Flu/Colds

Overview

What Is It?
The flu, or influenza, is a viral disease of the respiratory tract—the nose, throat, bronchial tubes and lungs—and is highly contagious. A cold is a less severe viral infection, and often includes a runny nose, sneezing and coughing. Unlike flu, colds typically don't cause fever.

The flu, or influenza, is a viral disease of the respiratory tract—the nose, throat, bronchial tubes and lungs—and is highly contagious. It is spread though airborne droplets of moisture produced by coughs or sneezes. When you breathe these germs in through your nose or mouth, you may come down with the flu, generally within one to three days of exposure.

The flu is a potentially serious disease that can lead to hospitalization, or, in severe cases, death. Even healthy people can become very sick from the flu. Death rates from the flu vary from season to season. Flu-related death estimates have ranged from a low of 12,000 to a high of 56,000 from 2010 to 2014, according to the U.S. Centers for Disease Control and Prevention (CDC).

Outbreaks frequently start in school-age children, who carry the virus home and spread it to other groups.

And, beginning with the 2009-2010 flu season, there was a new flu to contend with—H1N1 flu ("swine flu"), which caused the first flu pandemic in more than 40 years. Since this outbreak, the seasonal flu vaccines have included coverage for the 2009 H1N1 flu. The seasonal trivalent flu vaccine usually contains one of each of the three kinds of influenza viruses that most commonly circulate among people today: influenza A (H1N1), influenza A (H3N2) and influenza B viruses. See the Prevention section for more information.

Flu seasons are unpredictable. There are some flu outbreaks every season, but it's impossible to predict the timing, severity and length of the flu season from year to year. Health officials say 2017-2018 was a bad season, with the highest number of flu-related hospitalizations ever recorded. The flu season in the United States commonly peaks in January or February, but it can begin as early as October and continue into May.

Because flu can be so serious and can spread so rapidly, the CDC recommends that everyone age 6 months and older get vaccinated every year. The nasal spray flu vaccine (FluMist Quadrivalent) is available this year after two years off market in the U.S. It is an option for non-pregnant people ages 2 through 49 years of age. The nasal spray is a four-component (quadrivalent) live attenuated influenza vaccine. Most regular egg-based flu shots also contain four strains of flu virus though there are three-strain (trivalent) options. Shots may or may not contain live strains, depending on what your health care professional recommends for you.

A yearly flu vaccine is the first and most important step in protecting against flu, according to the CDC.

Vaccines are especially important to those most susceptible to flu complications, including older people, children, pregnant women, people who are morbidly obese, people with compromised immune systems and those with chronic illnesses such as heart disease, kidney disease, asthma, COPD and diabetes. The most serious, often life-threatening complication of the flu is pneumonia. Other complications include ear infection, bronchitis, dehydration and worsening of chronic conditions, such as congestive heart failure, asthma or diabetes. Croup and a lung disease called bronchiolitis can also arise as complications in infants and young children.

In addition, the severity of illness is increased by exposure to cigarette smoke, which can injure airways and damage the cilia, the tiny hair-like structures that help keep airways clear. Toxic fumes, industrial smoke and other air pollutants are also risk factors.

There is also evidence that influenza can be more dangerous for women in their second or third trimester of pregnancy. The strain and stress of pregnancy on a woman's lungs, combined with the type of influenza, can lead to pulmonary problems, although there doesn't appear to be any danger to the fetus from the influenza virus itself.

There are three strains of the flu virus:

• Type A results in severe illness that easily spreads throughout a population, even globally, affecting a large number of people at the same time.
• Type B is a generally less severe strain that tends to affect fewer people.
• Type C causes very mild symptoms, so mild that many people don't even realize they're sick.

The influenza virus changes its genetic makeup every year. That's why you can get the flu every year and why a flu vaccine containing the new virus is recommended annually for everyone 6 months and older.

This constantly changing virus presents a particular challenge to medical science, making it impossible to create a single vaccine to prevent the disease. Instead, the World Health Organization (WHO) and the CDC monitor each new strain of influenza virus as it appears, assessing which may be the predominant virus in the following year's flu season. Scientists use this data, collected by a surveillance network, to develop a vaccine each year against the specific virus they predict will predominate. For the 2018-2019 season, the standard quadrivalent flu vaccine contains two influenza A viruses (H1N1 and H3N2) and two influenza B viruses.

