San Francisco is preparing to open two safe injection sites this summer in hopes of getting a handle on rampant drug use and cutting down on the spread of disease.

Mayor London Breed touted the effectiveness of safe injection sites in her inaugural address. In addition, people always point to Vancouver as a shining example of how how well the centers can work.

But on Friday, opponents, including a man from Vancouver, held a protest in opposite of the sites and poked holes in that theory.

But there are plenty of critics voicing opposition to a plan that is not protected by California law.

"We are ready to fight San Francisco if they insist to open up illegal drug injection centers," said Frank Lee, who is part of the coalition opposing safe injection sites.

A gloomy projection about a strategy San Francisco is deploying to deal with needles and drug use.

"From being a drug addict, or recovering drug addict myself, we absolutely know that when a drug addict becomes high, they're not looking for recovery, they're looking for their next hit!" said Bishop Ron Allen, International Faith Based Coalition.

State Sen. Scott Wiener has been an early advocate of safe injection sites and insists supplying medical personnel onsite is far better than the alternative.

"When someone is injecting in an alleyway, that's not helping anyone," Wiener said. "There has never been an overdose death at one of these safe injection sites."

Wayne Lo came from Vancouver to participate in Friday's protest in San Francisco. He said more than 400 people overdosed in the Vancouver metro area in 2017. An NBC Bay Area review of the latest date from British Columbia's coroner's service confirms a spike -- Vancouver had 38 overdose deaths in 2018 and 366 in 2017.

But Wiener contends that is a commentary on a drug crisis, not the centers themselves.

"Our injection problem with heroin, with meth, has been going up everywhere,whether or not you have a safe injection site." Wiener said. "We have a problem that is spiraling out of control."

The two safe injection sites San Francisco plans on opening this summer are privately funded because California does not provide legal protection to those who work at or use them. Sen. Wiener is co-author of a bill that could change that in San Francisco if it passes the senate.