What you need to know about the flu this year

Currently, 29 states and New York City are reporting high levels of influenza-like-illness (ILI), and another nine states are reporting moderate levels of ILI. This season, 18 children have died from flu-associated deaths.

Related: Flu season in full swing; could get worse

Influenza is a tiny frequently mutating package of genetic material (RNA) surrounded by an envelope.

Influenza A is a more severe type than B, and H3N2 refers to proteins on the envelope. (H)emagglutinin allows the virus to attach to your cell, and (N)euraminidase allows it to cleave and attach to another cell.

The severity of flu seasons vary, based on the type of flu. This year's predominant flu (76 percent) is very similar to a type that caused a severe season in 2003-2004, when the flu shot wasn't a good match and there were more than 40,000 associated deaths.

What is happening now?
So far, more than 15,000 cases have been reported, with more than 2,000 hospitalizations last week alone.

The number of unreported cases is likely at least three or four times that amount. There is widespread activity in 41 states, and18 children have died. Most of the severe cases are due to secondary complications (the flu weakens your immune response) including pneumonia, bronchitis, sinusitis.

Can I still get a flu shot?
This year's flu shot is a good match, which means it will be effective more than 60 percent of the time. The U.S. Centers for Disease Control and Prevention has ensured a supply of 135 million doses, most of which have been distributed, and physicians such as myself still have a good supply. I am still encouraging people to get their shot, since it takes about 3 weeks to generate immunity, and the peak of the season is likely still at least three weeks away.

Who should get a flu shot?
The CDC recommends that everyone over the age of 6 months get a flu shot. This is in order to create a herd immunity, decreasing the amount of circulating flu virus, which protects those most at risk, the very young, the very old, pregnant women, and those with chronic illness.

How do I know if I have the flu?
Most clinicians make the diagnosis clinically, though we can use a nasal swab to test for the flu if we aren’t sure, and the test is approximately 60 percent accurate. (Rapid flu test gives immediate results, whereas a culture takes 48 hours) . Influenza-like illness (ILI; a clinical diagnosis) includes symptoms of fever, cough, sore throat, fatigue, nasal congestion and muscle aches.

What should I do if I have the flu?
In cases that are particularly risky (for example, chronic illnesses, asthma) it makes sense to consider a course of Tamiflu within 48-72 hours after the onset of symptoms to reduce severity. If you are sick, you should stay home from school and/or work. Wash your hands frequently, and avoid sneezing and coughing in public areas if possible. Influenza is a respiratory virus that can spread through the air as well as by touch (fomites), where it can live for up to a day.

When will flu season peak?
This year’s flu is happening early, which is characteristic of this strain. The rate of ILI is likely to remain high this year for awhile. We haven't seen anything this bad since 2003-2004. The difference is that this year we have a vaccine available that matches the strain. Expect this year’s flu season to peak at the end of this month or next.