As fresh global concerns over the spread of the COVID-19 Delta variant mount, former US president Barack Obama will reportedly host about 700 guests for his 60th birthday party this weekend at Martha's Vineyard, where he has a home.<p>Holding large gatherings even while in the grip of the pandemic seems to be embedded in the DNA of Americans. On July 4, US President Joe Biden welcomed around 1,000 people to the White House to mark the country's Independence Day and to tout his administration's "achievements" in fighting the pandemic.