Leaders of anti-vaccine groups described the coming coronavirus vaccine as a pivotal opportunity to sow distrust in vaccination and laid out planned online campaigns to do so, according to a report from an organization opposing misinformation online.

The report, from the U.K.-based Center for Countering Digital Hate (CCDH), quoted leaked audio from an October conference in which the leaders, many of whom have huge social media followings, discussed strategies to encourage skepticism and fear of vaccines in the months ahead.

The report highlights the ways in which the coronavirus crisis has catalyzed vaccine opponents, as well as the parallels between the tactics used by anti-vaccine groups — such as coordinated messaging — and other purveyors of online misinformation campaigns.

It also illuminates the struggles social media companies face in debunking and policing misinformation about the coronavirus.

Facebook, for example, bans misinformation about the coronavirus and the vaccine, but falsehoods about the virus have slipped through the cracks throughout the pandemic. The company has created a gray area by permitting users to form groups that question and attack vaccines, some of which have hundreds of thousands of members. False claims unrelated to the virus are sent to the platform’s network of third-party fact-checkers, and such stories are left up with a fact-checking label.

Some of the tactics discussed during the online conference from the National Vaccine Information Center include coordinating a message, or “master narrative,” that the virus is not dangerous and that organizations that promote vaccines are not trustworthy, according to the report.

That includes pushing misleading story lines — for example, focusing on instances when people experienced side effects from the vaccine and using those examples to argue dangerous side effects will be widespread. Another strategy is to target online health influencers with large followings and African Americans, playing on their historical skepticism of the medical community due to racist practices.

In recent months Facebook removed two major groups opposing vaccination, including the 100,000-plus-member Stop Mandatory Vaccination, as well as pages belonging to several of the movement’s leading figures. The company did not ban the groups for misinformation, but for spammy and abusive behavior, such as using paid troll farms in North Macedonia and the Philippines to spread messages.

Those bans, the CCDH says, resulted in 3.2 million fewer people who were members or followers of anti-vaccine pages and groups.

But that number is small when compared with the way anti-vaccine groups have grown all year. Anti-vaccine conspiracy-theory accounts grew by nearly 50 percent over the year, starting at 15.5 million followers in 2019 and rising to 23.1 million by December 2020, the report said.

Overall, the 425 anti-vaccine accounts on Facebook, Instagram, YouTube and Twitter have 59.2 million followers, nearly 877,000 more than they had in June.

Barbara Loe Fisher, co-founder and president of the National Vaccine Information Center, said in a statement: “The modern vaccine safety and informed consent movement was launched in the U.S. in 1982 by parents of DPT vaccine injured children and it is stronger and more relevant than ever today, as experimental COVID-19 vaccines fast tracked to market are being distributed under an Emergency Use Authorization. NVIC’s Fifth International Public Conference on Vaccination … was a celebration of freedom of thought, speech and conscience. We stand by the 50 exceptional speakers who presented at our conference and will be making the evidence and informed perspective they provided on medical science, public health policy and law and ethics more widely available in 2021.”

Facebook spokeswoman Andrea Vallone said in a statement: “We are committed to reaching as many people as possible with accurate information about vaccines, and launched partnerships with WHO and Unicef to do just that. We’ve banned ads that discourage people from getting vaccines and reduced the number of people who see vaccine hoaxes verified by the [World Health Organization] and the [Centers for Disease Control and Prevention]. We also label Pages and Groups that repeatedly share vaccine hoaxes, lower their posts in News Feed, and do not recommend them to anyone. We continue to remove accounts and content that violate our policies and are the only company to work with over 80 fact-checking organizations around the world.”