FRIDAY, Jan. 8, 2016 (HealthDay News) -- Flu activity remains low in the United States, possibly due to the mild temperatures that have blanketed much of the nation, federal health officials said Friday.
But officials expect flu activity to pick up in the next few weeks, so anyone who hasn't gotten a flu shot should get one now.
"Flu is relatively low, but it's starting to increase and there is still time to get vaccinated," said Lynnette Brammer, an epidemiologist in the influenza division at the U.S. Centers for Disease Control and Prevention.
This year's slow start to the flu season isn't out of the ordinary -- other flu seasons have had the same pattern, Brammer said.
"The last three years' flu season was earlier than normal, so this one feels late," she said. "But this is really not unusual for flu season."
Brammer expects flu activity to pick up in the next few weeks. In past similar flu seasons, the peak didn't come until February, and in one case the flu peaked in March, she said.
Milder weather may be one factor delaying this year's flu, Brammer said. But it's only one factor of many that affect how flu spreads. Other factors include how many people are immune because they've been vaccinated and the low number of people with flu who could infect others.
Right now flu activity is widespread in North Carolina and Maryland, but not in the rest of the country, according to Brammer.
Even when flu is epidemic, it's not too late to get a flu shot, Brammer said. "But you get the most benefit if you get vaccinated before there is a lot of flu activity," she said. "The sooner, the better."
In a typical flu season, flu complications -- including pneumonia -- send more than 200,000 Americans 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.
Virtually everyone older than 6 months of age is advised to get a flu shot. The exceptions are people with life-threatening allergies to the flu vaccine or any ingredient in the vaccine, according to the CDC.
Pregnant women are at high risk and should get vaccinated. Women with newborns also need to 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, the CDC says.
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 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, Brammer said.
That happened because the virus that experts had predicted to be predominant wasn't, and the new H3N2 virus was not included in the vaccine, she 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, Brammer said.
Based on what has happened so far, Brammer thinks this year's vaccine is a good match for the circulating flu viruses and is an improvement over last year's shot. "It's a better match for sure," she said.
Plenty of vaccine is still available, but Brammer said supplies may be dwindling in some regions. In some areas of the country you may need to make a couple of calls to find the vaccine, she added.
"It's not too late to get vaccinated," she said. "We are expecting a lot more flu coming down the road. So this is still a great time to go get vaccinated."
For more on flu, visit the U.S. Centers for Disease Control and Prevention.