By Steven Reinberg

HealthDay Reporter

FRIDAY, Dec. 4, 2015 (HealthDay News) -- While relatively few cases of flu have surfaced so far in the United States, health officials say the holiday season will likely change that, so everyone should get a flu shot now.

People will be shopping, traveling and going to gatherings -- all excellent ways to be exposed to flu, said Dr. Michael Jhung, a medical officer in the influenza division at the U.S. Centers for Disease Control and Prevention.

"People get flu when they are around people with flu," he said. "If we can get people to get vaccinated in the weeks before they leave for their holiday trips, that would be ideal."

Now is a great time to get vaccinated, before flu is widespread, Jhung said. "It's December and we don't have much flu activity in the U.S., which is not too surprising."

But low to moderate flu activity is starting to appear in Oklahoma and South Carolina, Jhung said. "That's a sign that flu activity is likely to pick up in a week or two," he said.

The best way to protect yourself from the flu is to get a flu shot, even when the flu is epidemic, Jhung said. "It's never too late to get vaccinated."

In a typical flu season, flu complications -- including pneumonia -- send more than 200,000 people to the hospital. Death rates linked to flu vary annually, but have gone as high as 49,000 deaths in a year, the CDC says.

Pregnant women are at increased risk from the flu. And it's vital that women with newborns get their flu shot to help protect their infants, who can't be vaccinated until they are at least 6 months old.

Also at risk are seniors and people with chronic health problems, such as lung and heart disease.

How effective the vaccine is in preventing the flu depends on how good a match it is to the strains of flu virus circulating that year. Most years, the vaccine is between 40 percent and 60 percent effective, according to the CDC.

Last year, the vaccine offered little protection against the most common flu strain that circulated, an H3N2 virus, Jhung said.

That happened because the virus that experts predicted to be the predominant strain wasn't, and the new H3N2 virus was not included in the vaccine, he explained.

This mismatch caused a severe flu season, especially for the very old and very young, and led to a record number of hospitalizations for flu among the elderly, according to the CDC.

This year's vaccine contains the new H3N2 strain, but it's too early to tell which strains will dominate, Jhung said. "If things continue as they are right now, we will see a season where the vaccine is a good match for the circulating flu viruses," he said.

This year's vaccine also includes two other strains that are expected to be around as well, according to CDC officials.

"Tons of vaccine are available," Jhung said. Manufacturers are expected to produce 170 million to 180 million doses.

Dr. Marc Siegel, an associate professor of medicine at NYU Langone Medical Center in New York City, said "everyone needs to get a flu shot, because it creates a ring of immunity inside your household and protects your pregnant wife or your young child or your elderly parent."

The more people who are vaccinated, there is less circulating virus and fewer people are at risk, he said.

In a year like this, when the vaccine appears to be a good match, one can expect close to a 70 percent decrease in urgent care visits from flu if one has been vaccinated, Siegel noted.

"This means fewer secondary infections like pneumonia, bronchitis, ear infections, fewer heart attacks brought on by flu, fewer hospitalizations and fewer deaths in those who have received the flu vaccine," he said.

More information

For more on the flu, visit the U.S. Centers for Disease Control and Prevention.