Influenza A Treatment and Medications

Cold and flu aren’t the same. Many people can get through a cold without serious problems, but unlike the common cold, influenza puts hundreds of thousands of people in the hospital every year. The bug responsible for the majority of flu cases is the influenza A virus, and it’s a potentially serious infection.

What is influenza A?

Influenza A is among the most common infectious diseases among humans and is responsible for periodic global flu pandemics, making the virus nothing less than a major global public health threat.

Influenza is a highly contagious viral infection of the nose, throat, and lungs and is easily spread from person to person through water droplets and aerosols. Transmission of influenza is primarily through coughs, sneezes, and talking, but the virus can easily be picked up from contaminated surfaces such as tables and money.

Each year, between 9 and 45 million people in the United States contract the flu, mostly during seasonal epidemics when the virus spreads throughout the population. About three in four of these infections are caused by influenza A.

Influenza A represents one of four types of influenza virus—A, B, C, and D—but only types A, B, and C can infect people. However, type A influenza is the powerhouse version; 75% of human flu cases are influenza A infections and the remainder are caused by the influenza B virus. Influenza C virus infections are rare and comparatively mild infections.

Influenza A, however, is the influenza virus responsible for global influenza pandemics. Some of the deadliest strains of the flu virus, such as avian flu, are subtypes of influenza A. Unlike the influenza B virus, which only infects humans, influenza A infects both humans and animals. Sometimes, influenza A strains, such as swine flu, cross over into humans, where they can set off an epidemic. Other strains of influenza A rarely cross from animals to humans, but when they do—in cases such as avian influenza (bird flu)—they can be deadly.

Influenza A subtypes are named for two principal proteins that stick out of their outer envelope: hemagglutinin and neuraminidase. These spike-like proteins help the virus attach to human cells as well as break into and out of cells. There are 18 different types of hemagglutinin and 11 different types of neuraminidase found in influenza A viruses, so each subtype is named from the number of each of these proteins. For instance, the H1N1 virus, or swine flu, is the most common subtype of influenza A virus that infects people.

Fortunately, most influenza A infections resolve without treatment in five to seven days. Some people, however, are prone to potentially life-threatening complications that may require hospitalization. The most common and most dangerous is pneumonia, either viral or bacterial. Other serious complications include ear infections, heart problems, bronchitis, myocarditis (swelling of the heart), or Reye’s syndrome. An influenza virus infection could also worsen existing conditions such as congestive heart failure.

Symptoms of influenza A infection commonly include:

• Fever

• Chills

• Cough

• Sore throat

• Body aches

• Headache

• Fatigue

• Nasal congestion

• Swollen, itchy, or watery eyes

It is not uncommon to experience nausea, vomiting, or diarrhea with a flu infection.

Flu, however, can turn into a severe disease. Flu symptoms that require immediate medical care include:

• High fever for several days

• Difficulty breathing when at rest or during mild exertion

• Blue skin (cyanosis)

• Rapid breathing

• Severe vomiting

• Confusion or disorientation

• Fast heartbeat

• Low blood pressure

• Chest pain

Another warning sign is when symptoms improve for a bit and then get worse. This could mean a secondary pneumonia infection has set in.

How is influenza A diagnosed?

Most flu cases are diagnosed from the symptoms, especially when seasonal influenza is going around. Patients at risk for complications, however, will have their blood tested for influenza A antibodies or genetic material to confirm the symptoms. These tests are rapidly completed, usually in about 30 minutes, so high-risk patients can begin treatment on antiviral medications. Other tests include rapid influenza diagnostic tests (RIDTs) and nasal/mouth swabs.

Risk factors for flu complications include:

• Age (older than 65 or younger than 2)

• Asthma

• Cancer,

• Heart disease

• Chronic lung, kidney, or liver disease

• Pregnancy

• Stroke

• Obesity

• Cystic fibrosis

• Diabetes

Children and teens taking aspirin or similar drugs, children with neurological disorders, and patients in nursing homes also have a higher risk of complications.

For hospitalized high-risk patients, the final diagnosis will be determined by a polymerase chain reaction (PCR) test that will identify genetic material unique to the virus. Chest X-rays, CT scans, and other testing may be required if the doctor is worried about complications.

