However, provincial governor Krit Kongmuang dismissed the rumour, saying only the assistant village headman who had been driving people to the vaccination site, his wife and son had tested positive for Covid-19.
Another 20 people who had been in contact with the driver have also been told to isolate themselves and will undergo Covid-19 tests within seven days.
The assistant village headman and his wife had both received Sinovac as their first shot and AstraZeneca as their second.
Meanwhile, a Phetchabun doctor attacked the media for reporting that having thousands of people queue up for their Covid-19 vaccine would spark a new cluster of infections. Her Facebook post attracted many comments both agreeing and disagreeing with her.