Seasonal Flu - FAQs:

Certain groups of children are at increased risk for seasonal flu complications. Children at greater risk of serious flu-related complications include:

1. Children younger than 6 months old

The flu vaccine is not approved for use in infants younger than 6 months old; however, the risk of flu complications is higher in these young infants than it is for any other child age group. The best way to protect children younger than 6 months is to make sure members of their household and their caregivers are vaccinated.

2. Children aged 6 months up to their 5th birthday

It is estimated that each year in the U.S., there are more than 20,000 children younger than 5 years old who are hospitalized due to flu. Even children in this age group who are otherwise healthy are at risk simply because of their age. In addition, children 2 years of age up to their 5th birthday are more likely to be taken to a doctor, an urgent care center, or the emergency room because of flu than healthy older children. To protect their health, all children 6 months and older should be vaccinated against the flu each year. Vaccinating young children, their families, and other caregivers can also help protect them from getting sick.

3. Children aged 6 months and older with chronic health problems, including:

• asthma or other problems of the lungs;
• immune suppression;
• chronic kidney disease;
• heart disease;
• HIV/AIDS
• diabetes;
• sickle cell anemia; or
• long-term aspirin therapy;
• any condition that can reduce lung function (cognitive dysfunction, spinal cord injuries, seizure disorders, or other neuromuscular disorders).

In the United States, the peak of flu season has occurred anywhere from late November through March. The overall health impact (e.g., infections, hospitalizations, and deaths) of a flu season varies from year to year. CDC monitors circulating flu viruses and their related disease activity and provides influenza reports each week from October through May.

To learn about where the flu is spreading (by region), see the  Flu Activity and Surveillance CDC site: http://www.cdc.gov/flu/weekly/fluactivitysurv.htm.

Flu seasons are unpredictable in a number of ways. Although epidemics of flu happen every year, the timing, severity, and length of the epidemic depends on many factors, including what influenza viruses are spreading and whether they match the viruses in the vaccine.

The  2009-2010 season saw the emergence of the 2009 H1N1 influenza virus (previously called "novel H1N1" or "swine flu"). This virus caused the first influenza pandemic (global outbreak of disease caused by a new flu virus) in more than 40 years. While not certain, it is likely that 2009 H1N1 viruses will continue to spread for a third year along with seasonal viruses in the U.S. during the 2011-2012 flu season.

Influenza viruses can change in two different ways:

One is called "antigenic drift." These are small changes in the virus that happen continually over time. Antigenic drift produces new virus strains that may not be recognized by the body's immune system. This process works as follows: a person infected with a particular flu virus strain develops antibody against that virus. As newer virus strains appear, the antibodies against the older strains no longer recognize the "newer" virus, and reinfection can occur. This is one of the main reasons why people can get the flu more than one time. In most years, one or two of the three virus strains in the influenza vaccine are updated to keep up with the changes in the circulating flu viruses. So, people who want to be protected from flu need to get a flu shot every year.

The other type of change is called "antigenic shift." Antigenic shift is an abrupt, major change in the influenza A viruses, resulting in new hemagglutinin and/or new hemagglutinin and neuraminidase proteins in influenza viruses that infect humans. Shift results in a new influenza A subtype or a virus with a hemagglutinin or a hemagglutinin and neuraminidase combination that has emerged from an animal population that is so different from the same subtype in humans that most people do not have immunity to the new (e.g. novel) virus.

Such a “shift” occurred in the spring of 2009, when a new H1N1 virus with a new combination of genes emerged to infect people and quickly spread, causing a pandemic. When shift happens, most people have little or no protection against the new virus. While influenza viruses are changing by antigenic drift all the time, antigenic shift happens only occasionally. Type A viruses undergo both kinds of changes; influenza type B viruses change only by the more gradual process of antigenic drift.

Febrile seizures can occur when a child is sick with influenza virus infection or other childhood illnesses that may cause fever, and therefore, are usually seen during cold and flu season in the United States. However, several studies of children in the United States have shown no increased risk for febrile seizures following receipt of seasonal flu vaccines.

One study evaluated more than 45,000 children aged 6 months through 23 months of age who received influenza vaccines during 1991 through 2003 and did not find an association with seizures. In addition, there was no indication that seasonal flu vaccines or the 2009 H1N1 flu vaccines used in the United States during the 2009-2010 flu season were associated with an increased risk of febrile seizures.

