+ First Aid Supplies ®

Next Day Delivery
On Orders Placed Before 1pm
Free Shipping
On Orders Above €80
Order First Aid Supplies for Work, Schools, and more.
Delivering Throughout Ireland

Flu

Influenza


What is influenza?

Influenza, commonly called "the flu," is an illness caused by RNA viruses that infect the respiratory tract of many animals, birds, and humans. In most people, the infection results in the person getting fever, cough, headache, and malaise (tired, no energy); some people also may develop a sore throat, nausea, vomiting, and diarrhoea. The majority of individuals has symptoms for about one to two weeks and then recovers with no problems. However, compared with most other viral respiratory infections, such as the common cold, influenza (flu) infection can cause a more severe illness with a mortality rate (death rate) of about 0.1% of people who are infected with the virus.

The above is the usual situation for the yearly occurring "conventional" or "seasonal" flu strains. However, there are situations in which some flu outbreaks are severe. These severe outbreaks occur when the human population is exposed to a flu strain against which the population has little or no immunity because the virus has become altered in a significant way. Unusually severe worldwide outbreaks (pandemics) have occurred several times in the last hundred years since influenza virus was identified in 1933. By an examination of preserved tissue, the worst influenza pandemic (also termed the Spanish flu or Spanish influenza) occurred in 1918 when the virus caused between 40-100 million deaths worldwide, with a mortality rate estimated to range from 2%-20%.

In April 2009, a new influenza strain against which the world population has little or no immunity was isolated from humans in Mexico. It quickly spread throughout the world so fast that the WHO declared this new flu strain (termed novel H1N1 influenza A swine flu, often shortened to H1N1 or swine) as the cause of a pandemic on June 11, 2009. This was the first declared flu pandemic in 41 years. Fortunately, there was a worldwide response that included vaccine production, good hygiene practices (especially hand washing) were emphasized, and the virus (H1N1) caused far less morbidity and mortality than was expected and predicted. The WHO declared the pandemic's end on Aug. 10, 2010, because it no longer fit into the WHO's criteria for a pandemic.

Hemophilus influenzae is a bacterium that was incorrectly considered to cause the flu until the virus was demonstrated to be the correct cause in 1933. This bacterium can cause lung infections in infants and children, and it occasionally causes ear, eye, sinus, joint, and a few other infections, but it does not cause the flu.

What are the causes of the flu?

The flu (influenza) viruses

Influenza viruses cause the flu and are divided into three types, designated A, B, and C. Influenza types A and B are responsible for epidemics of respiratory illness that occur almost every winter and are often associated with increased rates of hospitalization and death. Influenza type C differs from types A and B in some important ways. Type C infection usually causes either a very mild respiratory illness or no symptoms at all; it does not cause epidemics and does not have the severe public-health impact of influenza types A and B. Efforts to control the impact of influenza are aimed at types A and B, and the remainder of this discussion will be devoted only to these two types.

Influenza viruses continually change over time, usually by mutation (change in the viral RNA). This constant changing often enables the virus to evade the immune system of the host (humans, birds, and other animals) so that the host is susceptible to changing influenza virus infections throughout life. This process works as follows: a host infected with influenza virus develops antibodies against that virus; as the virus changes, the "first" antibody no longer recognizes the "newer" virus and infection can occur because the host does not recognize the new flu virus as a problem until the infection is well under way. The first antibody developed may, in some instances, provide partial protection against infection with a new influenza virus. In 2009, almost all individuals had no antibodies that could recognize the novel H1N1 virus immediately.

Type A viruses are divided into types based on differences in two viral surface proteins called the hemagglutinin (H) and the neuraminidase (N). There are at least 16 known H subtypes and nine known N subtypes. These surface proteins can occur in many combinations. When spread by droplets or direct contact, the virus, if not killed by the host's immune system, replicates in the respiratory tract and damages host cells. In people who are immune compromised (for example, pregnant individuals,infants, cancer patients, asthma patients, people with pulmonary disease and many others), the virus can cause viral pneumonia or stress the individual's system to make them more susceptible to bacterial infections, especially bacterial pneumonia. Both pneumonia types, viral and bacterial, can cause severe disease and sometimes death.

                                 

Antigenic shift and drift

Influenza type A viruses undergo two kinds of changes. One is a series of mutations that occurs over time and causes a gradual evolution of the virus. This is called antigenic "drift." The other kind of change is an abrupt change in the hemagglutinin and/or the neuraminidase proteins. This is called antigenic "shift." In this case, a new subtype of the virus suddenly emerges. Type A viruses undergo both kinds of changes; influenza type B viruses change only by the more gradual process of antigenic drift and therefore do not cause pandemics.

