu-related complications and more than 200,000 people are hospitalized from flu-related causes. Of those hospitalized, 20,000 are children younger than 5 years old. Over 90% of deaths and about 60 percent of hospitalization occur in people older than 65.

When the novel H1N1 outbreak was first detected in mid-April 2009, CDC began working with states to collect, compile and analyze information regarding the novel H1N1 flu outbreak, including the numbers of confirmed and probable cases and the ages of these people. The information analyzed by CDC supports the conclusion that novel H1N1 flu has caused greater disease burden in people younger than 25 years of age than older people. At this time, there are few cases and few deaths reported in people older than 64 years old, which is unusual when compared with seasonal flu. However, pregnancy and other previously recognized high risk medical conditions from seasonal influenza appear to be associated with increased risk of complications from this novel H1N12009. These underlying conditions include asthma, diabetes, suppressed immune systems, heart disease, kidney disease, neurocognitive and neuromuscular disorders and pregnancy.

How long can an infected person spread this virus to others?
People infected with seasonal and novel H1N12009 flu shed virus and may be able to infect others from 1 day before getting sick to 5 to 7 days after. This can be longer in some people, especially children and people with weakened immune systems and in people infected with the new H1N12009 virus.

credit:cdc.gov

Question and AnSwer : A H1N1 2009 Use of antiviral drugs against influenza A(H1N1)

For what purposes can antiviral drugs be used against influenza A(H1N1)?
So far most people who have contracted the new A (H1N1) virus have experienced influenza-like symptoms (such as sore throat, cough, runny nose, fever, malaise, headache, joint/muscle pain) and recovered without antiviral treatment.

Antiviral drugs may reduce the symptoms and duration of illness, just as they do for seasonal influenza. They also may contribute to preventing severe disease and death. Influenza A (H1N1) is a new virus and only a small number of people with the infection have been treated for it with antiviral drugs. WHO is in touch with public health authorities and clinicians in affected countries and is gathering information about how effective the drugs are.

To which antiviral drugs does this influenza virus respond?
There are two classes of antiviral drugs for influenza: inhibitors of neuraminidase such as oseltamivir and zanamivir; and adamantanes, such as amantadine and rimantadine. Tests on viruses obtained from patients in Mexico and the United States have indicated that current new H1N1 viruses are sensitive to neuraminidase inhibitors, but that the viruses are resistant to the other class, the adamantanes.

Could the virus become resistant to oseltamivir and zanamivir?
Resistance can develop to antiviral drugs used for influenza. Therefore, WHO and its partners are monitoring antiviral drug resistance.

Under what circumstances should antiviral drugs be administered?
Antiviral drugs are to be used according to national pandemic influenza preparedness plans. Public health authorities in some countries have decided to treat patients likely to have this disease as a part of public health measures.

Where antiviral drugs are available for treatment, clinicians should make decisions based on assessment of the individual patient's risk. Risks versus benefits should also be evaluated on a case by case basis.

Should I take an antiviral now just in case I catch the new virus?
No. You should only take an antiviral, such as oseltamivir or zanamivir, if your health care provider advises you to do so. Individuals should not buy medicines to prevent or fight this new influenza without a prescription, and they should exercise caution in buying antivirals over the internet.

Warning on purchase of antivirals without a prescription, including via the Internet [pdf 35kb]

What is WHO doing about getting antiviral drugs to countries as preparation for a pandemic?
WHO’s first priority is to provide an emergency stock of antiviral drugs to countries that have no or insufficient stock of the drugs and lack the capacity to procure these drugs themselves.

WHO is also working with Member States, donors and other groups that have stockpiles and are willing to share these with WHO for distribution to countries in need.

Which drug will be provided, and how much of it does WHO have available?
WHO had a global stockpile of approximately 5 million adult treatment courses of oseltamivir. Part of this stockpile has already been distributed through the WHO Regional Offices, which are handling allocation and distribution. WHO is currently distributing the remaining 3 million adult treatment courses of this stockpile to developing countries in need.

WHO continues to assess needs and to work with manufacturers to secure more donations of antivirals. More antiviral drugs will be distributed once these donations are received.

Which countries will receive the drug, and how will they be selected?
WHO has arranged the first deployment of antiviral drugs from the WHO stockpile to 72 countries. Priority was given to vulnerable countries, taking into consideration national manufacturing and procurement capacity. As necessary, other countries will be supported through regional office stockpiles.

What if the initial emergency deployment turns out to be inadequate?
WHO is in discussion with manufacturers regarding the potential need for scaling up production. It is WHO’s understanding that manufacturers have plans for producing large numbers of treatments quickly.

WHO will work on behalf of its Member States to secure further antivirals as needed, either through donations or purchase at the lowest possible price.

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Is it safe to travel?

