Specific directions showing how to forge Covid-19 vaccination cards have proliferated on conspiracy, pro-Trump and anti-vaccination forums throughout the internet in recent weeks, as users have exploited a largely makeshift verification system.

The cards, distributed by the Centers for Disease Control and Prevention, have been handed out to the more than 140 million Americans who have already received at least one dose of a Covid-19 vaccination. The Biden administration has declared it wouldn't create a federal vaccination database, citing privacy concerns, paving the way for the cards to become the country’s default national way to verify if someone has been vaccinated.

And while one state — New York — has embraced a vaccination verification app, there is scant evidence that others are close behind.

While much of the country is in the early stages of deciding how to ask employees, students and travelers to prove they've been vaccinated, most of those entities that have already established a plan rely on those cards. The Silicon Valley company Salesforce announced earlier this month that employees returning to work in person will need to show their cards, and United Airlines said it will require the same of its employees.