Ask your health care professional for more information about restrictions and availability of flu vaccine or visit the CDC's website.

In terms of prevention and treatment, drugs called neuraminidase inhibitors (NAI)—also referred to as antivirals—attack influenza viruses, at the cellular level and block the viruses' ability to escape from cells already infected, thus preventing the infections from spreading.

These antiviral medications can also prevent the flu, which can help contain the virus in certain settings, such as family members passing the flu to one another in a household or coworkers spreading it in the workplace.

Diagnosis

Many people confuse the terms "cold" and "flu" because the illnesses share some of the same features. Both are caused by viruses that infect the respiratory tract, mainly during the winter, and both can cause symptoms such as coughing and sore throat. A cold is a minor viral infection of the nose and throat and can occur in any season. More than 200 viruses are known to cause the common cold.

It's important to know the difference between the cold and flu because each illness is treated differently. You know you have the flu when you feel as though you've been hit by a truck and experience symptoms such as high fever, severe headache, muscle and body aches and extreme tiredness, along with coughing and nasal symptoms. A cold is less severe and often includes a runny nose, sneezing and coughing. Unlike flu, colds typically don't cause fever.

Flu Symptoms

The flu causes muscle and joint pain, high fever, a deep cough, chills, fatigue and weakness that usually send you straight to bed for three to five days or longer. Afterward, cough and tiredness may persist for days or even weeks. Other symptoms include headache, eye pain and sometimes a stuffy nose and sore throat. Some strains of the flu also produce vomiting and diarrhea. Symptoms usually come on suddenly once you've been exposed to the virus.

While there is such a thing as "stomach flu," it is not caused by the influenza virus. Most people with stomach flu are infected with one of the many gastroenteritis viruses that cause temporary nausea and vomiting.

If you've been in contact with someone who has the flu and you begin to experience flu-like symptoms, chances are you have the virus. Only your health care professional can diagnose your symptoms accurately, so it's important to call for an appointment as soon as your symptoms develop to see if you're a candidate for prescription antiviral medication.

If you think you've been exposed to someone who has the flu and you begin to experience symptoms, the CDC currently recommends you stay home and keep away from others as much as possible and avoid travel, work, school or public places for at least 24 hours after your fever is gone (without the use of fever-reducing medication) except to get medical care or for other necessities.

If you become severely ill or you are in one of the groups at high risk for complications, (children younger than five, pregnant women, people of any age with certain chronic medical conditions like asthma, COPD, diabetes or heart disease, people who are immunosuppressed due to HIV infection or because they are taking immunosuppressive medications, and people over age 65), call your health care professional or seek medical treatment.

In children, warning signs necessitating emergency medical care include fast breathing or trouble breathing; bluish or gray skin color; not drinking enough fluids; severe or persistent vomiting; not waking up or not interacting; being so irritable that the child does not want to be held; and flu-like symptoms that improve but then return with fever and worsening cough.

In adults, warning signs necessitating emergency medical care include difficulty breathing or shortness of breath; pain or pressure in the chest or abdomen; sudden dizziness; confusion; severe or persistent vomiting; and flu-like symptoms that improve but then return with fever and worsening cough.

Antiviral medications can be used to treat people who are severely ill with flu. To be effective, antiviral medications should be taken within 12 to 48 hours of the onset of symptoms.

Flu Complications

Flu often develops into acute bronchitis—an inflammation of the bronchi, the air passages or tubes to the lungs. Symptoms include:

• A fever, 100 to 102 degrees Fahrenheit.
• An irritating, dry, painful cough that starts to produce small amounts of white or light yellow sputum after two or three days; at this stage the fever often recedes, and the pain from coughing diminishes. If your sputum is yellow-green or green in color, you may have a bacterial infection.

Even after the condition improves, a slight cough commonly remains for another week or two. Most cases of acute bronchitis simply represent continued inflammation from viral infection, rather than a bacterial complication. Many people benefit from short-term use of an inhaled bronchodilator such as albuterol (Accuneb, Proventil, Ventolin or ProAir).

You usually don't need antibiotics, regardless of how long your cough has lasted. However, if you have a cough for three weeks or more, you should be carefully evaluated to rule out pneumonia or bacterial bronchitis. If you are producing green secretions when you cough, you may have a bacterial infection and need antibiotics.