Is it safe to travel?
Yes. WHO is not recommending travel restrictions related to the outbreak of the influenza A(H1N1) virus. Today, global travel is commonplace and large numbers of people move around the world for business and leisure. Limiting travel and imposing travel restrictions would have very little effect on stopping the virus from spreading, but would be highly disruptive to the global community.

Influenza A(H1N12009) has already been confirmed in many parts of the world. The global response now focuses on minimizing the impact of the virus through the rapid identification of cases, and providing patients with appropriate medical care, rather than on stopping its spread internationally.

Although identifying signs and symptoms of influenza in travellers can help track the path of the outbreak, it will not reduce the spread of influenza, as the virus can be transmitted from person to person before the onset of symptoms.

Scientific research based on mathematical modelling shows that restricting travel would be of limited or no benefit in stopping the spread of disease. Historical records of previous influenza pandemics, as well as experience with SARS, validate this.

Does WHO recommend screenings at country entry and exit points to detect if ill people are travelling? No. We do not believe entry and exit screenings would work to reduce the spread of this disease. However country-level measures to respond to a public health risk are the decision of national authorities, under the International Health Regulations 2005.

Countries that adopt measures that significantly interfere with international traffic (e.g. delaying an airplane passenger for more than 24 hours, or refusing country entry or departure to a traveller) must provide WHO with the public health reasoning and evidence for their actions. WHO will follow up with all of its Member countries on such matters.

Travellers should always be treated with dignity and respect for their human rights.

How can I protect myself from influenza A(H1N1) when I am travelling?
People who are ill should delay travel plans. Returning travellers who become ill should contact their health care provider.

Travellers can protect themselves and others by following simple prevention practices that apply while travelling and in daily life.

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Pandemic influenza in pregnant women

Pandemic H1N1 2009 briefing note 5
31 JULY 2009 | GENEVA -- Research conducted in the USA and published 29 July in The Lancet [1] has drawn attention to an increased risk of severe or fatal illness in pregnant women when infected with the H1N1 pandemic virus.

Several other countries experiencing widespread transmission of the pandemic virus have similarly reported an increased risk in pregnant women, particularly during the second and third trimesters of pregnancy. An increased risk of fetal death or spontaneous abortions in infected women has also been reported.

Increased risk for pregnant women
Evidence from previous pandemics further supports the conclusion that pregnant women are at heightened risk.

While pregnant women are also at increased risk during epidemics of seasonal influenza, the risk takes on added importance in the current pandemic, which continues to affect a younger age group than that seen during seasonal epidemics.

WHO strongly recommends that, in areas where infection with the H1N1 virus is widespread, pregnant women, and the clinicians treating them, be alert to symptoms of influenza-like illness.

WHO recommendations for treatment
Treatment with the antiviral drug oseltamivir should be administered as soon as possible after symptom onset. As the benefits of oseltamivir are greatest when administered within 48 hours after symptom onset, clinicians should initiate treatment immediately and not wait for the results of laboratory tests.

While treatment within 48 hours of symptom onset brings the greatest benefits, later initiation of treatment may also be beneficial. Clinical benefits associated with oseltamivir treatment include a reduced risk of pneumonia (one of the most frequently reported causes of death in infected people) and a reduced need for hospitalization.

WHO has further recommended that, when pandemic vaccines become available, health authorities should consider making pregnant women a priority group for immunization.

Danger signs in all patients
Worldwide, the majority of patients infected with the pandemic virus continue to experience mild symptoms and recover fully within a week, even in the absence of any medical treatment. Monitoring of viruses from multiple outbreaks has detected no evidence of change in the ability of the virus to spread or to cause severe illness.

In addition to the enhanced risk documented in pregnant women, groups at increased risk of severe or fatal illness include people with underlying medical conditions, most notably chronic lung disease (including asthma), cardiovascular disease, diabetes, and immunosuppression. Some preliminary studies suggest that obesity, and especially extreme obesity, may be a risk factor for more severe disease.

Within this largely reassuring picture, a small number of otherwise healthy people, usually under the age of 50 years, experience very rapid progression to severe and often fatal illness, characterized by severe pneumonia that destroys the lung tissue, and the failure of multiple organs. No factors that can predict this pattern of severe disease have yet been identified, though studies are under way.

Clinicians, patients, and those providing home-based care need to be alert to danger signs that can signal progression to more severe disease. As progression can be very rapid, medical attention should be sought when any of the following danger signs appear in a person with confirmed or suspected H1N1 infection:

•shortness of breath, either during physical activity or while resting
•difficulty in breathing
•turning blue
•bloody or coloured sputum
•chest pain
•altered mental status
•high fever that persists beyond 3 days
•low blood pressure.
In children, danger signs include fast or difficult breathing, lack of alertness, difficulty in waking up, and little or no desire to play.

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[1] Jamiesan DG et al. H1N1 2009 influenza virus infection during pregnancy in the USA. Lancet 2009; published online July 29, 2009

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