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Influenza prevention involves taking steps that one can use to decrease their chances of contracting flu viruses, such as the Pandemic H1N1/09 virus, responsible for the 2009 flu pandemic.

Influenza transmission

People who contract influenza are most infective between the second and third days after infection and infectivity lasts for around ten days. Children are much more infectious than adults and shed virus from just before they develop symptoms until two weeks after infection. The transmission of influenza can be modeled mathematically, which helps predict how the virus will spread in a population.

Influenza can be spread in three main ways: by direct transmission when an infected person sneezes mucus into the eyes, nose or mouth of another person; through people inhaling the aerosols produced by infected people coughing, sneezing and spitting; and through hand-to-mouth transmission from either contaminated surfaces or direct personal contact, such as a hand-shake. The relative importance of these three modes of transmission is unclear, and they may all contribute to the spread of the virus. In the airborne route, the droplets that are small enough for people to inhale are 0.5 to 5 µm in diameter and inhaling just one droplet might be enough to cause an infection. Although a single sneeze releases up to 40,000 droplets, most of these droplets are quite large and will quickly settle out of the air. How long influenza survives in airborne droplets seems to be influenced by the levels of humidity and UV radiation: with low humidity and a lack of sunlight in winter probably aiding its survival.

As the influenza virus can persist outside of the body, it can also be transmitted by contaminated surfaces such as banknotes, doorknobs, light switches and other household items. The length of time the virus will persist on a surface varies, with the virus surviving for one to two days on hard, non-porous surfaces such as plastic or metal, for about fifteen minutes from dry paper tissues, and only five minutes on skin. However, if the virus is present in mucus, this can protect it for longer periods. Avian influenza viruses can survive indefinitely when frozen. They are inactivated by heating to 56 °C (133 °F) for a minimum of 60 minutes, as well as by acids (at pH <2).

Novel H1N1

According to the World Health Organization (WHO), 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 metre if possible)."

Further, according to the American Center for Disease Control and Prevention (CDC), the "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."

Infection Control

Good personal health and hygiene habits, like hand washing, avoiding spitting, and covering the nose and mouth when sneezing or coughing, are reasonably effective in reducing influenza transmission. In particular, hand-washing with soap and water, or with alcohol-based hand rubs, is very effective at inactivating influenza viruses. These simple personal hygiene precautions are recommended as the main way of reducing infections during pandemics. Although face masks might help prevent transmission when caring for the sick, there is mixed evidence on beneficial effects in the community. Smoking raises the risk of contracting influenza, as well as producing more severe disease symptoms. Thus, according to the laws of mathematical modelling of infectious diseases, smokers raise the exponential growth rates of influenza epidemics and may indirectly be responsible for a large percentage of influenza cases.

Since influenza spreads through both aerosols and contact with contaminated surfaces, surface sanitizing may help prevent some infections. Alcohol is an effective sanitizer against influenza viruses, while quaternary ammonium compounds can be used with alcohol so that the sanitizing effect lasts for longer. In hospitals, quaternary ammonium compounds and bleach are used to sanitize rooms or equipment that have been occupied by patients with influenza symptoms. At home, this can be done effectively with a diluted chlorine bleach.

During past pandemics, closing schools, churches and theaters slowed the spread of the virus but did not have a large effect on the overall death rate. It is uncertain if reducing public gatherings, by for example closing schools and workplaces, will reduce transmission since people with influenza may just be moved from one area to another; such measures would also be difficult to enforce and might be unpopular. When small numbers of people are infected, isolating the sick might reduce the risk of transmission.

WHO recommendations

According to the WHO, one can decrease their chances of contracting the flu virus by taking the following steps:

• Avoid touching one's 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 living spaces by opening windows;
• Practice good health habits including adequate sleep, eating nutritious food, and keeping physically active.

Preventing complications in children

Watch for emergency warning signs that need urgent medical attention. These warning signs include:

• Fast breathing or trouble breathing
• Bluish or gray skin color
• Not drinking enough fluids
• Not urinating or no tears when crying
• Severe or persistent vomiting
• Not waking up or not interacting
• Being so irritable that the child does not want to be held
• Pain or pressure in the chest or abdomen
• Sudden dizziness
• Confusion
• Flu-like symptoms improve but then return with fever and worse cough

Vaccination against H1N1

About 2.2 million doses of nasal spray are available so far, but the spray is not recommended for some of the people who are most in danger of complications from flu, including pregnant women and people with asthma. So while some priority groups like health care workers and healthy children 2 or older can get vaccinated this week, pregnant women and others at risk should wait.

At a Centers for Disease Control and Prevention press conference Tuesday, CDC officials said demand for the vaccine is so far outstripping supply, but they did not quantify by how much, according to the Associated Press' report.

The Famous Radio Ranch partnered with State Broadcast Associations and State Health Departments to create radio commercials, advising people to get their seasonal flu shot, as well as the H1N1 vaccine.

CDC recommendations

The CDC lists these as important ways to lower the risk of transmission:

• Cover the nose and mouth with a tissue when coughing or sneezing. Throw tissues in the trash after use;
• Wash hands often with soap and water, especially after coughing or sneezing. Alcohol-based hand cleaners are also effective;
• Avoid touching the eyes, nose, or mouth. Germs spread this way;
• Try to avoid close contact with sick people;
• Those sick with flu-like illness are recommended to stay home for at least 24 hours after their fever is gone, except to get medical care or for other necessities. (The fever should be gone without the use of a fever-reducing medicine.) The sickened are advised to keep away from others as much as possible to avoid making others sick.

Public opinion

A survey of Americans done in late June 2009 by the Harvard School of Public Health found that roughly 90% said they would be willing to avoid shopping malls, movie theaters, public transportation, and worship services for more than two weeks if health officials told them to. It also found that parents were worried about closures of schools or day care centers, with 43% saying they would lose pay or have money problems if they had to stay home a week or more because they were sick or had to care for someone. In the UK, the government established a National Pandemic Flu Service with a hotline and website, enabling persons with symptoms to get advice or obtain drugs without first getting a prescription from a doctor.

See also

• 2009 flu pandemic vaccine
• 2009 flu pandemic timeline
• 2009 flu pandemic tables
• 2009 flu pandemic by country
• Influenza
• Influenza vaccine

References

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External links

• World Health Organization: How to wash hands properly (PDF)
• World Health Organization: How to wash hands properly (Non-PDF)
• Center for Disease Control and Prevention: "2009 H1N1 Flu (Swine Flu)"

• Influenza