The hard-hit United States has passed a hopeful milestone as half its adults have had at least one Covid vaccine dose and from Monday all its over 18s will be eligible to get their shot, AFP reported. The positive news from the world's hardest-hit country comes amid easing restrictions for several European nations and the launch of a quarantine-free travel bubble between Australia and New Zealand.

Roughly 130 million Americans aged 18 and over have now received a shot, representing 50.4% of the adult population, according to the Centers for Disease Control and Prevention (CDC) on Sunday.

The US is a world leader in vaccinations, but a recent surge in new daily infections prompted top pandemic advisor Anthony Fauci to warn Sunday that the country remains in a "precarious position."

White House efforts to speed up vaccinations hit a snag when health authorities reported six cases of young women developing a clotting disorder after taking the Johnson & Johnson shot. But Fauci predicted the J&J jab would soon return to circulation, albeit possibly with some restrictions or warnings on its use.

Australia and New Zealand got a glimpse of normal life Monday, as a long-awaited quarantine-free travel bubble opened across the Tasman Sea. Family members tearfully reunited at Sydney's airport, while others readied for their first outbound flights in more than a year after New Zealand closed its doors in response to the pandemic.

Portugal lifted its suspension on flights to and from Britain and Brazil for "essential trips," and was set to allow restaurants, shopping centers, high schools and universities to reopen from Monday.

Switzerland was also set to start the week with a step towards normality, with outdoor seating permitted at restaurants and bars and cinemas, sports facilities, and in-person classes at universities re-opening.

Israelis stepped into the streets without masks on Sunday for the first time in a year, as the country vaccinates its way out of a coronavirus nightmare.