What you need to know about the coronavirus right now

Sydney readies for more military support
More defence personnel could begin patrolling Sydney from next week to help enforce lockdown rules as officials on Friday warned of a Covid-19 surge in Australia's largest city after it reported its biggest daily rise in infections yet.

New South Wales state premier Gladys Berejiklian implored Sydney's five million residents to strictly follow existing curbs. "I am a bit tired of hearing people say they don't know what they are supposed to do," Berejiklian said.

U.S. FDA authorizes vaccine boosters for the immunocompromised
The U.S. Food and Drug Administration on Thursday authorized a booster dose of Covid-19 vaccines from Pfizer and Moderna for people with compromised immune systems.

A few other countries, such as Israel and Germany, plan to or have already administered the third shot to avoid another crisis due to the contagious Delta variant of the coronavirus.

South Koreans told to cut holiday travel, work remotely
Prime Minister Kim Boo-kyum urged South Koreans on Friday to minimise holiday travel and asked companies to show flexibility in letting people work from home amid a worsening fourth wave of Covid-19 infections and a shortage of vaccines in the country.

Kim urged those returning from holiday destinations to get tested for Covid-19 especially before clocking in for work.

Peru study finds Sinopharm vaccine 50.4% effective
A two-dose vaccine from China's Sinopharm was 50.4% effective in preventing infections in health workers in Peru when it was seeing a surge in cases fuelled by virus variants, and booster shots can be considered, a study found.
The vaccine, however, was 94% effective at preventing deaths after two doses, it added. It had shown a 78.1% efficacy rate against symptomatic cases in Phase III clinical trials, WHO data showed.

Biden says mask mandates for children not political
U.S. President Joe Biden said on Thursday that having children wear masks is not about politics but about keeping them safe, as Republican governors in some U.S. states are clashing with local officials who are resisting orders banning school mask mandates.

The U.S. Centers for Disease Control and Prevention's recent recommendation that all students and staff wear masks in school regardless of vaccination status has caused confusion and frustration among parents, educators and officials just weeks before many states start a new school year with in-person learning.