Earlier this month the Food and Drug Administration approved a drug called Truvada that is supposed to give otherwise healthy people a certain level of protection when having sex with someone who is HIV positive.

At the local AIDS Task Force, the news was greeted with a certain amount of excitement.

“It started a big buzz about four months ago,” said Chris Wise, director of client services at the task force. “They were showing positive results. Scientifically, it was very exciting. It’s the first thing that showed some effectiveness.”

At the same time, Wise said, there is plenty of cause for caution.

There is a certain amount of confusion and lack of understanding about the drug, Wise said. So before people celebrate what they regard as good news, perhaps they should hear what could be called the bad news first.

“It’s just been approved,” Wise said. “It was OK’d on July 16. But you’ve got to be able to wrap your mind around all of the side effects.”

Truvada, she said, can reduce bone density, which can lead to bone fractures. It can have an effect on the liver, kidneys and heart. It speeds the aging process, Wise said.

The drug costs $45 a day. That’s $1,400 or more per month.

The biggest worry is misunderstanding of the drug, she said, adding, “it’s not a get-out-of-jail free card.”

“We don’t know if it will work in everyone,” Wise said.

The pill has to be taken at exactly the same time every day.

“If you don’t take it at the same time it lowers its effectiveness,” Wise said.

In fact, skipping a day or taking the drug at different times on different days can cause the person taking the drug to develop a resistance. That resistance can in turn be passed on to a spouse or partner, she said. That would be particularly bad if the person who has HIV is already being treated with Truvada.

That is what worries Wise. Her clients are by and large careful and responsible, but if you don’t have a high degree of medical literacy, Wise said, the drug can be misused. A person might develop a false sense of security, thinking they are somehow protected.

“You can’t just go blindly into this thinking you are completely safe because of this pill,” Wise said. “When you get it wrong, it can change your life forever.

“You don’t want to get a prescription and go to a club and hand a pill to a friend and say they’ll be OK tonight,” Wise said.

That’s unlikely at $45 a pill, but if someone fails to understand the drug and engages in reckless behavior, “you can put me at risk and someone else and it just snowballs,” Wise said.

The numbers point out that a lot of people are being less than careful.

“We aren’t decreasing the number of new cases,” Wise said, noting that the infection rate in some American cities is as high as in sub-Saharan Africa, she said.

The AIDS Task Force is seeing its client load increase by about 2 percent a year, even as some clients die or move away, which shows there are plenty of new cases of HIV in this area. Many of the new cases are youths, and many are young women.

An HIV or AIDS diagnosis isn’t the death sentence it was 20 years ago thanks to new methods of treatment, but the increasing numbers of cases show HIV and AIDS aren’t going away.

There is no magic bullet.