Novel Influenza A (H1N1) FAQs

Influenza A(H1N1)

What is the new influenza A(H1N1)?
This is a new influenza A(H1N1) 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(H1N1) are flu-like, including fever, cough, headache, muscle and joint pain, sore throat and runny nose, and sometimes vomiting and diarrhea.

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(H1N1) 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. World Health Organization 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(H1N1) 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.)

What to do

What can I do to protect myself from catching influenza A(H1N1)?
The main route of transmission of the new influenza A(H1N1) virus seems to be similar to seasonal influenza, via droplets that are expelled by speaking, sneezing or coughing. You can prevent getting infected by avoiding close contact with people who show influenza-like symptoms (trying to maintain a distance of about 1 meter if possible) and taking the following measures:
  • avoid touching your mouth and nose;
  • clean hands thoroughly with soap and water, or cleanse them with an alcohol-based hand rub on a regular basis (especially if touching the mouth and nose, or surfaces that are potentially contaminated);
  • avoid close contact with people who might be ill;
  • reduce the time spent in crowded settings if possible;
  • improve airflow in your living space by opening windows;
  • practice good health habits including adequate sleep, eating nutritious food, and keeping physically active.

What about using a mask? What does World Health Organization recommend?
If you are not sick you do not have to wear a mask.

If you are caring for a sick person, you can wear a mask when you are in close contact with the ill person and dispose of it immediately after contact, and cleanse your hands thoroughly afterwards.

When and how to use a mask? World Health Organization Advice on Masks

If you are sick and must travel or be around others, cover your mouth and nose.

Using a mask correctly in all situations is essential. Incorrect use actually increases the chance of spreading infection.

How do I know if I have influenza A(H1N1)?
You will not be able to tell the difference between seasonal flu and influenza A(H1N1) without medical help. Typical symptoms to watch for are similar to seasonal viruses and include fever, cough, headache, body aches, sore throat and runny nose. Only your medical practitioner and local health authority can confirm a case of influenza A(H1N1).

What should I do if I think I have the illness?
If you feel unwell, have high fever, cough or sore throat:
  • stay at home and keep away from work, school or crowds;
  • rest and take plenty of fluids;
  • cover your nose and mouth when coughing and sneezing and, if using tissues, make sure you dispose of them carefully. Clean your hands immediately after with soap and water or cleanse them with an alcohol-based hand rub;
  • if you do not have a tissue close by when you cough or sneeze, cover your mouth as much as possible with the crook of your elbow;
  • use a mask to help you contain the spread of droplets when you are around others, but be sure to do so correctly;
  • inform family and friends about your illness and try to avoid contact with other people;
  • If possible, contact a health professional before traveling to a health facility to discuss whether a medical examination is necessary.

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

What about breastfeeding? Should I stop if I am ill?
No, not unless your health care provider advises it. Studies on other influenza infections show that breastfeeding is most likely protective for babies - it passes on helpful maternal immunities and lowers the risk of respiratory disease. Breastfeeding provides the best overall nutrition for babies and increases their defense factors to fight illness.

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.)

Should I go to work if I have the flu but am feeling OK?
No. Whether you have influenza A(H1N1) or a seasonal influenza, you should stay home and away from work through the duration of your symptoms. This is a precaution that can protect your work colleagues and others.

Can I travel?
If you are feeling unwell or have symptoms of influenza, you should not travel. If you have any doubts about your health, you should check with your health care provider.

Vaccination Information

Will the new pandemic influenza A (H1N1) vaccines be safe?
Licensed vaccines, including influenza vaccines, are held to a very high standard of safety. Likewise, all possible precautions will be taken to ensure safety of new pandemic vaccines and results from clinical trials, currently ongoing or soon to be initiated, will be taken into consideration by the regulatory authorities in their decision to license pandemic vaccines. In early June 2009, World Health Organization (WHO) held a consultation of experts which reviewed the safety of adjuvants, or substances added to vaccines to make them more effective; no significant safety concerns were identified. Vaccine safety will be carefully monitored through post-marketing surveillance.

