Do Flu Shots Work?

This year’s flu season is particularly bad—and the flu vaccine isn’t stemming the spread of flu. So, do flu shots work?

do flu shots work

Do flu shots work? Despite the influenza outbreak of winter 2017-18, experts still advise a flu vaccination.

© Seanlockephotography |

If you had the flu vaccine this year, you may be expecting to get through flu season with just the odd sniffle here and there. But that might not be the case. In December, the Centers for Disease Control and Prevention (CDC) reported that flu activity had increased sharply in the United States. The CDC’s surveillance map for the week ending Dec. 30, 2017 shows that 46 states are now reporting widespread illness. CDC data shows that the proportion of flu-related outpatient visits in December was 5.2 percent (above the national baseline of 2.2 percent), and hospitalization for flu is soaring among young children and seniors. The outbreak has a lot of people asking, “Do flu shots work?”

In this current flu season, at least 106 people—including 13 children—are thought to have died from flu through mid-December. In California alone, 29 have died—an “unofficial” tally, according to state officials, between October 2017 and Jan. 11, 2018. Last year, during the 2016-17 flu season, the state reported only four flu deaths. Yet many experts are saying that it’s still better to get a flu shot than to pass, even in years when it’s less effective (see “Protect Yourself from Flu” sidebar below).



  • Cold symptoms include a sore throat, a runny and/or congested nose, and a nagging cough. A fever is uncommon, but some people might experience a slight one while battling a cold.
  • Flu symptoms are more severe than a cold and often come on fast. They include fever (100°F or higher), headache and/or body aches, chills, fatigue, sore throat, cough, and nausea and vomiting. Flu symptoms require medical attention if you have difficulty breathing, experience pain or pressure in your chest or abdomen, or have bouts of dizziness and confusion.

Why Is the Flu So Widespread?

While the news headlines may have you wondering, “Do flu shots work?” the flu vaccine is usually 50 to 70 percent effective. Unfortunately, last year’s vaccine was in the 32 to 39 percent range, and this year’s vaccine is even lower—possibly as low as 10 percent, according to some estimates.

One factor behind the serious flu outbreak may be the severe weather in the Northeast: extremely cold temperatures make the immune system less effective at combating viruses. Complicating the 2017-18 outbreak is a shortage of the IV bags doctors need to rehydrate and deliver medication to people with severe flu. The bags are produced in Puerto Rican factories, and production has been hard-hit by the 2017 hurricane season. Another problem doctors and flu patients are facing is a shortage of Tamiflu, an antiviral drug that can shorten the duration of flu and ease its ill effects if given early enough after symptoms develop.

Authorities had some advance warning on this year’s outbreak. A recent study focusing on the Australian flu season—which coincides with summertime in the U.S.—estimated that the vaccine was only 10 percent effective.

“It’s important every year that we monitor the Australian flu season because the following flu season in the U.S. and Europe could be similar,” says Slobodan Paessler, MD, a professor in the department of pathology at the University of Texas Medical Branch at Galveston. “When the flu vaccine isn’t terribly effective in Australia, U.S. and European health authorities prepare for a potentially severe flu season.”

do flu shots work

Fever is one of multiple flu symptoms that can make life miserable. Others include headache, chills, muscle aches, fatigue, and sore throat.

Do Flu Shots Work? If So, Why Are They Less Effective This Year?

The flu vaccine protects against three or four flu viruses. Each year, it’s updated due to the fact that flu viruses constantly change. Scientists from the World Health Organization predict which viruses are likely to be most active during the upcoming flu season based on year-round surveillance data from more than 100 countries.

It isn’t always possible, unfortunately, to accurately predict which strains of flu will circulate during flu season. And if a different flu virus takes hold, there isn’t time to produce a new vaccine that can protect against it. It takes about six months to produce large quantities of the flu vaccine, according to the CDC.



  • Children under age 5 are particularly vulnerable to flu because they typically spend a lot of time with other young children who may be carrying the virus. It spreads easily via sneezing or touching toys and other objects with unwashed hands.
  • Older adults are also high risk for flu and its complications because their weakened immune systems make it harder for their bodies to fight flu. They’re also more likely to have age-related conditions—heart disease, lung disease, diabetes, cancer, kidney disease, or liver disease, for example—that worsen the effects of the virus.
  • Others at risk are people whose immune system is weakened by a health condition like leukemia, HIV/AIDS, or viral hepatitis. Those who are taking drugs that suppress the immune system (for example, chemotherapy, or medications used to treat autoimmune conditions like rheumatoid arthritis) are also at greater risk.

