The Samoa Observer reported that Samoa's Ministry of Health CEO, Dr Take Naseri, described the seminars as a "public health threat".
"One serious virulent virus can wipe out this population in less than two weeks," Dr Naseri said.
Winterstein took to Instagram to tell her followers why she had cancelled the controversial seminars. In the post she blamed "organised groups ... working hard to sabotage" her.
"This is no joke. The hostile vaccine climate we are all living in today is no joke," she wrote.
In the past the-mother-of-two has claimed parents were "bullied" and "pressured" by doctors to immunise their children.
Winterstein says she is a qualified Integrative Nutrition Health Coach, but is a "huge self-education advocate and big believer that you do not need a qualification to know how to critically think for yourself". An online invitation to one of her workshops reads: "The benefits of vaccines are constantly over-exaggerated and the risk of an adverse reaction severely downplayed by politicians, journalists and GPs."
The World Health Organisation commented on the growing anti-vaccination movement, saying advocates are "quite concerning".
"Their rhetoric is not supported by science," WHO technical officer Lisa Menning told Nine's A Current Affair.
Director of the New Zealand Immunisation Advisory Centre, Nikki Turner, told the Herald in March said she was in favour of allowing people like Winterstein to come to New Zealand to have their opinions heard but warned it was a "historical issue that's been well and truly put to bed".
"They are making a living and a business out of recycling these issues."
Winterstein has previously claimed that extensive testing of vaccinations in Australia had not been carried out, and said many other wives and girlfriends of NRL players had similar views to her.
"The amount of NRL players and their partners who consciously choose not to vaccinate would seriously surprise you," she posted to Instagram in March.
"I know for a fact there are many high-profile, 'influencers' on social media among the sport and wellness industry, who do not vaccinate their children but won't publicly share their beliefs."
Winterstein was the Australian face for the second Australian tour of the conspiracy movie Vaxxed in 2017.
