SAN JOSE (KPIX) — A spokesperson for online marketplace OfferUp said Thursday the company has removed posts selling fake COVID-19 vaccination cards, disabled those accounts and is working with law enforcement after several attorneys general sent a letter to the company demanding immediate action.

The letter, which was sent on Monday, is signed by nearly all top legal officers in the country, including California attorney general Rob Bonta. The attorneys general demand that OfferUp remove the posts and respond, no later than April 23, with how it intends to comply. The letter includes a picture of a stack of fake vaccination cards found on OfferUp’s website, which includes a logo for the Centers for Disease Control and Prevention.

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The letter comes just weeks after the National Association of Attorneys General wrote another letter to several e-commerce companies about fake vaccination cards that were being sold online at sites that included Shopify and eBay.

COVID-19 vaccination cards have been necessary in some countries for travel and, in some cases, to attend sporting events and large gatherings.

The San Francisco Giants require fans to present a valid original, photo or photocopied vaccination card or proof of a negative COVID result within three days before a game, according to the county’s public health department guidelines.

On Friday, the Golden State Warriors will host their first in-person game at Chase Center since the pandemic began and will also require a vaccination card or a COVID-19 negative result from a test taken 48 hours before tip-off.

“We’re super excited,” said Yoyo Chan, Warriors vice president of government and community relations. “We are accepting the actual physical card that folks receive when they get their vaccinations or a photo of the actual vaccination card.”

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Fans must be at least two weeks out from their last dose to be considered fully vaccinated, she added.

“We trust that our community and our fans can stick to the rules,” said Chan.

The San Jose Sharks, which also hold the same requirements for their fans as the Giants and Warriors, welcome fans into the Shark Tank for the first time on Monday.

But the San Jose Earthquakes, which will host their first in-person match Saturday, will not ask fans for proof of vaccination or a negative COVID test result. Their arena is completely outdoors, said Earthquakes chief operating officer Jared Shawlee.

“All the guidance we get for the COVID safety protocols does come from the state and county officials,” Shawlee said. “I do think that we’re really fortunate, from a venue layout perspective, that we do have so much outdoor space.”

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Chan said the Warriors are ready for Friday’s game. Warriors fans were sent a COVID test they can take at home or they could choose to take a rapid test at the arena.