Should you get the flu shot? What to know about the 2019-20 flu season

With the first day of fall just around the corner, medical professionals are issuing a serious warning as this year’s flu season arrives: get your flu shot.

“The flu shot is incredibly important because it reduces your risk of contracting the flu,” Michelle Lin, an emergency room doctor, and professor of emergency medicine at Mount Sinai in New York City, told Fox News.

“It also reduces your risk for complications and passing it to other people, especially pregnant women, young children and the elderly,” who are more susceptible to the virus, she added.


Here’s what you need to know about the 2019-20 flu season.

How long does it take for the vaccine to take effect?

Roughly two weeks, Lin said, recommending patients receive the vaccine as soon as possible. During this time, your body is developing antibodies to protect you against the virus. Lin said she and other health professionals have recommended patients receive the vaccine before the end of October, as flu season typically peaks during the cold, dry weather between December and February.

But receiving the vaccine anytime during the season is “better late than never,” Lin noted.

How many strains of flu does the vaccine protect against?

Flu vaccines typically protect against three or four viruses, the Centers for Disease Control and Prevention (CDC) says.

“There are many different flu viruses and they are constantly changing. The composition of U.S. flu vaccines is reviewed annually and updated as needed to match circulating flu viruses,” per the federal health agency.

Health professionals are urging citizens to get their flu shot.

Looking at weather patterns and using statistics and other data, health professionals make an educated guess of which strains will be the most contagious during each flu season, Lin explained.

That said, Mirella Salvatore, an infectious disease specialist at Weill Cornell Medicine and NewYork-Presbyterian, told The New York Times last year that even when vaccines do not match circulating strains, “they seem to prevent severe disease, and studies show that unmatched vaccines can still avert millions of hospitalizations.”

This year’s three-component vaccine protects against:

  •  A/Brisbane/02/2018 (H1N1)pdm09-like virus
  • A/Kansas/14/2017 (H3N2)-like virus
  • B/Colorado/06/2017-like (Victoria lineage) virus

Also available are the quadrivalent, or four-component, vaccines. These vaccines “protect against a second lineage of B viruses,” according to the CDC. In addition to the three viruses in the three-component vaccines, the quad vaccines also protect against the B/Phuket/3073/2013-like (Yamagata lineage) virus.

“Last season’s vaccine was only 29 percent effective because of a surge in H3N2 virus late in the season, which was not included in the vaccine, so all versions of this year’s vaccine include an H3N2 strain,” Lin said. “The quadrivalent vaccine (protects against 4 viruses) is now approved for children as young as 6 months, expanding on the previous lower age limit of 5 years.”

But how do you know which vaccine you’re receiving? Most are quadrivalent, Lin said.

Trivalent, three-component vaccines, “that are higher dose or elicit a stronger immune response may be recommended for some people age 65 or older,” she continued. “The nasal spray is quadrivalent and approved for those age 2-49 years, but not recommended for pregnant persons or those with chronic conditions.”

What is a common misconception about the flu vaccine?

While there are many misconceptions about the flu vaccine, “the most common one we hear is that it gives people the flu,” Lin said.

While reactions to the flu shot may include a low-grade fever or muscle aches, the vaccine cannot cause the flu virus. The shot is either made with a virus that has been “killed” or “inactivated” or made with “only a single gene from a flu virus (as opposed to the full virus) in order to produce an immune response without causing infection,” the CDC says.


How severe will this year’s flu season be?

It’s hard to predict. But the flu season in Australia, in particular, can give experts an idea of how severe the flu season in the U.S. might be — as the U.S. tends to echo Australia in both severity and strains.

“While it’s too early to say for sure, Southern Hemisphere flu season, which just ended and was more severe than usual, can sometimes mirror the upcoming Northern Hemisphere flu season, so it’s best to prepare,” Lin said.