Influenza mutations make difference in how it's prevented

Influenza mutations make difference in how it's prevented

MEMPHIS, TN (WMC) - With flu season well underway, it's time to face facts: this virus still means business. Centers for Disease Control and Prevention (CDC) says that although the number of flu cases nationally has decreased, the United States as a whole is at an elevated risk for the disease.

Despite there being a variety of flu vaccines, viruses like the flu can be tricky pests. Though the flu shot targets four different strains of the flu, health officials believe one of the strains mutated, or changed its genetic code, which can make a huge difference in how it's treated.

Every year, scientists produce a vaccine that corresponds to the virus that's going around. They can track the viruses that move around the world and visualize it similar to a weather map.

There are different kinds of flu vaccines, but the most common is the inactivated flu shot, which is made up of pieces of flu viruses, according to CDC.

"At any given time, there are three flu strains circulating in humans, two As and a B, which, itself, circulates in two forms. The As are usually H3N2 and H1N1," explained Paul Thomas, Ph.D, an associate member in the Immunology Department at St. Jude Children's Research Hospital.

While Dr. Thomas says there was a substantial change in the H1N1 virus in 2009, the same H3N2 virus has been with us since 1968.

According to CDC, flu viruses are split up into three types: A, B, and C. The two that humans have to worry about the most are A and B.

Scientists across the globe can see the viruses coming like a storm, and can often pinpoint which strain, or strains, are on their way in. But, like weathercasters, they don't always get it right. For example, according to CDC, the H1N1 strain that circulated during the infamous swine flu pandemic in 2009 was completely different from previously known H1N1 strains.

Additionally, scientists need about eight months to make the vaccines. But in eight months, the viruses circulating around the world can start to change, making them look different from the viruses used to make the vaccines.

"The H3N2 virus circulating in nature started drifting and started moving away from the reference strain," explained Dr. Thomas. "So what's circulating in humans is somewhat different from what was decided eight months ago."

Basically, the human population itself puts a lot of pressure on the virus to change. The virus makes on-purpose "mistakes" when it shapes what the outside of its shell looks like, and then your body can't recognize the virus very well. That is why you might still get the flu even after getting a flu shot. If your body can't identify the flu virus, then it won't attack it.

Most of the time, your body recognizes the flu virus after getting the flu shot because it makes antibodies, or beacons, that attach to viruses and recruit disease-killing cells to attack invaders. When you get the flu shot, the pieces of the flu virus in the shot cause your body to make these antibodies because it thinks that it's being infected. Then, when your body is infected with a live flu virus, it's already primed and ready to go.

Think of the virus and an antibody like a lock and key. When the antibodies are made against the viruses in the vaccine, the viruses and antibodies fit together perfectly. But, when the virus mutates, the antibody can't quite grasp onto the virus, causing you to get sick.

The good news is that Dr. Thomas says although the H3N2 strain has mutated, the H1N1 strain and the B strains, which the vaccine protects against, are still matched and circulating. Plus, although the H3N2 is the prevalent strain this year and the vaccine isn't completely matched to the virus that is circulating, it's still not ineffective.

"There's no reason not to get the vaccine," affirmed Dr. Thomas.

Though you may still get sick with the flu, getting your flu shot could protect you from getting a very serious form of the virus. If you don't get the shot at all, then your body won't be primed to look for any of the three flu types. When the virus hits you, your body will waste precious fighting time building up antibodies when it could be tackling the virus.

Despite Dr. Thomas' warning, not everyone should get the flu shot.

CDC provides a list of people who should not get the flu shot or the flu mist. You're encouraged to talk to your doctor or pharmacist about any pre-existing conditions or allergies you have that may prevent you from getting the shot.

Remember, the flu shot does take two full weeks to become fully effective. If you are exposed to the flu before that time, then the flu may hit you harder than if you were exposed after your body had time to build its antibody army.

"There's no way you can get the flu from the flu shot," said Dr. Thomas. "From the flu mist, you can get symptoms because it's a live virus, but you won't get the full flu. You might get some nasal irritation."

With that being said, common side effects of the shot are flu-like symptoms like body aches and a low-grade fever. Those are actually signs that your body is working. Your body heats up and produces fever in an effort to kill viruses by heat shock, and the aches are signs of antibodies building up.

"Flu symptoms after the shot should only last 24 hours or so," said Dr. Thomas. "Symptoms from the flu shot would only be a tiny percent of what the flu would be."

Thomas added that if you have symptoms for longer, you might have something else, "In a big city, the number of people that are going to get a cold is not zero." He also affirms that "the flu is definitely respiratory." If you feel queasy after getting the flu shot, then you might have another illness.

Of course, if you don't feel well immediately after getting the shot or if you aren't feeling well for a few days afterward, you should call a doctor.

Don't worry if you feel a little under the weather right after getting a shot. That could mean that your body is preparing for battle. And if this year's flu is as bad as health officials say it is, then it's going to be one heck of a war.

For more information about the flu and the flu shot, please visit the CDC flu website here.

To take a quiz to find out how much you know about the flu, click here.

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