Pneumonia symptoms typically appear after you feel like you've just about recovered from the flu. Symptoms include:

• high fever
• shaking chills
• chest pain with each breath
• continuous hacking cough that produces thick, yellow-greenish-colored phlegm, or sputum, or sputum with blood in it
• extreme weakness and fatigue

The Flu in Children

Children are both highly likely to get the flu and the most likely to transmit it to others. In fact, studies find that:

• Children are more likely than adults to get the flu and to have complications with the illness. The flu is most serious in children under age 2.
• Families with school-age children experience more flu infections than those without because schools are ideal locations for viruses to attack and spread. On average, about one-third of family members of school-aged children are infected with the flu each year.
• Children do not have as much natural immunity to influenza as adults because they have had less lifetime exposure. Also, close contact with other children in school, home and day-care settings increases a child's risk of getting and spreading the virus.

Treatment

When you have the flu, the most important thing is rest. Plus, if you stay home, there's less risk that you'll spread the flu to other people. Flu can continue to be contagious for up to five to seven days after symptoms appear.

The following may help with flu symptoms:

• Ask your health care professional about the prescription antiviral drugs oseltamivir (Tamiflu), zanamivir (Relenza) or baloxavir marboxil (Xofluza). Antivirals attack the virus at the source and should be started within 12 to 48 hours from the time the first symptoms appear to be effective. If taken within the proper timeframe, antivirals can help you feel better faster. Tamiflu, an oral medication available in capsule or liquid form, is approved for people one year and older. Relenza, an inhaled medication, is approved for people seven years and older. Xofluza is a new drug, approved in 2018, that is given in a single oral dose to people age 12 or older. Side effects are mild and, depending on the drug, may include nausea, diarrhea, bronchitis and, less commonly, vomiting. Relenza may cause some nasal irritation.
• Drink plenty of fluids. Hot liquids may relieve the feeling of congestion and loosen phlegm.
• Take a pain reliever like acetaminophen for aches and fever. However, don't use aspirin or products containing aspirin on anyone under 19 years of age, because there is a strong link between aspirin and Reye's Syndrome, a disease that affects all body organs, particularly the brain and liver, in children.
• Take a cough suppressant for relief from a dry, hacking cough when trying to sleep. A cough that produces mucus or phlegm is not necessarily a symptom of flu, but it can be a symptom of a cold or other illness. If you are coughing up phlegm, you may have developed a secondary bacterial infection that needs to be treated by a health care professional. Don't use a suppressant if you are coughing up mucus; it's important that you get those substances out of your lungs.
• Use a humidifier, respirator or steamer in the bedroom to help ease congestion.

Because the flu is a viral infection, it cannot be treated with antibiotics. Antibiotics only kill bacteria and thus are useless against the flu. Taking antibiotics when you don't need them contributes to an important public health problem—antibiotic resistance. Some diseases that were once easily cured by antibiotics have become resistant to treatment. For example, earlier this century, antibiotics nearly eliminated dreaded bacterial diseases like tuberculosis and gonorrhea. However, years of widespread misuse have allowed "antibiotic-resistant" forms of these illnesses to become more common.

However, if your health care professional finds that you've developed a bacterial infection such as pneumonia, you will likely need antibiotics. Take the full amount of medication as prescribed, even if you start feeling better. Otherwise, the infection may return. Never stockpile antibiotics or share them with other people.

Prevention

To avoid getting the flu or to reduce its severity, the CDC now recommends all people age 6 months and older get a flu shot as soon as it is available each fall. Vaccination is especially important for people at high risk for complications from the flu, including those who are pregnant, are age 65 or older, have a chronic health problem, are health care workers or live or work around the elderly. The vaccine helps your immune system fight off the flu virus when you're exposed.

Starting in 2016, the CDC says that people who are allergic to eggs and experience only hives after eating them can get any recommended flu shot that is appropriate for someone their age. People who have severe egg allergies should get their vaccine in a medical setting supervised by a health care provider who can manage severe allergic conditions.

People with a fever should not get vaccinated without first consulting their health care professional.

The flu vaccine has been shown to be completely safe to take during pregnancy, but again, discuss this with your health care professional. The most common side effect of the vaccine is soreness at the site of the injection. Essentially everyone can receive the flu vaccine, but it is important if you have concerns to discuss these issues with your health care provider.

