- Published: October 1, 2022
- Updated: October 1, 2022
- University / College: University of Washington
- Language: English
- Downloads: 37
Introduction: The most effective way to prevent influenza is by getting the influenza vaccine (the flu shot) and using simple infection control measures such as hand washing. Antiviral medicines can also help prevent infection if you are exposed to the flu. This article will discuss ways to prevent infection with influenza. The symptoms and treatment of influenza are discussed separately. 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
Sneezing can transmit influenza. People who contract influenza are most infective between the second and third days after infection, and infectivity lasts for around ten days.[1] Children are much more infectious than adults and shed virus from just before they develop symptoms until two weeks after infection.[1][2] The transmission of influenza can be modeled mathematically, which helps predict how the virus will spread in a population.[3] Influenza can be spread in three main ways:[4][5]
* by direct transmission (when an infected person sneezes mucus directly into the eyes, nose or mouth of another person); * the airborne route (when someone inhales the aerosols produced by an infected person coughing, sneezing or spitting); * through hand-to-eye, hand-to-nose, or hand-to-mouth transmission,[6] either from contaminated surfaces or from 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.[7][8] 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.[4] Although a single sneeze releases up to 40, 000 droplets,[9] most of these droplets are quite large and will quickly settle out of the air.[4]
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.[4] As the influenza virus can persist outside of the body, it can also be transmitted by contaminated surfaces such as banknotes,[10] doorknobs, light switches and other household items.[11] 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.[12] However, if the virus is present in mucus, this can protect it for longer periods.[4] Avian influenza viruses can survive indefinitely when frozen.[13] They are inactivated by heating to 56 °C (133 °F) for a minimum of 60 minutes, as well as by acids (at pH <2).[13]
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Infection control
Reasonably effective ways to reduce the transmission of influenza include good personal health and hygiene habits such as: not touching your eyes, nose or mouth;[6] frequenthand washing (with soap and water, or with alcohol-based hand rubs);[6] covering coughs and sneezes; avoiding close contact with sick people; and staying home yourself if you are sick. Avoiding spitting is also recommended.[15] Although face masks might help prevent transmission when caring for the sick,[16][17] there is mixed evidence on beneficial effects in the community.[15][18] Smoking raises the risk of contracting influenza, as well as producing more severe disease symptoms.[19][20][21][22][23] 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.[24]
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.[25] In hospitals, quaternary ammonium compounds and bleach are used to sanitize rooms or equipment that have been occupied by patients with influenza symptoms.[25] At home, this can be done effectively with a diluted chlorine bleach.[26] 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.[27][28] 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.[15] When small numbers of people are infected, isolating the sick might reduce the risk of transmission. WHO recommendations
According to the WHO, you can decrease your chance of contracting the flu virus by taking the following steps:[14] * Get yourself (or family members age 6 months and older) vaccinated against current strains of influenza, if possible. * Keep your distance from people who show symptoms of influenza-like illness, such as coughing and sneezing (trying to maintain a distance of about 1 metre if possible); * Clean your hands thoroughly with soap and water, or cleanse them with an alcohol-based hand rub on a regular basis (especially if touching surfaces that are potentially contaminated); * Avoid touching your mouth, nose and eyes as much as possible; * 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); and ————————————————-
[edit]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
INFLUENZA VACCINE
Getting the influenza vaccine is the most effective way to reduce the chance of becoming infected with the flu. People who get the influenza vaccine have a lower chance of illness and death from influenza compared to people who are not vaccinated. (See” Seasonal influenza vaccination in adults” and “ Seasonal influenza vaccination in children”.) Timing — Because the influenza virus changes (or “ mutates”) slightly from year to year, you need a new influenza vaccine before each flu season. People should get the flu vaccine as soon as it is available to get the most benefit. In the northern hemisphere, the flu season usually occurs between November and April. In the southern hemisphere, the flu season usually occurs between May and October. Flu can occur at any time of year in the tropics. Effectiveness — People who are vaccinated form antibodies (proteins), which destroy the influenza virus after the person is exposed. It generally takes about two weeks to make these antibodies. The vaccine usually protects 50 to 80 percent of those who are vaccinated from getting the flu. If you get the flu after being vaccinated, your symptoms are likely to be milder and last for a shorter time compared to people who were not vaccinated. Injection versus nasal spray — The flu vaccine is available in three forms in the United States, as an injection into the muscle, as an injection into the skin, and as a nasal spray. *
The injection of the flu vaccine into the muscle (regular flu shot) is approved for adults and children 6 months and older. * Starting with the 2011 flu season, the flu vaccine can also be injected into the skin (intradermal). The intradermal injection uses a smaller needle and less vaccine but works as well as the regular flu shot. It is approved for adults aged 18 to 64 years. * The nasal spray is approved only for healthy children age 2 years and older and healthy adults up to 49 years. Pregnant women and people who have a weakened immune system or who have chronic medical problems should not get the nasal spray since it contains live virus. If you live with a person with a severely weakened immune system, you should not get the nasal spray. Vaccine side effects — The most common side effect of the flu shot is soreness at the injection site. People with a serious allergy to egg products should not receive the nasal spray because it is grown in eggs and its safety has not been studied in people with egg allergy. The flu vaccine that comes in a shot has been studied and shown to be safe even in people with egg allergy, so most people with an egg allergy can get the shot.