The flu vaccine can also be rendered less effective if any of the flu viruses included in the vaccine mutate. This seems to be a factor behind the 2017-18 outbreak, experts believe.

Australian health officials have pointed to the emergence of a vaccine-resistant strain of H3N2 flu; while this strain of flu was included in this year’s vaccine, the mutation means the vaccine is less effective at combating it.

The CDC says that about 80 percent of people who have the flu have this strain of the virus. “H3N2 is a bad virus,” Daniel B. Jernigan, MD, MPH, director of the CDC’s influenza division, told the New York Times. “We hate H3N2.”

The same story, published on Jan. 8, noted, “This winter’s flu season is turning into a ‘moderately severe’ one that might get worse because of an imperfect vaccine and steady cold weather, flu experts and public health officials said this week.”

Treating Flu Symptoms

The flu outbreak has prompted a heavy search for flu treatment advice. Over-the-counter (OTC) painkillers and fever reducers can help you feel more comfortable when you have flu symptoms, but they won’t affect how long it lasts. Typically, a flu will last around three days but in some cases, you may feel ill for two weeks or more. (See our post “How Long Does the Flu Last?“)

Many over-the-counter cold remedies contain acetaminophen (Tylenol), so if you’re taking OTC medications, check labels carefully to ensure you don’t inadvertently overdose on the drug. Also, drink plenty of fluids to avoid dehydration. Chicken soup really can help, since it provides fluids and nutrition.

It’s vital to take precautions to avoid spreading the flu to others:

  • Wash your hands often, and try to avoid touching your fingers to your face, since you could transfer the virus to household objects.
  • Disinfect objects that are shared (such as doorknobs, faucets, telephones, and television remote controls).
  • Cover your mouth with your forearm (not your hand) or turn your head down and into your upper arm when you cough.
  • Family members who don’t have the flu may want to discuss with their doctor whether a preventive course of Tamiflu is advisable.


The answer to the question “Do flu shots work?” is: Yes, they generally do, so you should still consider getting the flu vaccine if you haven’t already. (The flu season in the U.S. lasts from fall through winter, with the peak season typically form November through March, according to the Centers for Disease Control and Prevention.)

While a flu shot can never offer a cast-iron guarantee of protection, it can ease the severity of flu symptoms if you’re unlucky enough to catch the virus. And studies show that the flu vaccine can significantly reduce the risk of dying from flu-related complications such as pneumonia, particularly in the cases of babies and young children. If you’re an older adult, ask your doctor about the high-dose flu vaccine—studies suggest it is highly effective in seniors.

Meanwhile, taking these steps can help you fight off flu symptoms:

  • Increase your resistance to infections by getting adequate rest, exercising every day, and keeping your home and hands as clean as possible to eliminate disease agents.
  • Avoid large crowds, especially if you know that a sick person or people will be there, or if you’re sick.
  • If flu is circulating, be particularly careful about washing your hands after using public restrooms (and open public restroom doors with a paper towel instead of your bare hand). Also be sure to use the disinfectant wipes provided by many stores to wipe the handle of shopping carts. As an added precaution, carry a small bottle of alcohol-based hand sanitizer in your purse or pocket, and use it frequently when you are out.
  • Be alert for flu symptoms (such as diarrhea, nausea, fever, aches and pains, and vomiting) and for signs you may be developing pneumonia (such as chest pain, cough, and fever).
  • If you develop symptoms you think may be impending flu, contact your doctor immediately, since it is possible you may benefit from an anti-viral medication such as Tamiflu. This can prevent the flu virus from spreading in the body, and shorten the duration of symptoms—however, it needs to be taken within 48 hours of the onset of flu symptoms.

As a service to our readers, University Health News offers a vast archive of free digital content. Please note the date published or last update on all articles. No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.

Tags: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , ,

Kate Brophy

Kate Brophy is an experienced health writer and editor with a long career in the UK and United States. Kate has been Executive Editor of the Icahn School of Medicine … Read More

View all posts by Kate Brophy

Enter Your Login Credentials
This setting should only be used on your home or work computer.