Influenza A treatment options

The good news is that most influenza A infections run their course for a few days without requiring treatment other than a few days of rest and some supportive care. Influenza A, however, can be a serious respiratory illness, so some cases will require antiviral medications or hospitalization.

Vaccination

Seasonal flu vaccines produce immunity against two different strains of influenza A. There are, however, many other strains of influenza A out there, so the influenza vaccine will not provide immunity against these different strains or different influenza types. Also, the influenza A virus constantly mutates, so influenza immunity is always a moving target, even during a single influenza season. For this reason, historically, vaccination prevents flu infections in only 19% to 60% of people receiving the flu shot, according to the Centers for Disease Control and Prevention (CDC). On average, though, one out of two people given a flu shot will avoid seasonal flu. The CDC and almost all healthcare providers across the board recommend that everyone six months old and older get a flu vaccine.

Medications

To handle the aches, coughing, sniffles, and fever, over-the-counter medications that relieve those and other symptoms are enough to help people through an influenza A infection.

Hospitalization

Influenza A can become a serious health-threatening condition. Over the last 10 years, data from the CDC has shown that the hospitalization rate has varied from as low as 140,000 to as high as 810,000. Treatment will consist of monitoring, supportive care, oxygen, antiviral medications to fight the flu virus, antibiotics to prevent bacterial pneumonia, and, if necessary, mechanical ventilation.

Influenza A medications

Influenza A is primarily treated with bed rest, fluid intake, and symptom relief. Fortunately, a few days of bed rest will get most people past the worst part. The best treatment, however, is prevention, which is why healthcare providers nearly unanimously advise getting a flu vaccination at the start of flu season. Flu vaccines, however, are not 100% effective, so some people will still get the flu and require symptom relief medications or, in severe cases, antiviral drugs.

Vaccines

Flu vaccines are widely available and inexpensive. There are many influenza strains, so each year’s influenza vaccine targets the strains believed most likely to cause an epidemic in that year. Trivalent vaccines produce immunity against two influenza A strains and one influenza B strain. Quadrivalent vaccines provide immunity against two influenza A strains and two influenza B strains. Both trivalent and quadrivalent vaccines target the same two influenza A strains. H1N1 influenza, or swine flu, is usually one of the strains targeted in the annual vaccine. Immunity develops in about two weeks after a flu shot.

Symptom relief medications

Several over-the-counter medications can be used to relieve flu symptoms. None of these medications fight off the virus, but they make life more tolerable as the body’s immune system clears the infection. They will include ingredients such as:

• Analgesics such as acetaminophen or non-steroidal anti-inflammatory drugs (NSAIDs) reduce muscle aches, headaches, and fever.

• Antitussives (cough medicine) such as dextromethorphan relieve cough.

• Nasal decongestants such as pheniramine reduce swelling in the nasal passages.

• Antihistamines such as phenylephrine or pseudoephedrine reduce nasal drip and watery eyes.

• Expectorants such as guaifenesin loosen mucus in the air passages.

Most over-the-counter commercial “flu” medications combine two or more of these types of drugs.

Antiviral medications

Antiviral medications directly target the virus itself, interfering with its ability to infect cells in the body. These include Tamiflu (oseltamivir), Rapivab (peramivir), Relenza (zanamivir), and Xofluza (baloxavir marboxil). They are highly effective at rolling back an influenza A infection if they are given within a day or two after symptoms first appear. At later stages, more than 36 hours after the first appearance of symptoms, these antiviral drugs are used to prevent complications or bring a severe infection under control. Both Tamiflu and Relenza can also prevent an influenza A infection and are prescribed to the highest-risk patients to take throughout the influenza season, but they are not a substitute for the flu vaccine.

What is the best medication for the flu?

If you ask most medical professionals what flu medication they would recommend, most would tell you to get a flu vaccination before the start of flu season. Otherwise, the “best” medication for most cases of flu is to rest and drink fluids. However, people at risk for complications may require antiviral medications early in the infection. Antivirals may not be appropriate for every patient.

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Best medications for influenza A