There is now also a flu shot that is not made in eggs (Flucelvax). People with egg allergy can receive this vaccine, but if it is not available, the egg-based flu shot is safe for most people. (See “ Patient information: Food allergy treatment and avoidance (Beyond the Basics)”.) Other possible side effects of these vaccines include body aches, headache, and a low-grade fever (usually less than 100. 4ºF or 38ºC). These problems are usually mild and go away within a day or two. Many people are concerned about the safety of vaccines. But for most people the risk of complications from the vaccine is much smaller than the risk of complications from being infected with the flu. While no vaccine is 100 percent safe for everyone, the flu vaccine appears to be low-risk. For example: * The flu vaccine is less likely than the flu itself to increase the risk of a nervous system disorder called Guillain-Barré syndrome. * There is no evidence that the flu vaccine increases the risk of birth defects or miscarriage. *
Some formulations of the flu vaccine contain a preservative called thimerosal, which is derived from mercury. However, there is no convincing evidence that the small amount of thimerosal in this vaccine will be harmful to children, pregnant women, or adults. (See “ Patient information: Why does my child need vaccines? (Beyond the Basics)”.) * Several groups, including the Vaccine Adverse Event Report System (VAERS, http://vaers. hhs. gov), monitor the reports of vaccine side effects closely. WHO SHOULD BE VACCINATED?
The flu vaccine is recommended for nearly all people 6 months of age and older. The vaccine is especially important for: * Adults age 50 or older.
* People who live in nursing homes and other long-term care facilities. * Adults and children who have chronic lung or heart conditions. This includes children with asthma. * Adults and children with chronic diseases such as diabetes or kidney disease. * Adults and children with HIV infection, or who have received organ or stem cell transplants. * Children and teenagers age 6 months to 18 years who are taking long-term aspirin therapy and might be at risk for Reye syndrome. * Women who will be pregnant during the influenza season. * Adults and children who might transmit influenza to high-risk individuals (including people listed above). This includes healthcare workers, workers in nursing homes, home health workers, and people who live with a high-risk individual. ANTIVIRAL MEDICINES
Antiviral medicines can help to reduce the chances of developing the flu after being exposed to someone who is infected. These medicines can also be used in certain people who are at risk for developing complications from the flu and who cannot receive the flu vaccine. The “ best” medicine depends on the strain of influenza circulating in the community. (See “ Prevention of seasonal influenza in adults” and “ Antiviral drugs for the prevention and treatment of seasonal influenza in children”.) INFECTION CONTROL
Infection control measures, like handwashing and covering your mouth when you cough, can help to prevent the spread of influenza [1]. * Frequent handwashing with soap and water can help limit the spread of influenza. You can use alcohol-based hand sanitizers when soap and water are not available. Whether you are infected with the flu or are caring for someone with the flu, you should wash your hands frequently. * Cover your mouth and nose while coughing or sneezing, and throw away dirty tissues immediately. Sneezing/coughing into the sleeve of your clothing (at the inner elbow) is another means of containing sprays of saliva and secretions and will not contaminate your hands. * Avoid touching your eyes, nose, and mouth since germs spread this way. * Avoid close contact with sick people.
* If you are sick with a flu–like illness, you should stay home for at least 24 hours after your fever is gone except to get medical care or for other necessities. Your fever should be gone without the use of a fever-reducing medicine. * While sick, limit contact with others as much as possible to keep from infecting them. More information about preventing the spread of flu is available from the United States Center for Disease Control and Prevention (http://www. cdc. gov/flu/protect/preventing. htm). WHERE TO GET MORE INFORMATION
Your healthcare provider is the best source of information for questions and
concerns related to your medical problem. This article will be updated as needed on our web site (www. uptodate. com/patients). Related topics for patients, as well as selected articles written for healthcare professionals, are also available. Some of the most relevant are listed below. Patient level information — UpToDate offers two types of patient education materials. The Basics — The Basics patient education pieces answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Patient information: Flu (The Basics)
Patient information: Vaccines for adults (The Basics)
Patient information: Vaccines and pregnancy (The Basics)
Patient information: Chronic bronchitis (The Basics)
Patient information: Bird flu (avian influenza) (The Basics) Beyond the Basics — Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are best for patients who want in-depth information and are comfortable with some medical jargon. Patient information: Influenza symptoms and treatment (Beyond the Basics) Patient information: Food allergy treatment and avoidance (Beyond the Basics) Patient information: Why does my child need vaccines? (Beyond the Basics) Professional level information — Professional level articles are designed to keep doctors and other health professionals up-to-date on the latest medical findings. These articles are thorough, long, and complex, and they contain multiple references to the research on which they are based. Professional level articles are best for people who are comfortable with a lot of medical terminology and who want to read the same materials their doctors are reading.
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