However, during the 2010 influenza season in the Southern Hemisphere, febrile seizures were found to be associated with one formulation of influenza vaccine produced by CSL. Although this vaccine is not recommended for children in the United States, systems are in place to monitor adverse events, including seizures, after seasonal flu vaccines.

We know that reassortment occurs frequently in nature. Fortunately, reassortment rarely results in a virus with pandemic potential, though it has done so at least twice in the 20th century.

The influenza viruses that caused the 1957 and 1968 pandemics contained a mixture of gene segments from human and avian influenza viruses.  What is clear from genetic analysis of the viruses that caused these past pandemics is that reassortment (gene swapping) occurred to produce novel influenza viruses that caused the pandemics.  In both of these cases, the new viruses that emerged showed major differences from the parent viruses. 

However, not all viruses emerge directly from reassortment events. For example, the origins of the 1918 virus are not precisely known, but experts think it is likely that the 1918 virus may have resulted from a bird influenza virus directly infecting humans and pigs at about the same time without reassortment.

In communities where flu is circulating, treatment with flu antiviral agents is recommended for all hospitalized patients with confirmed, probable or suspected seasonal flu and for outpatients who are at higher risk for flu-related complications. Treatment of hospitalized patients with invasive pneumonia or related disease should include both flu antiviral agents and appropriate antibiotics.

Pneumococcal disease is a very serious illness in young children. Pneumococcal infections are now the most common cause of invasive bacterial infection in U. S. children. In the United States it is estimated that pneumococcal infections cause 100 deaths, 450 cases of meningitis, 4,000 cases of bacteremia or other invasive disease, and 3.1 million cases of otitis media (ear infections) annually in children under 5 years of age.

Meningitis is the most severe type of pneumococcal disease. Of children less than 5 years of age with pneumococcal meningitis, about 5% will die of their infection and others may have long-term problems such as hearing loss. Many children with pneumococcal pneumonia or blood stream infections will be ill enough to be hospitalized; about 1% of children with blood stream infections or pneumonia with a blood stream infection will die of their illness. Nearly all children with ear infections recover, although children with recurrent infections can suffer hearing loss.

Children at increased risk of pneumococcal infections include those with anatomic or functional asplenia (including sickle cell disease), patients taking immunosuppressive chemotherapy, those with congenital and acquired immune deficiency (including HIV infections), those with chronic renal disease and healthy Native American, Alaskan Native, and African American children. Children less than 60 months of age in out-of-home child care are at 2-3 fold higher risk of experiencing invasive pneumococcal infections than children in home care.

Rapid tests vary in their ability to detect flu viruses. Depending on the test used, the ability to detect last year's H1N1 flu can ranged from 10% to 70%. This means that some people with a 2009 H1N1 flu infection had a negative rapid test result. (This situation is called a false negative test result.)

Rapid tests appear to be better at detecting flu in children than adults. None of the rapid tests currently approved by the Food and Drug Administration (FDA) are able to distinguish 2009 H1N1 flu from other flu viruses. 

Novel influenza A viruses are viruses that are found in humans, but are not ordinary human subtypes (many novel flu viruses originate from animals, such as birds or pigs), or those that cannot be subtyped by standard methods.

Flu should never be dismissed as “just the flu.” It’s a serious disease, and while most cases are mild, some can be deadly. On average, seasonal flu is responsible for thousands of deaths every year in the United States —mainly among people 65 and older.

Children never expect to get sick. And some of them are perfectly healthy when they catch the flu. That’s why it’s important not to dismiss this serious disease.

Anyone with asthma is at higher risk for flu-related complications, such as pneumonia. Along with everyone else, if your child has asthma you should:

• Follow an updated, written Asthma Action Plan developed with your doctor. Follow this plan for daily treatment and for controlling your asthma symptoms.
   
• Make sure that his or her updated, written Asthma Action Plan is on file at school and/or at the child care center. Be sure that the plan and medication(s) are easy to get to when needed.
   
• Everyone with asthma who is older than 6 months should get a flu shot every year to protect against the seasonal flu. Children aged 6 months to 8 years who never have had a seasonal flu shot may need two doses the first time. Persons with asthma should not use the inhaled "FluMist®" vaccine.
   
• Certain antiviral drugs, prescribed by health care professionals, are medicines that fight the flu virus by stopping it from growing in your body. They make you feel better faster and may prevent serious flu problems. Flu treatments work best if they start within two days of when you get flu-like illness.
   
• Persons with flu infections might also get bacterial infections. These persons will also need to take antibiotics to fight the bacterial infection. Some signs of bacterial infection are severe or prolonged illness, or illness that seems to get better but then gets worse.
   
