What you need to know about the coronavirus right now

Olympics organisers to unveil "playbook"
Olympics organisers prepared on Tuesday to unveil their latest "playbook" of rules to control Covid-19 infections as Japan's government pondered whether to extend a state of emergency.

Organisers' rules already mandate the wearing of masks by athletes and others in most situations and frequent testing for Covid-19. Athletes and members of the media, whose movements will be restricted, will be subject to GPS monitoring for the first 14 days of their stay in Japan.

Australia reports two new Covid-19 cases in Melbourne
Australia's Victoria state on Tuesday reported two new locally acquired cases of Covid-19 in the state capital Melbourne, both linked to an existing cluster that prompted renewed social distancing measures in the city.

Victoria state Health Minister Martin Foley said the cases were both traced to infections reported from a residential townhouse complex in Melbourne, raising the cluster to six. Hundreds of residents were urged to undergo testing and to self-isolate.

Novavax vaccine more than 90% effective in U.S. trial
Novavax Inc on Monday said its Covid-19 vaccine was more than 90% effective, including against a variety of concerning variants of the coronavirus in a large, late-stage U.S.-based clinical trial. The study of nearly 30,000 volunteers puts Novavax on track to file for emergency authorization in the United States and elsewhere in the third quarter of 2021, the company said.

Novavax said the vaccine was generally well tolerated and side effects were generally mild. Novavax remains on track to produce 100 million doses per month by the end of the third quarter of 2021 and 150 million doses per month in the fourth quarter of 2021, the company said.

U.S. exceeds 600,000 Covid-19 fatalities
The United States on Monday crossed the grim milestone of 600,000 Covid-19 deaths, according to a Reuters tally. At the same time, slowing vaccination rates threaten the Biden administration target of having 70% of U.S. adults receive at least one shot and 160 million fully inoculated by July 4.

The early success of the U.S. vaccine rollout has had a huge impact on the pace of Covid-19 fatalities in the country. The U.S. seven-day Covid-19 death average has fallen by almost 90% from its peak in January. The country reported 18,587 coronavirus-related deaths in May - about 81% less than in January, Reuters data showed.

Delta variant doubles risk of Covid hospitalisation
The Delta coronavirus variant doubles the risk of hospitalisation compared with the previously dominant variant in Britain, but two doses of vaccine provide strong protection, a Scottish study found on Monday.

The researchers said two doses of vaccine provide much better protection than one dose against the Delta variant, and the delay in easing England's lockdown would help more people get second doses and build up their immune responses.