Travel curbs expand as more cases reported

Hong Kong expanded a ban on entry for non-residents from several countries as global health authorities raced to curb a potential outbreak of the Omicron virus, while Australia's cabinet will review containment steps on Tuesday after five tested positive.
Omicron - first reported in southern Africa and which the World Health Organization (WHO) said carries a "very high" risk of infection surges - has triggered global alarm, with border closures casting a shadow over a nascent economic recovery from a two-year pandemic. In Australia, the five travellers with Omicron are all vaccinated and in quarantine, health officials said, adding they are asymptomatic or display very mild symptoms.
BioNTech, Moderna and Johnson & Johnson are working on vaccines that specifically target Omicron in case their existing shots are not effective against the new coronavirus variant, the companies said on Monday.
A top South African infectious disease expert said Omicron appears to be more transmissible than previous variants, including to people with immunity from vaccination or prior infection.
China will deliver another 1 billion doses of Covid-19 vaccines to Africa and encourage Chinese companies to invest no less than $10 billion in the continent over the next three years, President Xi Jinping said on Monday.
China's imports from Africa, one of its key sources of crude oil and minerals, will reach $300 billion in the next three years, Xi said, adding that the two sides would cooperate in areas such as health, digital innovation, trade promotion and green development.
Reinfections with the virus that causes Covid-19 are rarely severe, new findings suggest. Researchers in Qatar compared 1,304 individuals with a second SARS-CoV-2 infection against 6,520 people infected with the virus for the first time. Reinfected patients were 90% less likely to be hospitalised compared to patients infected for the first time, and no one in the study with a second infection required intensive care or died from Covid-19, said Dr. Laith Jamal Abu-Raddad of Weill Cornell Medicine-Qatar in Doha.
"Nearly all reinfections were mild, perhaps because of immune memory that prevented deterioration of the infection to more severe outcomes," he said. It is not clear how long immune protection against severe reinfection would last, the researchers noted. If it does last for a long time, they speculate, it might mean that as the coronavirus becomes endemic, infections could become "more benign."
Smartwatch alerting systems for early detection of Covid-19 infection are coming closer to reality, researchers reported on Monday in Nature Medicine. They tested their new system, developed with open-source software, in 2,155 wearers of Fitbit, Apple Watch, Garmin watches or other devices. Ultimately, 84 of the volunteers were diagnosed with coronavirus infections - including 14 of 18 people without symptoms.
Overall, the researchers' algorithms generated alerts in 67 (80%) of the infected individuals, on average three days before symptoms began. "This is the first time, to our knowledge, that asymptomatic detection has been shown for Covid-19," they said. Presently, the system mainly depends on measurements of wearers' resting heart rate, said study leader Michael Snyder of Stanford University School of Medicine in California. When watches can report other health data such as heart rate variability, respiration rate, skin temperature, and oxygen levels, it will become easier to distinguish the Covid-19 cases from other non-Covid-19 events, researchers said.