CHATTANOOGA, TN. (WRCB)  --  The year is far from over but the Chattanooga-Hamilton County Health Department has already confirmed 21 cases of whooping cough or pertussis this year. There were only 20 confirmed cases in the last five years combined.

"Having four small children at home, that's definitely a concern," says mother Sarah Roberts.  

Sixteen of the 21 cases in Hamilton County were found in children under 6-years-old. Roberts' youngest is 2-years-old and so far healthy. "I wouldn't know how to deal with that if it happened," she says.

"Pertussis is spread by respiratory droplets, coughing, sneezing and then the infant inhales those respiratory droplets. It's a bacterial infection," says Pharmacist Phil Smith.

Whooping cough is typically most severe in infants and can lead to secondary bacterial infections like pneumonia. A series of vaccines for infants called DTaP can begin as early as early as 2-months-old.

Smith says the recent spike in cases is a concern but numbers tend to rise every couple of years. "The number of people that aren't vaccinated outweigh the number of people that are and then you start bringing it back into the environment," he says.

One of the largest groups at risk for spreading the disease are those older than 65 who haven't had the vaccine since childhood. "As you get older you lose that immunity to pertussis and the more people that are vaccinated the better chance you have at not causing a spread of the disease," says Smith.

That's why he says the Advisory Committee on Immunization is recommending those over 65 get the vaccine with pertussis in it. It's called TDaP, otherwise adults should get a tetanus booster shot about every ten years.

The pertussis vaccine for adults is fully covered under Medicare part D at most pharmacies. Check your medical records or with your doctor if you're not sure what type of vaccine you had last.