H3N2: What You Need to Know About This Year’s Flu

In some parts of the country, the virus has struck hard. Here, we break down how to prevent its spread and lessen symptoms.

For many Americans, 2018 is off to a buggy start.

That’s because about 6 percent of those seeing a doctor or other healthcare provider have verified influenza symptoms, according to a Centers for Disease Control and Prevention’s flu report released January 19. What’s more, the total seasonal lab-confirmed cases hit 74,562; 30 children have died of the influenza virus; and outbreaks have been reported across the country.

To parse these numbers, and for tips on how to prevent the spread of the flu and what to do to alleviate symptoms, we spoke with Dr. Judy Tung and Dr. Keith Roach, associate professors of medicine at Weill Cornell Medicine.

The flu outbreak seems particularly deadly this year. Why is that?
Dr. Tung: The predominant strain of influenza this year appears to be H3N2, which is historically associated with a greater chance of hospitalization and death, especially for the young and the elderly. Additionally, mutations in the virus produce high variability in the effectiveness of vaccines, and this year’s vaccine appears to be less effective.

Who is at high risk for complications from the flu?
Dr. Tung: Populations at higher risk for complications include children under the age of 5 (with those under 2 especially at risk); adults over the age of 65; residents of nursing homes or chronic care facilities; pregnant women; individuals with chronic conditions such as asthma or COPD, diabetes, liver or kidney disease, and cardiovascular disease, especially congestive heart failure; plus patients whose immune systems are compromised, including those with HIV, those who have active cancers, and those who are on immunosuppressant medications.

Is it too late to get the flu shot?
Dr. Roach: No, it’s not. The flu season lasts until April or May, and the flu shot takes about two weeks to provide protection, so it is certainly worthwhile to get vaccinated through February and March. Still, the sooner the better. Also, remember you are protecting others, including those who cannot get the flu shot or in whom it doesn’t work well because of medical problems or immune system disease.

Is there anyone who should not get the flu shot?
Dr. Tung: Because the vaccine is produced in embryonated chicken eggs, individuals with a severe allergy to eggs should be cautioned before receiving the vaccine. Patients who have also developed Guillain-Barre syndrome following prior influenza vaccination should be cautioned.


“The flu season lasts until April or May, and the flu shot takes about two weeks to provide protection, so it is certainly worthwhile to get vaccinated through February and March.”

— Dr. Keith Roach


Once I’ve received the shot, what else can I do to prevent the flu?
Dr. Roach: The best bet is to avoid people who are sick. Since that isn’t completely possible, frequent hand-washing and being careful not to touch your face and mouth except after hand-washing is important. No supplements have been shown to protect against getting flu.

How can I tell the difference between the flu and the common cold?
Dr. Roach: The flu has sudden onset of fever, muscle aches (often severe), a cough, and maybe a runny nose. A cold does not have significant fever usually and lacks the severe muscle aches. A cold does not come on so quickly, and it causes a sore throat, runny nose, sneezing, and a cough.

If it turns out I have the flu, should I see a doctor?
Dr. Tung: If you suspect that you have the flu, you should consult with a doctor as soon as possible. There is a window of opportunity, typically two days, for optimal benefit from antiviral medications such as Tamiflu, so a swift decision on whether this treatment is indicated should be made. Even if supportive care is all that will be recommended, guidance on which over-the-counter remedies to take (to avoid unnecessary medicines) should be made with your healthcare provider. A phone consultation is a good place to start, as it is advisable to stay at home to minimize the spread of the virus if safe and possible.

How effective is Tamiflu in treating flu symptoms?
Dr. Roach: Tamiflu really works, although it certainly isn’t perfect. Most studies show it speeds up getting better by half a day to two days. It does seem to reduce the dreaded complications of flu, including hospitalization and pneumonia. It should be given as soon as possible after onset of symptoms.

What should I do if my symptoms are not clearing up?
Dr. Tung: Most patients will gradually improve within a week, although some can have persistent fatigue for several weeks. If there is progression of high temperatures, shortness of breath, chest pain, lethargy, or severe weakness, you should seek medical attention immediately.

Any other tips for how to fight the flu?
Dr. Tung: Support your immune system during the illness with adequate rest, good nutrition, and generous hydration while fighting the flu. Treating high fevers with over-the-counter medications will decrease your risk of inadvertent dehydration. Hand hygiene will minimize the spread in the office and the household.

For more information on how to protect yourself and your family from the flu this season, visit here.

Dr. Judy Tung is section chief of ambulatory internal medicine and chair of the department of medicine at NewYork-Presbyterian Lower Manhattan Hospital and an associate professor of clinical medicine at Weill Cornell Medicine.

Dr. Keith Roach is an associate professor of clinical medicine in the division of general medicine at Weill Cornell Medicine and an internist at NewYork-Presbyterian/Weill Cornell Medical Center.