He said it was like "the worst flu you can imagine".
Read more: Brian May says anti-vaxxers are 'fruitcakes'
The star has been updating fans on Instagram about his progress, and was still testing positive several days after getting ill.
However, he has now said that he and EastEnders legend Dobson, 72, have tested negative.
“Dr and Mrs May got negative results in our COVID lateral flow tests today,” he said.
“We will check one more time tomorrow - and then consider ourselves safe to rejoin humanity - but still very carefully - on what is for us Day 12 since infection.”
“It’s very possible to get this thing more than once,” he added.
Earlier this week, the 74-year-old chart star urged his fans to get vaccinated.
May, who is triple jabbed, wrote: "I can't emphasise to you enough - this is not the response that my body would have made on its own. It's making this response because I've had three Pfizer jabs."
"I beg you, and implore you, to go and get jabbed if you're not already," he told his fans.
"Because you need the help."
Watch: Brian May begs fans to get vaccinated, following COVID battle