The flu is here.
One doctor's office in Arlington, for example, treated five cases on Wednesday.
"I hadn't seen anything until today," Dr. Shelle Barber of Family Healthcare Associates said. "I had five cases of flu."
Two had recently been vaccinated; one just last week. It typically takes about two weeks for your body to develop full immunity, Barber said.
The other patient had received a trivalent vaccine, which provides protection against two A strains and one B strain of the flu, but contracted a different strain.
While five cases are not a lot, doctors say it's an indicator that people should start thinking about getting vaccinated.
The Texas Department of State Health Services is encouraging everyone six months and older to get vaccinated for the flu. The supply is plentiful, the department said.
The flu is caused by various influenza viruses. The vaccine is formulated each year to match the strains of flu researchers expect to be circulating.
The new quadravalent vaccines that available this year will protect against four strains of the virus. It is available as a shot for everyone and as a nasal spray for those ages 2 to 49 who are healthy and not pregnant. The quadravalent vaccines, however, are in short supply.
Texas health officials say this year's trivalent vaccine protects against the strains A/California/7/2009 (H1N1), A/Victoria/361/2011 (H3N2) and B/Massachusetts/2/2012.
The four-strain vaccine will also protect against B/Brisbane/60/2008.
Kenna Starnes, a pharmacist at Perrone Pharmacy in Fort Worth, said a steady stream of people have come in to receive flu shots for more than a month.
"The flu can be quite serious," she said. "At the very least, it can put you out of commission for a couple of weeks, and then the fatigue and lingering effects can last another two weeks."
Flu symptoms come on quickly and can be severe. They include fever, coughing, sore throat, aches, chills and fatigue. Most healthy people recover without problems after a week or more, but people 65 and older, pregnant women, young children and people with chronic health conditions are at higher risk for serious complications and even death.
It is especially important for people in those high-risk groups to be vaccinated.
The Centers for Disease Control and Prevention recommends that children younger than 9 who are getting the flu vaccine for the first time should get two doses at least four weeks apart.
People can help stop the spread of the flu and other illnesses by covering all coughs and sneezes, frequently washing their hands and staying home when sick.
People can contact their health care provider, local health department or dial 211 to find out where to get a flu shot. Flu information and tips for protecting against the flu are at TexasFlu.org.