Digital display boards show cancelled flights to London – Heathrow at O.R. Tambo International Airport in Johannesburg, South Africa, November 26, 2021. REUTERS/ Sumaya Hisham/File Photo Australia and several other countries joined nations imposing restrictions on travel from southern Africa on Saturday after the discovery of the new Omicron coronavirus variant sparked global concern and triggered a sell-off on financial markets. But indicating that such curbs may not stem the spread of the variant, Britain said on Saturday it had detected two cases and authorities in Germany and the Czech Republic also said they had suspected cases. Omicron, dubbed a...