People who are afraid of needles may be out luck this flu season.

The Advisory Committee on Immunization Practices (ACIP) has recommended against using the nasal spray flu vaccine for the 2016-2017 flu season.

The Centers for Disease Control and Prevention (CDC) will review the advisory panel’s decision before it’s made part of official CDC policy. The final recommendation will be published in the CDC’s Morbidity and Mortality Weekly Report by the start of the fall. 

There are two main types of flu vaccines.

One is the live attenuated or “active” vaccine (the nasal spray). The other is the inactivated vaccine (the shot).

All forms of the vaccine work by triggering the body to create antibodies that protect against the flu virus.

The active version of the vaccine does this with living, but weakened versions, of the flu virus. The inactive version contains dead virus strains.

Because there are many different flu strains, each vaccine protects against at least three different virus strains. The flu virus is constantly evolving, so the CDC recommends people get a flu shot every year.

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Forecasting the flu season

The ACIP made its recommendation last week based on the data collected by groups that monitor the effectiveness of the flu vaccines every year.

Emily Martin, Ph.D., a professor of epidemiology at the University of Michigan School of Public Health, is part of one of these groups.

People are admitted to the study when they seek medical attention for flu-like symptoms. Once it’s confirmed that they have the flu virus, the person is asked if they were vaccinated.

Martin told Healthline that when the field groups encounter a person who had been vaccinated with the nasal spray version of the vaccine, “their rates of flu were not significantly different than the people who did not receive the live vaccine, and higher than the people who received the inactive vaccine.”

Researchers are given the difficult task of predicting which virus strains will be circulating each year. Months of research go into creating the flu vaccines for each season.

The Southern Hemisphere has a flu season that is opposite of the Northern Hemisphere. Researchers in the Northern Hemisphere can use the data collected from the Southern Hemisphere’s flu season to prepare.

“It’s really a feat of science that the flu season ends in April, and by June we know if there are any changes that need to be made to the vaccine.” Martin said.

But even with all of the data that is collected, it's tough to predict the upcoming flu season. The severity of the flu season depends on how good a match the vaccine is, and how severe the viruses circulating are.

“We had a relatively mild season this past season than we did the season before, and some seasons are like that,” Lisa Grohskopf, a CDC medical officer, told Healthline. “We never really know how severe it’s going to be until the season is under way.”

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No spray, no way?

Experts can’t say for sure how recommending against the nasal spray will affect vaccination rates, but they can make predictions based on past data.

“I know parents like the spray over the shot, “ Martin said, but overall, “we didn’t have much use of the spray.”

Martin stresses that the ACIP didn’t vote against recommending the nasal spray because of safety concerns.

“The recommendation … was changed because it doesn’t look like it was working very well, especially compared to what we already have out there,” she said.

Experts are still confident in the effectiveness of the other available flu vaccines.

“The shot is as good as it’s always been.” Martin says.

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When to get the vaccine

Influenza is a potentially deadly virus that usually infects people in the fall and winter. Not everyone who develops the virus will become seriously ill.

However, high-risk groups such as young children and older adults can experience serious complications, even death as a result of the flu virus.

Annual vaccination can prevent infection and complications in these high-risk groups.

The flu season can start as late as January, but according to Grohskopf, flu activity is often reported as early as October.

Everyone should try to get their yearly flu vaccine by October, but Grohskopf says you’re not out of luck if you wait too long.

“As long as the virus is circulating where you live, it’s not too late to get the vaccine,” she said.