While the vaccine itself cannot cause the flu, you could be exposed to the flu within two weeks after vaccination, before you have time to develop antibodies or immune resistance. Then, when you get sick, you might think the vaccine caused it.

Because your immune system needs several weeks to respond to the vaccine, the best time to get vaccinated is in October or November since most flu activity occurs in January or later. Some flu seasons can last as late as May, and the 2009 H1NI flu was reported even in summer. No matter the date, it's still worth getting vaccinated any time during flu season. You start to develop some immunity from the vaccine within a few days to two weeks.

Planning Ahead: Recommendations for Flu Vaccinations

The U.S. Centers for Disease Control and Prevention (CDC) recommends that everyone 6 months and older get vaccinated against the flu, unless your health care provider says you should not. There are several types of flu vaccinations available:

• Flu shots made with inactivated (killed) flu virus are approved for use in people 6 months and older.
• A standard quadrivalent flu shot (protects against four flu strains) is made using virus grown in eggs and sold under several brands, which are approved for different age groups; some are approved for people as young as 6 months of age. Most are given in the arm with a needle.
• A quadrivalent cell-based flu shot containing virus grown in egg-free cell culture is approved for people 4 years and older.
• A standard trivalent flu shot, also manufactured using virus grown in eggs, protects against three strains of flu and is approved for people ages 5 years and older.
• A high-dose trivalent flu shot is approved for people age 65 and older.
• A trivalent flu shot made with adjuvant—an added ingredient that helps create a stronger immune response—is approved for those 65 and older.
• A recombinant quadrivalent flu vaccine that is produced without using an egg-grown vaccine virus and doesn't use chicken eggs in production; may be recommended for people age 18 and older with severe allergic reactions to any components of other flu vaccines.
• A thimerosal-free vaccine
• A nasal spray vaccine that is approved for use in anyone age 2 through 49 years. However, it should not be used in people with certain underlying medical conditions, such as pregnant women; people with a weakened immune system; and people with diabetes, heart disease or kidney liver disorders. More information about who can and can't get the nasal spray flu vaccine can be found here.

While almost everyone should get a vaccine each flu season, it is particularly important for certain groups to get vaccinated because they are at risk for serious flu-related complications or they live with or care for people at risk for developing these complications. These groups include:

• pregnant women
• children younger than age five, but especially children younger than two
• people age 65 or over
• anyone with chronic medical conditions, especially asthma or chronic bronchitis and emphysema
• anyone in a long-term care facility or nursing home
• anyone who lives with or cares for those at high risk of complications from flu, including:
  • health care workers
  • household contacts and out-of-home caregivers of children younger than 6 months
  • people within regular contact with those at risk for flu complications

If you or a family member wants to receive a flu vaccine but cannot locate a source, you can search by zip code at the following American Lung Association Web site: https://www.lung.org/lung-disease/influenza/flu-vaccine-finder/.

In addition, some public clinics offer the vaccine. Ask your health care professional for more information about restrictions and availability of the flu vaccine.

Who Should Not Be Vaccinated

There are some people who should not be vaccinated with injected influenza vaccine, according to the CDC. These include those who:

• are under 6 months of age
• have a severe allergy to chicken eggs, although your allergist can likely immunize you safely, and there are some egg-free vaccines available
• have had a severe reaction to a previous influenza vaccination
• developed Guillain-Barré syndrome within six weeks of getting an influenza vaccine
• have a fever (wait until your fever subsides)

Prescription Antiviral Medication for Flu Prevention

Prescription antiviral medications, used as an adjunct to vaccination, may be extremely helpful in preventing the onset of flu. If you have been around someone who has the flu, a doctor can prescribe antiviral medication to help prevent you from catching the virus. However, it's important to contact the doctor fast, as antiviral medication should be taken within the first 12 to 48 hours of exposure to the virus. After taking oseltamivir (Tamiflu) within 48 hours of the first appearance of flu symptoms, adults felt better 30 percent faster (within 1.3 days) than adults with the flu who did not take the medication. And children taking Tamiflu felt better 26 percent faster (within 1.5 days) than children who didn't take the medication.

According to the CDC, it's important that antiviral drugs be used early to treat people who are at risk for developing serious complications from the flu, such as the very young and the very old and people with certain high-risk medical conditions, or for people who are very sick with the flu. Other people may also be treated with antiviral drugs this season. However, most people who come down with the flu and are otherwise healthy do not need to take antiviral drugs.

