Some areas of the West Coast, which had seen less flu activity than the rest of the nation earlier, have finally been hit by the flu season.
As of Jan. 12, the region of the country that includes California, Arizona and Nevada reported elevated flu activity, up from normal flu activity the week before, according to new numbers from the Centers for Disease Control and Prevention (CDC).
The rest of the country is also experiencing higher than normal flu activity. Forty-eight states reported widespread flu activity, up from 47 states the week before. Widespread flu activity means that more than 50 percent of areas in those states are experiencing flu. [See Flu Activity Still High: How Long Will it Last?]
Thirty states are now reporting high levels of flu activity — up from 29 states the previous week. Ten states are reporting moderate levels, which is down from 16 states the week before. California now reports moderate activity, up from minimal activity the previous week.
We're about halfway through flu season, Dr. Tom Frieden, director of the CDC, said in a press conference today. (Typically, flu activity remains high for 12 weeks before peaking. So far this season, flu activity has remained elevated for five consecutive weeks.)
Health officials expect hospitalizations and deaths to increase in the coming weeks, following the increase in cases. Earlier this month, deaths from flu reached epidemic levels. About 90 percent of deaths are in those 65 and older, Frieden said.
Nine children died a result of the flu during the week of Jan. 6 to Jan 12, bringing the total number of child deaths from flu this season to 29.
Nationally, the percentage of people visiting the doctor for flulike illness was 4.6 percent, down from 4.8 percent the week ending Jan. 5.
The best way to protect yourself from the flu is to get vaccinated, Frieden said. This year's vaccine is 62 percent effective against the disease.
Manufacturers have produced about 145 million doses of flu vaccine, and 129 million have been distributed. There have been reports of vaccine shortages in some areas. People can visit the CDC flu site to find where the vaccine is offered near them, though they might want to call the location first to check if the vaccine is available, Frieden said.
Antivirals can be taken to treat the flu, though treatment must be started early, within 48 hours of onset of symptoms.
Pass it on: The entire United States is experiencing higher than normal flu activity.
Editor's note: This article was updated on Jan. 18 at 12:30 to include infomration from a CDC press conference.
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Rachael is a Live Science contributor, and was a former channel editor and senior writer for Live Science between 2010 and 2022. She has a master's degree in journalism from New York University's Science, Health and Environmental Reporting Program. She also holds a B.S. in molecular biology and an M.S. in biology from the University of California, San Diego. Her work has appeared in Scienceline, The Washington Post and Scientific American.