A diagram that illustrates both antigenic shift and drift can be found athttp://www.medicinenet.com/swine_flu/page5.htm and shows how both mechanisms can lead to antigenically diverse virus strains. The 2009 pandemic-causing H1N1 virus is a classic example of antigenic shift. The U.S. Centres for Disease Control and Prevention (CDC) has indicated that novel H1N1 swine flu has an RNA genome that contains five RNA strands derived from various swine flu strains, two RNA strands from flu strains, and only one RNA strand from human flu strains. They suggest mainly antigenic shifts over about 20 years have led to the development of novel H1N1 flu virus.

What are flu symptoms in adults and in children?

Typical clinical features of influenza include fever (usually 100 F-103 F in adults and often even higher in children), respiratory symptoms such as

cough, sore throat, runny or stuffy nose, headache, muscle aches and fatigue, sometimes extreme.

Although nausea, vomiting, and diarrhoea can sometimes accompany influenza infection, especially in children, gastrointestinal symptoms are rarely prominent. The term "stomach flu" is a misnomer that is sometimes used to describe gastrointestinal illnesses caused by other micro-organisms. Novel H1N1 infections, however, have caused more nausea, vomiting, and diarrhoea than the conventional (seasonal) flu viruses.

Most people who get the flu recover completely in one to two weeks, but some people develop serious and potentially life-threatening medical complications, such as pneumonia. In an average year, influenza is associated with about 36,000 deaths nationwide and many more hospitalizations. Flu-related complications can occur at any age; however, the elderly and people with chronic health problems are much more likely to develop serious complications after the conventional influenza infections than are younger, healthier people. However, the novel H1N1 virus had developed a different pattern of infection. Unfortunately, the pattern of infection is similar to that of the 1918 "Spanish flu" pandemic in which young people (pregnant individuals, infants, teens, and adults through age 49) are the most susceptible populations worldwide. Analysis of the people who were likely to develop complications from the H1N1 infection showed that other groups of people were also susceptible, including American Indians, patients with COPD, and obese individuals.

What is the key to flu prevention?

Flu vaccine

Most of the illness and death caused by influenza can be prevented by annual influenza vaccination. The CDC's Advisory Committee on Immunization Practices (ACIP) issued recommendations for everyone 6 months of age and older who do not have any contraindications to vaccination, to receive a flu vaccine each year, beginning with the flu season of 2010-2011. ACIP recommends that children 6 months through 8 years of age receive two doses of the 2010-2011 flu vaccine with a minimal interval of four weeks unless they have received
at least one dose of 2009 H1N1 flu vaccine last season

And at least one dose of seasonal flu vaccine prior to the 2009-2010 flu season or two doses of 2009-2010 seasonal flu vaccine.

If a child has fulfilled both of these requirements, they only need one flu vaccine.
Flu vaccine (influenza vaccine made from inactivated and sometimes attenuated [non-infective] virus) is specifically recommended for those who are at high risk for developing serious complications as a result of influenza infection. The CDC lists these high-risk groups for conventional flu:

Pregnant women,

Children younger than 5, and especially children younger than 2 years;

People 50 years of age and older;

People of any age with certain chronic medical conditions such as asthma and diabetes;

People with immunosuppression, whether due to illness or medications;

People who live in nursing homes and other long-term care facilities;

People who live with or care for those at high risk for complications from flu, including

1. health-care workers,

2. Household contacts of people at high risk for complications from the flu,

3. Household contacts and out-of-home caregivers of children less than 6 months of age (no vaccine is approved for children younger than 6 months, as these children are too young to be vaccinated)

Other groups for whom conventional flu vaccine is specifically recommended are residents of nursing homes and other chronic-care facilities housing patients of any age with chronic medical conditions and children and teenagers who are receiving long-term aspirin therapy and who may therefore be at risk for developing Reye syndrome after an influenza virus infection. Influenza vaccine is also recommended for people who are in close or frequent contact with anyone in the high-risk groups defined above. These people include health-care personnel and volunteers who work with high-risk patients and people who live in a household with a high-risk person.

Are there any flu shot side effects in adults or in children?