Use of antivirals is dependent on availability. If Tamiflu and Relenza become in short supply, they may first be given to people who have been hospitalized or are at risk for severe complications from the flu.

Minimizing Your Risk

Here are several simple common-sense things you can do to protect yourself from the flu and to help prevent the spread of the flu virus:

• Cover your mouth and nose when you sneeze or cough and teach your children to do the same. Use tissues, not handkerchiefs, and dispose of the tissue after one use. Also, try not to touch your mouth, nose or eyes to avoid spreading germs.
• Keep your distance (at least three feet), if possible, from people who have the flu, because the virus is spread when an infected person coughs or sneezes.
• Wash your hands frequently to reduce your risk of catching a cold or flu. Ordinary soap is sufficient. If soap and water are not available, use an alcohol-based hand cleaner. Antibacterial soaps add little protection, particularly against viruses. In fact, a study suggests that although hand washing with soap reduced the number of pneumonia-related infections in children under five by 50 percent, and there was no difference in the results when antibacterial soap was used instead of regular soap.
• Avoid second-hand cigarette smoke and, if you smoke, try to quit.
• Try to maintain a healthy lifestyle to build your immunity by following a nutritious diet, getting enough sleep, drinking lots of water and minimizing stress. Eating lots of fruits and vegetables, which are rich in antioxidants and other important plant-based chemicals, may help strengthen your immune system.
• If you are sick with flu-like illness, the CDC recommends you stay home for at least 24 hours after your fever is gone (without the aid of fever-reducing medication) except to get medical care or for other necessities.

The herbal remedy echinacea gets a lot of attention for its claims to prevent colds and flu or for minimizing symptoms, if they do develop. However, most studies on this herb find no benefits when it comes to preventing either colds or flu. Studies do find, however, that using echinacea at the beginning of a cold can reduce the length and intensity of the illness. Because there are no standards or quality controls available for supplements like echinacea (including what part of the plant is used in the supplement) and some supplements may cause toxic side effects in large doses, you should always discuss natural remedies with your health care professional before taking them.

There is no evidence that large doses of vitamin C prevent or cure colds or the flu. However, several studies find that zinc lozenges may reduce the length and intensity of colds and flu. Gels and nasal sprays containing zinc recently came under fire from the U.S. Food and Drug Administration. In 2009, the FDA warned consumers not to use three zinc-containing products administered through the nose. Those three products (Zicam Cold Remedy Nasal Gel and Zicam Cold Remedy Swabs for adults and kids) may cause loss of sense of smell.

Facts to Know

1. Influenza, or the flu, is a viral disease of the respiratory tract—the nose, throat, bronchial tubes and lungs. It's similar to a cold in that both are caused by viruses that infect the respiratory tract, mainly in the winter season, and both can cause symptoms such as coughing and sore throat. A cold is a minor viral infection of the nose and throat, and its primary symptoms are nasal stuffiness, sneezing, runny nose, sore throat and cough. Influenza is more serious, and its major symptoms are high fever, severe aches and pains, cough with mucus production, tiredness and weakness.

2. The flu is highly contagious and is spread though airborne droplets of moisture produced when someone with the flu coughs or sneezes. When you breathe in these germs, you may come down with the flu, generally within one to four days of being exposed.

3. Rates of influenza infection vary among age groups and from one season to another, according to the U.S. Centers for Disease Control and Prevention (CDC).

4. Flu seasons are unpredictable, and in some years, flu outbreaks are severe. The CDC estimates that flu-related deaths in the U.S. have ranged from a low of 12,000 to a high of 56,000 from 2010 to 2014.

5. Smoking can increase your risk for the flu and complications from the flu, because smoking injures your airways and damages the cilia, tiny hair-like structures that help keep the airways clear.

6. The most serious, often life-threatening complication of the flu is pneumonia. Other complications include ear infection, bronchitis, dehydration and worsening of chronic conditions, such as congestive heart failure, asthma or diabetes. Croup and a lung disease called bronchiolitis can develop as complications in infants and young children.

7. The influenza virus changes its genetic makeup from year to year, which means that each year you're likely exposed to a new virus. That's why you can get the flu every year, and why a flu vaccine is recommended annually. Vaccines, which are made with killed or inactivated virus or viral fragments of those strains, work by forcing the immune system to make antibodies that fight circulating strains of influenza.

