A New Jersey family is questioning the efficacy of the Johnson & Johnson COVID-19 vaccine after three family members tested positive for the virus after taking the shot in March.

The father, Francisco Cosme, remains critically ill at JFK University Medical Center in Edison. He received the vaccine on March 6 and started feeling sick March 30. Doctors aren't sure why.

"They said we just have to wait every day to see how he responds,” says wife Laura Eugene. “It’s up to him how his body responds. They really don't understand why he's in this condition after being vaccinated so long."

The Johnson & Johnson vaccine efficacy was reported at 72% in clinical trials, but it was better at keeping people who do get sick from being hospitalized.

"A breakthrough infection or a vaccine failure is when a person contracts an infection despite being vaccinated against it,” says Dr. Anthony Fauci. “We see this with all vaccines in clinical trials in the real world, no vaccine is 100% efficacious or effective, which means that you will always see breakthrough infections regardless of the efficacy of your vaccine."

Health experts say this is why we are reminded to continue wearing masks and practice good hygiene even after vaccination.