"If you're talking about a small party like I might have at my house for six or eight people who are all fully vaccinated, I do not believe, at this point, we need to put masks on to be next to each other," he said on CNN. "But if there were 100 people, and, of course, how are you really going to be sure about people's vaccination status?'"
Martha's Vineyard is close to Provincetown, Massachusetts, where a spread among vaccinated people over the July 4 Independence Day holiday prompted new mask guidelines from the Centers for Disease Control and Prevention (CDC).
As a result of the outbreak, scientists discovered that vaccinated people who got breakthrough Covid cases had the same viral load as those who did not get the vaccine, leading the CDC once again recommended even those who are vaccinated continue wearing their masks indoors in areas with "high" or "substantial" spread.
The spread of the highly contagious coronavirus delta variant has fueled a new surge in infections, with the CDC reporting rising numbers of cases in nearly 90 per cent of US jurisdictions.
President Joe Biden, who served as Vice President under Obama, will not be in attendance.
"While President Biden is unable to attend this weekend, he looks forward to catching up with former President Obama soon and properly welcoming him into the over-60 club," a spokesperson for The White House told Axios website.
Obama's spokeswoman did not respond to requests for comment.