How can a repeat of the 1976 swine flu vaccine complications (Guillain-Barré syndrome) experienced in the United States of America be avoided?
Guillain-Barré Syndrome (GBS) is an acute disorder of the nervous system. It sometimes develops following a variety of infections, including influenza. Studies suggest that seasonal influenza vaccines could sometimes be associated with an increased risk of Guillain-Barré syndrome on the order of one to two cases per million vaccinated persons. During the 1976 influenza vaccination campaign, about 10 persons per million vaccinated persons developed GBS which stopped the vaccination campaign and led to the withdrawal of the vaccine.

The reason why GBS developed in association with that specific vaccine has never been firmly established. The potential for the development of a similar risk with future vaccines can never be firmly excluded. However, the influenza A (H1N1) vaccine will be manufactured according to established standards and post marketing surveillance will be conducted to monitor potential development of any serious adverse events following administration of vaccine. Safety monitoring systems are an integral part of strategies for the implementation of the new pandemic influenza vaccines.

Who will approve (license) new influenza A (H1N1) vaccines for use?
Regulatory approval for new influenza A (H1N1) vaccines will be conducted by the Center for Disease Control and Prevention (CDC). National regulatory authorities have put into place expedited processes that do not compromise on the quality and safety of the vaccine.

Is a vaccine against pandemic influenza A (H1N1) virus available to immunize people?
No, but work is well under way to develop such a vaccine. Making new influenza vaccines ready to immunize people generally takes five to six months after first identification of the pandemic virus. The pandemic influenza A (H1N1) 2009 virus was identified at the end of April 2009.

How quickly will pandemic influenza A (H1N1) vaccines be available for use?
The very first doses of influenza A (H1N1) vaccine usable to immunize people, from one or more manufacturers, are expected as early as September 2009.

What technologies will be used to grow pandemic influenza A (H1N1) viruses to make vaccines?
Most of these vaccines will be produced using chicken eggs, while a few manufacturers are using cell culture technology for vaccine production.

Will there be enough pandemic influenza A (H1N1) vaccine for everyone?
When pandemic vaccine first becomes available, it is anticipated that the demand will be greater than the supply. This gap will narrow as more vaccine becomes available over time. Vaccine will first be made available to priority groups, then to the rest of the population. There will eventually be vaccine available for everyone that wants one.

Who will receive priority for vaccination?
The Center for Disease Control and Preventions Advisory Committee on Immunization Practices (ACIP), a panel made up of medical and public health experts identified several priority groups to receive novel influenza A (H1N1) influenza vaccine based on those at most risk of falling ill and developing medical complications due to influenza. They include:
  • Pregnant women
  • Household contacts and caregivers for children younger than 6 months of age
  • Healthcare and emergency medical services personnel
  • All people from 6 months through 24 years of age
  • Persons aged 25 through 64 years who have health conditions associated with higher risk of complications from influenza.

Will it be possible to deliver influenza A (H1N1) vaccine simultaneously with other vaccines?
Inactivated influenza vaccine can be given at the same time as other injectable non-influenza vaccines, but the vaccines should be administered at different injection sites. Advice is being developed at present by regulatory authorities on co-administration of pandemic and seasonal influenza vaccines and will be provided when available.

How can a person who wishes to be vaccinated against influenza A (H1N1) receive the vaccine?
Once the first doses of pandemic influenza A (H1N1) vaccine become available, state and local health authorities will decide how to implement community vaccination programs.

Will current seasonal influenza vaccines offer any protection against influenza A (H1N1) infection?
So far, evidence suggests that it is unlikely that seasonal influenza vaccines will be protective against the new pandemic virus.

When is production of seasonal influenza vaccine likely to be completed?
More than 90% of seasonal influenza vaccine production for the Northern Hemisphere (2009-10) is expected to be completed by the end of July. Analysis of epidemiological evidence available in September 2009 will be critical to determine the composition of the Southern Hemisphere's 2010-11 seasonal influenza vaccine, and how much vaccine will be needed.

Should people continue to be vaccinated against seasonal influenza?
National health authorities do not propose any changes to standard seasonal flu vaccination recommendations. People should therefore continue to seek seasonal influenza vaccination like any other year.

More on World Health Organization travel recommendations

Updated 11 June 2009