Flu season fears have sparked a run on pharmacies in the United States and made it harder to find a vaccine in certain areas.

Christina Tarantola, a pharmacist at Kings Pharmacy in Park Slope, Brooklyn, usually only sees about five people a day looking for flu vaccines.

“We did 60 on Friday, and over the weekend we did about 50. It’s been crazy,” Tarantola said Monday.

The U.S. Centers for Disease Control and Prevention warned the public earlier in January that flu activity has been more severe this season. This year’s flu also seems to consist primarily of a viral subtype called H3N2, which has been associated with more severe seasons in the past.

New York City’s health department said Friday that it does not anticipate shortages of the flu vaccine, but people may have to hunt for a pharmacy that still has the shot in stock. Calls placed to several pharmacies Monday morning showed that a Duane Reade on Wall Street had the vaccine, while a Harlem Walgreens was temporarily out of stock and expected to replenish its supplies later in the day.

The CDC “still [understands] there are spot shortages out there and individuals may have to check around several places to find vaccine,” spokesperson Tom Skinner said in an email. “People should call their provider ahead of time.”

Flu vaccine makers project that they will make about 135 million doses of flu vaccine for this season, and about 128 million doses have already been distributed, according to the CDC.

Drug maker Novartis has shipped more than 36 million doses of its vaccine Fluvirin in the U.S. this year -- a 25 percent increase over the previous year, the company said in an emailed statement Monday.

“All of the doses have been distributed to our customers, and the supply meets the demand we received for this influenza season,” the company says. “We are working with public sector stakeholders and our distributors to help ensure that the vaccines are broadly available. Additionally, we are evaluating options to meet increased demand if needed.” 

Flu vaccines can come in various "presentations," like pre-filled syringes or vials of varying sizes, designed for different age groups. Sanofi Pasteur spokesperson Donna Cary says that while certain "presentations" of its flu vaccine have sold out, there's still more than enough of the vaccine around in other forms.

"We have something available for every age group," Cary said.

While Sanofi is still keeping tabs on the current season by collaborating with the CDC and local health officials, the company is also starting up production of next year's flu vaccine.

On Saturday, New York Gov. Andrew Cuomo declared a public health emergency throughout the Empire State. That decision temporarily lifts the rule prohibiting pharmacists from administering vaccines to anyone under 18 years old. Now pharmacists can give the flu shot to patients as young as six months of age.

More than 19,000 influenza cases have been reported throughout the New York, far surpassing the 4,404 confirmed cases in all of the 2011-2012 flu season. As of Jan. 5, there were 2,884 people hospitalized with the flu, according to the state Department of Health. Two children in New York and 18 children nationwide have died from this year’s seasonal flu.

“We are experiencing the worst flu season since at least 2009, and influenza activity in New York state is widespread, with cases reported in all 57 counties and all five boroughs of New York City,” Gov. Cuomo said in a statement Saturday.

Symptoms of influenza are similar to the common cold, but are more severe and develop more swiftly. A runny nose and sore throat are often accompanied by a fever and coughing. It’s not too late to get vaccinated -- the flu season usually lasts through the end of March, but can sometimes stretch out until May.