8. A flu vaccination is your best chance to protect yourself against the flu. You should get a seasonal flu vaccine every year because the flu vaccine is formulated to keep up with constantly changing flu viruses.

9. The nasal spray flu vaccine, FluMist Quadrivalent, is also available from your health care professional. This live-active influenza-virus vaccine is recommended for children at least age 2 and adults up to age 49. It is effective in preventing the same flu types contained in the inactive injectable versions of the flu vaccine.

10. Prescription antiviral medications, such as oseltamivir (Tamiflu) and zanamivir (Relenza), can be used to treat and prevent the flu if used within 12 to 48 hours of symptom onset or exposure to the virus.

Questions to Ask

Review the following Questions to Ask about flu/colds so you're prepared to discuss this important health issue with your health care professional.

1. Am I at high risk for catching the flu and/or developing complications from the flu?
2. Should I get a flu vaccine?
3. Are my symptoms caused by the flu or another type of infection?
4. Which medications are useful in fighting the infection I have?
5. Is it too late to take a prescription antiviral medication?
6. If antiviral medication is prescribed, what exactly will it do?
7. What are the possible side effects of the medication you are prescribing?
8. Should I avoid other medications, alcohol or certain foods while I take this medication?
9. How long will it take the antiviral medication to work?
10. How long will I feel sick with the flu?
11. How long should I stay away from others after coming down with the flu?

Key Q&A

Organizations and Support

For information and support on Flu/Colds, please see the recommended organizations and Spanish-language resources listed below.

American Academy of Family Physicians (AAFP)
Website: https://www.aafp.org
Address: P.O. Box 11210
Shawnee Mission, KS 66207
Hotline: 800-274-2237
Phone: 913-906-6000

American Lung Association (ALA)
Website: https://www.lung.org/
Address: 61 Broadway, 6th Floor
New York, NY 10006
Hotline: 1-800-LUNG-USA (1-800-586-4872)
Phone: 212-315-8700

Association for Professionals in Infection Control and Epidemiology, Inc.
Website: https://www.apic.org
Address: 1275 K Street NW, Suite 1000
Washington, DC 20005
Phone: 202-789-1890
Email: apicinfo@apic.org

Bureau of Infectious Diseases
Website: https://www.canada.ca/en/public-health/services/infectious-diseases.html
Address: Public Health Agency of Canada
130 Colonnade Road, A.L. 6501H
Ottawa, Canada, -Intl- K1A 0K9
Email: info@hc-sc.gc.ca

CDC National Immunization Information Hotline
Website: https://www.cdc.gov/vaccines
Address: NIP Public Inquiries, Mailstop E-05
1600 Clifton Road, NE
Atlanta, GA 30333
Hotline: 1-800-CDC-INFO (1-800-232-4636)
Email: cdcinfo@cdc.gov

Center for Infectious Diseases Research and Policy (University of Minnesota)
Website: https://www.cidrap.umn.edu
Address: University of Minnesota, Academic Health Center
420 Delaware Street SE, MMC 263
Minneapolis, MN 55455
Phone: 612-626-6770
Email: cidrap@umn.edu

Infectious Diseases Society of America
Website: https://www.idsociety.org
Address: 1300 Wilson Blvd., Suite 300
Arlington, VA 22209
Phone: 703-299-0200
Email: info@idsociety.org

International Society for Infectious Diseases
Website: https://www.isid.org/
Address: 1330 Beacon Street, Suite 228
Brookline, MA 02446
Phone: 617-277-0551
Email: info@isid.org

National Foundation for Infectious Diseases
Website: https://www.nfid.org
Address: 4733 Bethesda Avenue, Suite 750
Bethesda, MD 20814
Phone: 301-656-0003
Email: info@nfid.org

Spanish-language resources

Centers for Disease Control and Prevention: Influenza
Website: https://espanol.cdc.gov/enes/flu/index.htm
Address: Centers for Disease Control and Prevention
1600 Clifton Rd
Atlanta, GA 30333
Hotline: 1-800-232-4636
Email: cdcinfo@cdc.gov

Medline Plus: Flu
Website: https://www.nlm.nih.gov/medlineplus/spanish/flu.html
Address: Customer Service
8600 Rockville Pike
Bethesda, MD 20894
Email: custserv@nlm.nih.gov