By Justin Udo

PHILADELPHIA (CBS) – This year is the worst year for pertussis, or whooping cough, in over 60 years and researchers say there is a new strain of the bacteria popping up in the United States that may be resistant to the current vaccine that’s been around for almost two decades.

Whooping cough is a highly contagious disease that can strike people of any age, but is most dangerous to children and can be fatal for infants.

Dr. Alan Evangelista is a microbiologist at St. Christopher’s Children Hospital for Children in Philadelphia.

He’s part of the research team that discovered the change in the bacteria.

“This particular [strain] is missing a surface protein. There’s a mutation that stopped making one of the targets. Usually the vaccine has three targets it goes after and this new strain only has two of the targets,” explains Dr. Evangelista.

He says the pharmaceutical industry is looking at ways to fight the bacteria.

“There’s going to be a meeting in March with a lot of the pharmaceutical companies that have the ability to make the vaccine,” says Dr. Evangelista.

Officials say the discovery of this new strain of whooping cough can affect the way vaccines are developed.

Some of the symptoms of pertussis are runny nose, nasal congestion, sneezing, and occasional coughing.