Should you get the flu shot?

We hear the recommendations around this time every year – it’s flu season and we should get a vaccination, we’re told.

Officials at the Centers for Disease Control and Prevention say that, with a few exceptions, everyone 6 months old and older should get an annual flu vaccination.

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They are offered at work, at pharmacies and even at drive-thru events. But, if you are a healthy adult, do you really need to get the shot?

What about your children? Should they get one?

Vaccine manufacturers are on track to make as many as 176 million doses of flu vaccine for the 2016-2017 flu season, according to the CDC. Enough for Americans looking to get the shot during an average flu season (in the 2014-2015 season,  148.1 million Americans were vaccinated).

Included in that number, is 14 million doses of a flu vaccine delivered via a nasal spray. The CDC announced recently that they are not recommending doctors give the nasal spray version – used primarily to give the vaccine to children – because studies have shown a decline in effectiveness.

Some recent studies are questioning the need for an annual flu vaccination delivered by any means.

A study headed by Dr. Edward Belongia of the Marshfield (Wisc.) Clinic Research Foundation, reported that children who had been vaccinated annually for at least five years were more likely to contract the flu than children who were only vaccinated in the flu season in which the study was conducted.

"The vaccine was significantly more effective … if they had not been vaccinated in the previous five years," Belongia, an epidemiologist, said in an interview with STAT.com.

Here’s a look at what researchers are finding.

First, how do vaccines work?

Vaccines work to spur your body to create antibodies to fight disease. In the case of influenza, the CDC explains the flu vaccine this way:

“Flu vaccines cause antibodies to develop in the body about two weeks after vaccination. These antibodies provide protection against infection with the viruses that are in the vaccine. The seasonal flu vaccine protects against the influenza viruses that research indicates will be most common during the upcoming season.

“Traditional flu vaccines (called "trivalent" vaccines) are made to protect against three flu viruses; an influenza A (H1N1) virus, an influenza A (H3N2) virus, and an influenza B virus. There are also flu vaccines made to protect against four flu viruses (called "quadrivalent" vaccines). These vaccines protect against the same viruses as the trivalent vaccine and an additional B virus.”

So, how would having a vaccination each year cause the next year’s vaccine to be less effective?

How yearly vaccines can cause subsequent vaccines to be less effective involves the components that make up the shot, according to the STAT.com story.

Scientists believe that when a component of the influenza vaccine does not change from year to year, the antibodies made from the vaccine from year one can neutralize some of the antibodies spurred by the shot in subsequent years.

That neutralization of subsequent antibodies happens before the body can trigger a full immune response to the vaccine. The immune response takes about two weeks to fully develop.

If you know getting the vaccine in successive years can make it less effective, why not skip it?

You don’t want to skip the vaccine because each year’s shot provides protection against up to three or four types of the virus. Getting any protection against the flu is a good thing.

Each year, vaccine manufacturers include protection in the vaccines for the strains of virus they believe are most likely to be active in that year.

If you do get a component that you got last year and it blocks some effectiveness of the current vaccine, you are still better off by having the protection of the other components.

Vaccine researchers stress they are not suggesting people stop taking the yearly vaccine – at least not anytime soon. They are continuing to evaluate the need for yearly vaccinations, according to Dr. Danuta Skowronski, a flu expert at British Columbia’s Center for Disease Control in Vancouver, British Columbia.

“For me anyway, these repeat vaccine effects are among the most important developments in influenza vaccinology of the past decade,” Skowronski told STAT.com.

Cox Media Group