Although annual influenza (injectable) vaccination has long been recommended for people in the high-risk groups, many still do not receive the vaccine, often because of their concern about side effects. They mistakenly perceive influenza as merely a nuisance and believe that the vaccine causes unpleasant side effects or that it may even cause the flu. The truth is that influenza vaccine causes no side effects in most people. The most serious side effect that can occur after influenza vaccination is an allergic reaction in people who have a severe allergy to eggs, since the viruses used in the vaccine are grown in hens' eggs. For this reason, people who have an allergy to eggs should not receive the influenza vaccine. Also, the vaccine is not recommended while individuals have active infections or active diseases of the nervous system. Less than one-third of those who receive the vaccine have some soreness at the vaccination site, and about 5%-10% experience mild side effects, such as headache, low-grade fever, or muscle cramps, for about a day after vaccination. These side effects are most likely to occur in children who have not been exposed to influenza virus in the past.

Nevertheless, some older people remember earlier influenza vaccines that did, in fact, produce more unpleasant side effects. Vaccines produced from the 1940s to the mid-1960s were not as highly purified as modern influenza vaccines, and it was these impurities that caused most of the side effects. Since the side effects associated with these early vaccines, such as fever, headache, muscle aches, and fatigue, were similar to some of the symptoms of influenza, people believed that the vaccine had caused them to get the flu. However, injectable influenza vaccine produced in the United States has never been capable of causing influenza because it consists of killed virus.

Another type of influenza vaccine (nasal spray) is made with live attenuated (altered) influenza viruses. This vaccine is made with live viruses that can stimulate the immune response enough to confer immunity but do not cause classic influenza symptoms (in most instances). The nasal spray vaccine (FluMist) is only approved for healthy individuals ages 2-49 years of age. This nasal spray vaccine contains live attenuated virus (less able to cause flu symptoms due to a designed inability to replicate at normal body temperatures). This live vaccine could possibly cause the disease in infants and immunocompromised people and does not produce a strong immune response in many older people. Side effects of the nasal mist include nasal congestion, sore throat, and fever. Headaches, muscle aches irritability, and malaise have also been noted. In most instances, if side effects occur, they only last a day or two. This nasal spray has been produced for conventional flu viruses and should not be given to pregnant individuals or anyone who has a medical condition that may compromise the immune system because in some instances the flu is the side effect. Caregivers should read the vaccine precaution insert before giving any vaccine, injectable or nasal, as these inserts are occasionally updated.

Some people do not receive influenza vaccine because they believe it is not very effective. There are several different reasons for this belief. People who have received influenza vaccine may subsequently have an illness that is mistaken for influenza, and they believe that the vaccine failed to protect them. In other cases, people who have received the vaccine may indeed have an influenza infection. Overall vaccine effectiveness varies from year to year, depending upon the degree of similarity between the influenza virus strains included in the vaccine and the strain or strains that circulate during the influenza season. Because the vaccine strains must be chosen nine to 10 months before the influenza season, and because influenza viruses mutate over time, sometimes mutations occur in the circulating virus strains between the time the vaccine strains are chosen and the next influenza season ends. These mutations sometimes reduce the ability of the vaccine-induced antibody to inhibit the newly mutated virus, thereby reducing vaccine efficacy. This commonly occurs with the conventional flu vaccines as the specific virus types chosen for vaccine inclusion are based on reasoned projections for the upcoming flu season.

Occasionally, the vaccine does not match the actual predominating virus strain and is not very effective in generating a specific immune response to the predominant infecting flu strain. For the 2010-11 flu season, the seasonal trivalent vaccine contains a H1N1 strain (swine flu strain) of virus that was one of the predominating pandemic viral strains in 2009-2010. Fortunately, it also contains the H3N2 virus that may predominate in 2010-2011, as reported H3N2 outbreaks have been reported.

Vaccine efficacy also varies from one person to another. Studies of healthy young adults have shown influenza vaccine to be 70%-90% effective in preventing illness. In the elderly and those with certain chronic medical conditions such as HIV, the vaccine is often less effective in preventing illness. Studies show the vaccine reduces hospitalization by about 70% and death by about 85% among the elderly who are not in nursing homes. Among nursing-home residents, vaccine can reduce the risk of hospitalization by about 50%, the risk of pneumonia by about 60%, and the risk of death by 75%-80%. If antigenic drift results in changing the circulating virus from the strains used in the vaccine, vaccine efficacy may be reduced. However, the vaccine is still likely to lessen the severity of the illness and to prevent complications and death.

Why should the influenza vaccine be taken every year?