• Do not give aspirin (acetylsalicylic acid) to children or teenagers who have the flu. This can cause a rare, but serious, illness called Reye’s syndrome.

There are two types of influenza vaccines.  One is the inactivated influenza vaccine (“flu-shot”) that is given with a needle, usually in the arm.  This is the type of vaccine that Advisory Committee Immunization Practices (ACIP). recommends pregnant women should receive.

The other type of influenza vaccine, “nasal - spray” influenza vaccine (sometimes called LAIV for “live attenuated influenza vaccine”) is made with live weakened influenza virus.  The live attenuated (weakened) influenza vaccine is not recommended by the ACIP for use in pregnancy.

December 9, 2011-- CDC has confirmed two cases of human infection with two different novel influenza A viruses in different states (West Virginia and Minnesota). Both patients have fully recovered. While the viruses infecting both patients have been found in U.S. swine and some of the prior human infections with these viruses have been associated with direct or close swine contact, there are no reports of direct or close contact with swine prior to illness onset in either of these cases. Laboratory testing at CDC has confirmed that both novel viruses are susceptible to the antiviral medications oseltamivir (Tamiflu®) and zanamivir (Relenza®).

No ongoing community transmission of this virus has been detected in the United States as of December 9, 2011.

Learn more about these new viruses.

November 22, 2011-- The Iowa Department of Public Health today reported that a “novel strain of the influenza virus has been detected in three children.” All three of the children were reportedly mildly ill and have recovered. Iowa has increased surveillance for influenza-like-illness to detect any additional cases of infection with this novel virus.

Learn more about the Iowa illnesses.

Swine influenza (swine flu) is a respiratory disease of pigs caused by type A influenza viruses that regularly cause outbreaks of influenza in pigs. Swine flu viruses can cause high levels of illness in swine herds, but usually cause few deaths.

Common signs in sick pigs include fever, depression, coughing (barking), discharge from the nose or eyes, sneezing, breathing difficulties, eye redness or inflammation, and going off feed. However, influenza-infected pigs also may not appear ill or be only mildly ill.

Swine influenza viruses may circulate among swine throughout the year, but most outbreaks occur during the late fall and winter months similar to outbreaks of seasonal influenza in humans.

In the past, CDC received reports of approximately one human infected with influenza viruses that normally spread in swine every one to two years, but more recently, these cases have been detected more frequently. From December 2005 through December 2011, 35 cases of human infection with variant influenza have been reported.

The increased detection and reporting of these cases could be occurring for a number of reasons, including one or more of the following factors:

• First, pandemic preparedness efforts have improved state level surveillance and laboratory capacity to detect novel viruses in the United States.
• Second, in 2007, novel flu virus infections were made domestically and internationally reportable.
• And three, it’s also possible that there is a true increase in the number of these cases, possibly occurring from exposure to infected swine or through subsequent, limited human-to-human transmission.

People who have been infected with variant viruses have had symptoms similar to the symptoms of regular human seasonal influenza. These include:

• fever,
• lethargy,
• lack of appetite and
• coughing.

Some people also have reported runny nose, sore throat, eye irritation, nausea, vomiting, and diarrhea.

Viruses are like hijackers. They invade living, normal cells and use those cells to multiply and produce other viruses like themselves. This eventually kills the cells, which can make you sick.

Viral infections are hard to treat because viruses live inside your body's cells. They are "protected" from medicines, which usually move through your bloodstream. Antibiotics do not work for viral infections. There are a few antiviral medicines available. Vaccines can help prevent you from getting many viral diseases.

Bacteria are living things that have only one cell. Under a microscope, they look like balls, rods or spirals. They are so small that a line of 1,000 could fit across a pencil eraser. Most bacteria won't hurt you - less than 1 percent makes people sick. Many are helpful. Some bacteria help to digest food, destroy disease-causing cells and give the body needed vitamins. Bacteria are also used in making healthy foods like yogurt and cheese.

But infectious bacteria can make you ill. They reproduce quickly in your body. Many give off chemicals called toxins, which can damage tissue and make you sick. Examples of bacteria that cause infections include Streptococcus, Staphylococcus, and E. coli.

Antibioticsare the usual treatment. When you take antibiotics, follow the directions carefully. Each time you take antibiotics, you increase the chances that bacteria in your body will learn to resist them. Later, you could get or spread an infection that those antibiotics cannot cure.