Online fraudsters are jacking up the price of false COVID vaccine cards in the wake of a new federal mandate, the latest in a series of scams that seeks to exploit widespread concern and misinformation about the deadly pandemic.

The average cost of a fake «registered» US Centers for Disease Control and Prevention vaccine card doubled to $200 in the days following President Joe Biden’s Thursday announcement that federal employees and others would be required to get a COVID shot, according to new research from Israeli cybersecurity firm Check Point Software Technologies.

Oded Vanunu, Check Point’s head of products vulnerabilities research, says that when the company started monitoring the issue in January, COVID-related black market activity was mainly found on darknet websites geared toward dealers. Those dealers would buy the fake documentation in bulk and resell it.

Since then, the activity has shifted to groups on Telegram, an encrypted messaging app. The groups offer anonymity, as well as bigger reach and scale. Over the past month, the number of sellers on Telegram has jumped tenfold to about 10,000.

The number of people subscribed to those groups has jumped, too. Before Biden’s announcement, some bigger groups had as many as 30,000 subscribers and followers. After the news, those numbers surged, with some groups peaking at roughly 300,000 members, a number the researchers hadn’t seen before.

Representatives of Telegram didn’t immediately respond to a message seeking comment.

«Our expectation is that the black market for fake coronavirus vaccination cards will continue to thrive as more policy requiring vaccination proof gets rolled out,» Vanunu said in a statement released with the report.

The spread of fake vaccine documentation online is part of a broader problem authorities have tried to combat. Facebook, Twitter and other social media sites have batted false information about the disease since the early days of the pandemic. The FBI has warned about vaccine scams and has disrupted online frauds that used the pandemic to raise false donations.

And the Federal Trade Commission has cautioned consumers to be on the lookout for scammers pretending to be government authorities in an effort to get into victims’ bank accounts.

The Biden administration’s plan is designed to address both the surging delta variant and the slowing pace of vaccinations in the US. It mandates vaccines for all federal employees and contractors who do business with the federal government, as well as health care workers at Medicare and Medicaid facilities.

Businesses with more than 100 employees must also require their workers to be vaccinated or to get tested weekly for infection. In total, the plan could reach up to 100 million people, roughly two-thirds of the US workforce.

The plan also encourages entertainment venues such as sports arenas and concert halls to require proof of vaccination or a negative COVID-19 test for patrons to gain entry.

The market for fake documents is expanding globally. Check Point researchers found documents for sale in nine new countries that it didn’t spot a month ago, bringing the total number of countries spotted to 28.

In addition to the fake CDC vaccination cards, the researchers also saw counterfeit versions of UK National Health Service cards, vaccine certificates for numerous other countries, European Union digital certificates and COVID PCR test results.