Although only a few different influenza virus strains circulate at any given time, people may continue to become ill with the flu throughout their lives. The reason for this continuing susceptibility is that influenza viruses are continually mutating, through the mechanisms of antigenic shift and drift described above. Each year, the vaccine is updated to include the most current influenza virus strains that are infecting people worldwide. The fact that influenza viral genes continually change is one of the reasons vaccine must be taken every year. Another reason is that antibody produced by the host in response to the vaccine declines over time, and antibody levels are often low one year after vaccination. The CDC reports that the 2010-2011 seasonal influenza vaccine contains the following three viruses that comprise the trivalent vaccine:

an A/California/7/2009 (H1N1)-like virus;

an A/Perth/16/2009 (H3N2)-like virus;

and a B/Brisbane/60/2008-like virus.

This is the newest seasonal vaccine; there is no separate flu vaccine as there is no new pandemic flu strain like the H1N1 of 2009-2010. Fortunately, the 2010-11 trivalent vaccine is very effective as it contains at H3N2, which has been found in several flu outbreaks early in the 2010-2011 season.

Because of the vaccine synthesis and distribution problems with the pandemic H1N1 vaccines, a number of companies have begun development of new vaccine synthesis technologies to avoid the variable production quantities of virus and the long growth cycle and purification process in chicken eggs. There are at least five new technologically novel approaches under development (recombinant protein, virus-like particle synthesis, viral vectors, DNA-based vaccines [altered plasmids] and viral vectors that contain specific antigens). These methods are described in detail in the first reference. The CDC has indicated they plan to overhaul their vaccine distribution system, especially for those instances when a pandemic strain arises.

Many people still refuse to get flu shots because of misunderstandings, fear, or "because I never get any shots" or simply a belief that if they get the flu, they will do well. These are only some of the reasons, there are many more. The U.S. and other populations need to be better educated about vaccines; at least they should realize that safe vaccines have been around for many years (measles, mumps, chickenpox, and even a vaccine for cholera), and as adults they often have to get a vaccine-like shot to test for tuberculosis exposure. The flu vaccines are as safe as these vaccines and shots that are widely accepted by the public. Consequently, better efforts need to be made to make yearly flu vaccines as widely acceptable as other vaccines. Susceptible people need to understand that the vaccines afford them a significant chance to reduce or prevent this potentially debilitating disease, hospitalization and, in a few, lethal disease.

What are some treatments an individual can do at home for the flu?

First, individuals should be sure they are not members of a high-risk group that is more susceptible to getting severe flu symptoms. Check with your physician if you are unsure if you are a higher-risk person. Home care is recommended by the CDC if a person is normally healthy with no underlying diseases or conditions (for example, asthma, lung disease, pregnant, or immunosuppressed).

Increasing liquid intake, warm showers, and warm compresses, especially in the nasal area, can reduce the body aches and reduce nasal congestion. Nasal strips and humidifiers may help reduce congestion, especially while trying to sleep. Some physicians recommend nasal irrigation with saline to further reduces congestion; some recommend non-prescription decongestants. Fever can be treated with over-the counter acetaminophen (Tylenol) or ibuprofen (Motrin and others) (read labels for safe dosage). Cough can be suppressed by cough drops and over-the-counter cough syrup. If an individual's symptoms at home get worse, their doctor should be notified.

When should a person go to the emergency department for the flu?

The CDC has recently published guidelines on who should go to the emergency department for flu symptoms and who should not go. The CDC published these guidelines to avoid a crush of people going to the emergency department during the H1N1 flu pandemic and utilizing limited resources needed for true emergency patients such as cardiac or trauma patients and to avoid transmitting the virus to high-risk patients. The CDC guidelines are as follows for children and adults. The CDC urges normally healthy people who get the flu to stay home as the large majority of infected individuals will recover without antiviral medications or other treatments, and staying home should limit the viral spread.

The CDC urges people to seek emergency medical care for a sick child with any of these symptoms:

1. Fast breathing or trouble breathing

2. Bluish or grey skin colour

3. Not drinking enough fluids

4. Severe or persistent vomiting

5. Not waking up or not interacting

6. Being so irritable that the child does not want to be held

7. Flu-like symptoms improve but then return with fever and cough

The following is the CDC's list of symptoms that should trigger emergency medical care for adults:

1. Difficulty breathing or shortness of breath

2. Pain or pressure in the chest or abdomen

3. Sudden dizziness

4. Confusion

5. Severe or persistent vomiting

6. Flu-like symptoms improve but then return with fever and worse cough

7. Having a high fever for more than three days is another danger sign, according to the WHO, so the CDC has also included this as another serious symptom.

