I don't know about a fake version in the US, but there was a fake vaccine scam in India:

https://edition.cnn.com/2021/07/05/india/india-fake-covid-vaccine-scam-intl-hnk/index.html

New Delhi (CNN)Thousands of people have fallen prey to an elaborate wide-ranging scam selling fake coronavirus vaccines in India, with doctors and medical workers among those arrested for their involvement, authorities say.

At least 12 fake vaccination drives were held in or near the financial hub Mumbai, in the country's western Maharashtra state, said Vishal Thakur, a senior official of the Mumbai police department. "They were using saline water and injecting it," Thakur said. "Every fake vaccination camp that they held, they were doing this."

An estimated 2,500 people were given fake shots, he said. The organizers charged their victims fees for the shots, earning up to $28,000 in total.