https://www.npr.org/2021/05/04/993537622/biden-sets-new-goal-for-at-least-70-of-adults-to-be-vaccinated-by-july-4

These same stats are being used in all media, with “56%” of US adults vaccinated, the President wants the mark to be 70%.

Independence Day = 70
Think of the 56 signers on the Declaration of Independence

Think of the the UK strain, where it was first said to be 70% more infectious, before being downgraded to 56%.

United Kingdom = 70
56 year old Boris Johnson (at the time)