What are some treatments an individual can do at home for the flu?

First, individuals should be sure they are not members of a high-risk group that is more susceptible to getting severe flu symptoms. Check with your physician if you are unsure if you are a higher-risk person. Home care is recommended by the CDC if a person is normally healthy with no underlying diseases or conditions (for example, asthma, lung disease, pregnant, or immunosuppressed).

Increasing liquid intake, warm showers, and warm compresses, especially in the nasal area, can reduce the body aches and reduce nasal congestion. Nasal strips and humidifiers may help reduce congestion, especially while trying to sleep. Some physicians recommend nasal irrigation with saline to further reduces congestion; some recommend non-prescription decongestants. Fever can be treated with over-the counter acetaminophen (Tylenol) or ibuprofen (Motrin and others) (read labels for safe dosage). Cough can be suppressed by cough drops and over-the-counter cough syrup. If an individual's symptoms at home get worse, their doctor should be notified.

When should a person go to the emergency department for the flu?

The CDC has recently published guidelines on who should go to the emergency department for flu symptoms and who should not go. The CDC published these guidelines to avoid a crush of people going to the emergency department during the H1N1 flu pandemic and utilizing limited resources needed for true emergency patients such as cardiac or trauma patients and to avoid transmitting the virus to high-risk patients. The CDC guidelines are as follows for children and adults. The CDC urges normally healthy people who get the flu to stay home as the large majority of infected individuals will recover without antiviral medications or other treatments, and staying home should limit the viral spread.

The CDC urges people to seek emergency medical care for a sick child with any of these symptoms:

1. Fast breathing or trouble breathing

2. Bluish or grey skin colour

3. Not drinking enough fluids

4. Severe or persistent vomiting

5. Not waking up or not interacting

6. Being so irritable that the child does not want to be held

7. Flu-like symptoms improve but then return with fever and cough

The following is the CDC's list of symptoms that should trigger emergency medical care for adults:

1. Difficulty breathing or shortness of breath

2. Pain or pressure in the chest or abdomen

3. Sudden dizziness

4. Confusion

5. Severe or persistent vomiting

6. Flu-like symptoms improve but then return with fever and worse cough

7. Having a high fever for more than three days is another danger sign, according to the WHO, so the CDC has also included this as another serious symptom.

Who should receive the flu vaccine? When should someone get the flu shot?

In the United States, the flu season usually occurs from about November until April. Officials have decided each new flu season will start on Oct. 4. Typically, activity is very low until December, and peak activity most often occurs between January and March. Ideally, the conventional flu vaccine should be administered between September and mid-November. It takes about one to two weeks after vaccination for antibodies against influenza to develop and provide protection. The CDC has published a summary list of their current recommendations of who should get the 2010-2011 vaccine:

Summary of influenza vaccination recommendations, 2010

All people 6 months and older should be vaccinated annually.

Protection of people at higher risk for influenza-related complications should continue to be a focus of vaccination efforts as providers and programs transition to routine vaccination of all people 6 months and older.

When vaccine supply is limited, vaccination efforts should focus on delivering vaccination to people who

are 6 months to 4 years (59 months) of age;

are 50 years of age and older;

have chronic pulmonary (including asthma), cardiovascular (except hypertension), renal, hepatic, neurologic, hematologic, or metabolic disorders (including diabetes mellitus);

are immunosuppressed (including immunosuppression caused by medications or by human immunodeficiency virus);

are or will be pregnant during the influenza season;

are 6 months to 18 years of age and receiving long-term aspirin therapy and who therefore might be at risk for experiencing Reye's syndrome after influenza virus infection;

are residents of nursing homes and other chronic-care facilities;

are American Indians/Alaska natives;

are morbidly obese (body mass index is 40 or greater);

are health-care personnel;

are household contacts and caregivers of children aged younger than 5 years and adults aged 50 years and older, with particular emphasis on vaccinating contacts of children aged younger than 6 months;

And are household contacts and caregivers of people with medical conditions that put them at higher risk for severe complications from influenza.

As each flu season progresses and as the CDC refines its data from previous flu seasons and pandemics, this summary may be modified. The CDC publishes routine updates about the flu at Flu.gov and at http://www.cdc.gov/flu/weekly/fluactivity.htm.
   

Click Here To See Our Range Thermometers and Tongue Depressors