What is influenza, and what is H3N2?
Influenza is the name of a very large and diverse family of viruses that infect the human respiratory tract. The disease caused by those viruses is also called influenza, and it afflicts roughly 60 million Americans annually, particularly in the winter months (hence the common name “seasonal flu”). There’s a brand-new strain of influenza called H3N2, a variant of a common subtype of influenza, and it’s different from the viruses that typically cause seasonal flu. The new strain is now commonly known as “swine flu” or just “H3N2.”
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How serious is influenza?
For the most part, seasonal influenza and H3N2 influenza do not pose serious health risks to individuals. More than 99 percent of all infections cause fairly mild symptoms and get better on their own. Severe illnesses and deaths are very rare. (Less than 1 percent and less than 0.1 percent, respectively.) H3N2 is generally less severe than seasonal flu.
How does influenza spread?
Both seasonal and H3N2 influenza spread person-to-person. H3N2 does not spread via animals or food (e.g., pork). An infected person can transmit influenza by coughing or sneezing, sending virus-containing droplets onto nearby people and surfaces. The virus can then survive on surfaces up to eight hours.
What are the symptoms?
The symptoms of influenza are usually more severe than the symptoms of a common cold. Symptoms typically develop one day to seven days after exposure, and can last from a few days to two weeks. They may include any or all of the following:
- Fever (usually 100°F or warmer, lasting for several days)
- Body aches or muscle aches
- Sore throat
- Runny or stuffy nose
- Nausea and sometimes vomiting
Uh-oh. I think I have influenza. How can I tell whether I have H3N2 or seasonal influenza?
The only way to distinguish between the two viruses is to do a special test, which can take several days and is not 100 percent reliable. Fortunately, for the vast majority of patients, it doesn’t matter. We treat both illnesses the same way.
But I still need to be tested, right?
Not necessarily. Testing for influenza isn’t always helpful, particularly during an outbreak. If you’ve got the symptoms, we can be reasonably sure you’ve got the disease, and we’ll treat you accordingly. In most scenarios, it’s better for you to stay at home and rest, rather than come to the office for a useless test. However, there are a couple of exceptions. If you think you’ve been exposed to swine flu, or are concerned that your symptoms might signal something other than the flu, then you should get tested, especially if your symptoms occur outside of flu season. Why? It won’t affect your treatment plan, but it’s an important act of social responsibility that will help the CDC track pandemics and plan future vaccines.
So what should I do if I get sick?
Whether you’ve got H3N2 or seasonal flu, there’s really no substitute for old-school, common-sense treatments. Get lots of rest and drink plenty of fluids. Avoid alcohol and tobacco. Take acetaminophen (Tylenol) and/or ibuprofen (Motrin, Advil) for fever and body aches, but avoid aspirin if you’re under the age of 19. You should start feeling better within a few days. If you are at risk for complications of influenza (see below), or if your symptoms are clearly getting worse, call our office and ask to speak with someone on our medical staff for more advice.
How can I prevent making other people sick? When can I go back to work/school?
Wash your hands frequently, cough and sneeze into your arm (not your hands) and throw out tissues immediately after use. Most importantly, stay home. Don’t return to work or school until you have had a normal body temperature (under 100°F without taking a fever-lowering medication such as Advil or Tylenol) for at least 24 hours. And please don’t come to our office without calling first!
How long will I be contagious?
You’re contagious from the day before you develop symptoms until 24 hours after your fever breaks.
Do I need to wear a mask while I’m sick?
No, not if you stay home and can remain at least six feet away from other people. However, if you simply must be in close contact with others (e.g., for an airplane flight), then consider wearing a surgical mask. This is especially important if you will be in contact with people at risk for complications of influenza (see below). For example, sick mothers who are nursing infants should strongly consider wearing a mask for the duration of the illness.
Do I need an antiviral medication (e.g. Tamiflu)?
Usually not. Most people with influenza will recover completely without medication. Drugs like Tamiflu can help shorten the duration of symptoms and help lessen the severity of symptoms by a day or so, but they won’t cure and won’t reliably prevent influenza. In fact, overzealous use of these drugs has the potential to contribute to the emergence of resistant super-viruses. However, if you have influenza and you are at risk for complications (see below), you should receive antiviral medication. In that case, please call our office to speak with someone on our medical staff as soon as possible, since antiviral the drugs work best if taken within two days of becoming ill.
How do I know if I’m at risk for complications of influenza?
You are at increased risk for complications if:
- You are pregnant
- You have a chronic medical condition, such as diabetes, obesity, heart disease, kidney disease, liver disease, asthma, emphysema, cancer, HIV, etc.
- You are age 65 or older
- You are younger than age 5
- You are younger than age 19 and are receiving long-term aspirin therapy
If you fall into any of these categories and are feeling sick, or have been exposed to someone with a confirmed case of influenza, please call our office and ask to speak to a medical staff member for further guidance.
When should I go to an emergency room?
You should go directly to an emergency room for further evaluation and treatment if you have any of the following symptoms:
- Difficulty breathing
- Pain or pressure in the chest or abdomen
- Bluish skin color
- Confusion or sudden dizziness
- Persistent or severe vomiting
Yuck. I definitely don’t want to get influenza. How can I protect myself from getting sick?
- Wash hands with soap and water or hand sanitizer frequently. Be aware of touching common surfaces like doorknobs, faucets, phones, keyboards, etc., and wash hands afterward. Avoid touching your eyes, nose, or mouth unless you have clean hands.
- Try to stay at least six feet away from people who appear ill, and avoid sharing food, drinks, toothbrushes, etc. during an outbreak. Wearing a mask is not necessary.
- Keep your immune system healthy. Get plenty of sleep (8 hours a night is ideal), drink plenty of water, and eat plenty of fruits and vegetables. Avoid alcohol, tobacco and other unhealthy vices!
- Get vaccinated! (See below for details.)
I’ve been exposed to someone with influenza! Will I get sick?
There’s no way to know for sure, but if you’ve followed the guidelines above, and especially if you’ve received the appropriate vaccinations, you’ve got a very good chance of remaining healthy. On the other hand, if you are in the at-risk group described above, you should consider taking an antiviral medication like Tamiflu to further reduce your chances. Please call our office to discuss this with someone on our medical staff.
Should I get a seasonal flu shot?
Ideally, yes, you should! Everyone stands to benefit from getting a seasonal flu shot, but it’s especially important if you’re pregnant (or planning to become pregnant), over the age of 50, have any sort of chronic medical condition, or are caring for someone who is at risk for complications of influenza.
Are flu vaccines safe?
Generally, yes. Influenza vaccines, including the H3N2 vaccine, have been studied carefully and are generally very safe. However, if you’ve had an allergic reaction (or other bad reaction) to a vaccine in the past, be sure to let us know before you receive any vaccine.
Where can I learn more?
The One Medical blog is published by One Medical, an innovative primary care practice with offices in Boston, Chicago, Los Angeles, New York, Phoenix, the San Francisco Bay Area, Seattle, and Washington, DC.
Any general advice posted on our blog, website, or app is for informational purposes only and is not intended to replace or substitute for any medical or other advice. The One Medical Group entities and 1Life Healthcare, Inc. make no representations or warranties and expressly disclaim any and all liability concerning any treatment, action by, or effect on any person following the general information offered or provided within or through the blog, website, or app. If you have specific concerns or a situation arises in which you require medical advice, you should consult with an appropriately trained and qualified medical services provider.