Over 700 babies treated in the past year at a Texas hospital will need to be tested for tuberculosis after it came to light that they may have come in contact with a worker found to have the disease. Tuberculosis is more severe for fragile infants who, unable to yet receive the vaccine, are more susceptible to catching the virus and often develop more serious symptoms.

It’s a parent’s worst nightmare. The very place meant to protect their tiny newborns from disease ended up inadvertently potentially placing them in direct contact with tuberculosis. The hospital worker at Providence Memorial Hospital in El Paso tested positive for the life-threatening illness on Aug. 21, but it’s believed he may have been infected for much longer. "We took the date of first signs and symptoms (of the health care worker) and went back three months to determine who is considered 'exposed,'" Armando Saldivar, spokesman for the El Paso Department of Public Health told The Associated Press.

At the moment, it’s unclear how many of the 700 exposed children have already come in for the suggested testing. The worker tested positive for TB in August, but as a safety precaution all babies who passed through the hospital’s nursery from September 2013 until last month, along with 40 hospital workers are advised to be screened.

Tuberculosis is a potentially serious disease that mainly affects the lungs. It is airborne and TB bacteria can spread to others by inhaling a cough or sneeze from an infected individual. The disease can also infect other areas of the body, including the kidneys, spine, and brain.

In the United States, the tuberculosis vaccine is not generally recommended because of the low risk of infection, the effectiveness of the adult TB vaccine, and the potential for the vaccine to interfere with the accuracy of tuberculin skin test reactivity, according to information provided by the Centers for Disease Control and Prevention. However, even if you do choose to administer your child the TB vaccine, this cannot be administered until they are at least a year of age. This age restriction is based on factors such as the vaccine's interference with other vaccines and on the baby's response to the vaccine, Columbia University explained in its Vaccine Safety pamphlet.

Vaccine schedules are put in place in an effort to “avoid weakening, overwhelming, or altering the immune systems of the young child,” the pamphlet reads. Delaying vaccines could risk the child being exposed to a life-threatening illness, while administering the vaccine too early should interfere with the child’s natural immune system.

Still, despite the children’s young age, the chances are that they would have never been administered the TB vaccine in the first place. In the U.S., tuberculosis is quite rare. While many foreign born individuals are administered the vaccine as children, in the U.S. the shot is reserved for “select persons who meet specific criteria and in consultation with a TB expert,” the CDC explained. Even for those in the health field, the TB shot is still not mandatory, although it is strongly recommended.