Chief pharmacist Ali A. Yasin, left, gives flu information to Juan Castro, right, after injecting him with influenza vaccine on Jan. 15, 2013, in New York City. Treatment within the first 48 hours is most effective and can reduce severe illness, hospitalization and death. (Mario Tama/GETTY IMAGES)

This flu season is worse than average and hitting the elderly particularly hard, with sharp increases in hospitalizations in recent weeks, federal officials said Friday.

Many parts of the country are still experiencing high, and in some places increasing, levels of flu, according to data for the week ended Jan. 12, the latest available. But overall flu activity is easing slightly, said Thomas Frieden, director of the Centers for Disease Control and Prevention.

“We’re in the middle of our season,” Frieden said in a telephone briefing with reporters. “It’s worse than average. . . . And it’s a particularly severe season for the elderly.”

It’s not too late to get a flu shot, and officials urged people to do so despite spot shortages that may mean consumers have to look harder. Officials also urged those with flu symptoms, especially the elderly, young children and other high-risk groups, to start antiviral treatment early. The two FDA-approved influenza antiviral treatments are Tamiflu (oseltamivir phosphate) and Relenza (zanamivir).

As many as a third to one-half of those hospitalized for flu are not getting antiviral treatment this season, he said. Treatment within the first 48 hours is most effective and can reduce severe illness, hospitalization and death.

“We’re not doing as well as we should be doing,” Frieden said.

The numbers and rates of hospitalizations and deaths are expected to rise further in the next week or so as the season continues, he said. Twenty-nine children or teens have died this season, compared with 34 pediatric deaths reported during all of the last flu season. Maryland reported on Friday its first flu-related pediatric death since the 2009-2010 season, when there were two such deaths. No details were given.

Those at high risk include people with asthma, diabetes, heart disease, pregnant women and children with neurological disorders. If they have flu symptoms, they should get treated early, even if a rapid flu test comes back negative, he said.

In the Washington area, hospitals and physicians said the crush in the emergency rooms and their offices had eased somewhat, but overall visits remain much higher than last year, which was an unusually mild and short flu season.

“I would hope that we’ve seen the peak and may have now plateaued,” said William Frohna, chief of the emergency department at MedStar Washington Hospital Center. “Last week we were a notch busier than we are this week.”

Influenza season typically progresses in phases. After cases begin to increase, complications develop and are reflected later in reports of hospitalizations and deaths.

This year’s flu season arrived about a month before authorities normally see it, and the earliest since the 2003-04 flu season. CDC officials had warned that the early arrival and the predominant strain circulating this year could make for a bad flu season.

The primary strain is the H3N2, an influenza A virus that has been associated in the past with more severe flu seasons.

Even though this season’s vaccine is well-matched to the primary strain, bad flu seasons take the greatest toll on the elderly, who account for about 90 percent of all flu-related deaths. Each year, thousands of people die from the flu. “In a bad flu year, tens of thousands die,” Frieden said.

In the 2003-2004 flu season, the CDC has estimated there were more than 48,000 influenza-associated respiratory and circulatory deaths.

For the two weeks ended Jan. 12, lab-confirmed influenza hospitalizations for those 65 and older climbed sharply. The hospitalization rate for that age group is 82 per 100,000 people, compared with 18 per 100,000 people for all age groups this season. The high rate for the elderly is comparable to that of 2003-04, another bad season when H3N2 was the predominant strain.

But officials pointed out that this season is not over.

Thirty states — including Maryland and Virginia — are experiencing high levels of influenza-like illness, up from 24 states the previous week. But the proportion of outpatient visits for flulike illness, while still high, fell slightly for the week ended Jan. 12.

To address spot shortages of some versions of Tamiflu for children, the Food and Drug Administration has given the maker of Tamiflu approval to release about 2 million doses of a reserve stock of capsules. FDA Commissioner Margaret Hamburg said the medicine is the same as Tamiflu in circulation, but package inserts lack some information pharmacists need for mixing a pediatric version. The agency has alerted pharmacists and other providers to provide them with current information before dispensing.

Officials on Friday also raised their estimates on how much flu vaccine is available this season. Based on updated estimates from manufacturers, 145 million doses are available and about 129 million have already been shipped. The vaccine is about 62 percent effective, in line with past years.

A new flu vaccine approved Wednesday by the FDA may also help bridge any gaps. It’s the first influenza vaccine made using a technology that does not require the virus to be grown in chicken eggs, a long and complicated process that is how most flu vaccine is made. The timing of the approval was not related to the current flu season, an FDA spokeswoman said.

In a clinical trial, the vaccine was about 44.6 percent effective against all influenza strains, not just the three contained in this year’s vaccine, the FDA said.

Manon Cox, chief executive of Protein Sciences, said her company has already made 150,000 doses of the new vaccine, called Flublok. She is hoping to make them available during this flu season if the partner drug company can finish bottling it in time. The company still needs to label and box the vials and ship them back to Protein Sciences, headquartered in Meriden, Conn., before the vaccine can be shipped out to meet orders.

She is hoping to receive the vials by the end of January and mid-February at the latest. It typically takes 14 days for people to develop antibodies after receiving flu vaccine.

The MedStar Washington Hospital Center was running low on rapid flu test kits, and until more were delivered Thursday, doctors were using them on only the sickest patients, he said.

At the Inova health-care system, which has more than 1,700 beds in Northern Virginia, measures aimed at protecting patients, staff and visitors from flu exposure are still in effect. These include banning visitors younger than 18, as well as visitors who have any flu-like symptoms. But the number of confirmed flu cases for the week of Jan. 6 has dropped slightly from the previous week, a spokesman said.