Maria Sharapova shocked the tennis world after announcing that she tested positive for the banned substance meldonium at the Australian Open, but Sharapova was not the only athlete to get caught using the drug. The World Anti-Doping Agency announced Friday that nearly 100 athletes have tested positive since Jan. 1, which was when the drug ban was put into effect.

Sharapova went public with the news about her positive test earlier this week, saying that she was taking the drug for medical issues. WADA spokesman Ben Nichols told the Associated Press that there have been "99 adverse analytical findings" for the drug so far this year. Sharapova is the most high-profile athlete to test positive, but many of the names of the other athletes are not yet public.

The AP reports that seven of 16 confirmed cases are from Russian athletes. Sharapova spoke about her use of the drug, saying that she has been using it for over a decade for health-related issues. The tennis star said that she did not know the drug had been banned. Meldonium was added to the banned list starting in 2016.

Meldonium is a "blood-flow boosting" drug that is manufactured in Latvia. Sharapova has not yet been hit with a ban for her positive test, but the AP notes that athletes can face a ban of "up to four years" for the first positive test. The WADA first announced that meldonium would be placed on the banned list in September 2015 after finding that some athletes started using it for performance-enhancing.

"We are not really at any stage surprised when a substance is put on the list and all of the sudden there are positive cases," David Howman, WADA's director general, said Thursday.

Sharapova has been provisionally suspended by the International Tennis Federation while her case moves through the investigation process. She has lost some sponsorships since the news was announced, including with Nike, Tag Heuer and Porsche. Sharapova said that she had been taking the drug mildronate, which is also known as meldonium, to help with low magnesium levels and heart-related issues.

"I know with this that I face consequences," Sharapova said. "I don't want to end my career this way, and I really hope I'm given another chance to play this game."

The news about Sharapova has reverberated around the tennis world, with players like Serena Williams, Rafael Nadal, Andy Murray and Caroline Wozniacki all reacting to the development. Williams spoke about the situation while preparing to play at Indian Wells, revealing that she does not take any supplements.

"I don't. I'm terrified, to be honest. It would just be a really bad situation if that was me," Williams said. "Just even from a health perspective, I've never been a big fan of taking anything."