ACCRA, Dec 1 (Reuters) - Ghana"s health ministry detected the country"s first cases of the Omicron COVID-19 variant on passengers who arrived at Accra international airport following sequencing carried out on Nov. 21, the head of the Ghana Health Service said on Wednesday. Officials have so far declined to specify how many positive cases were detected when the samples were sequenced on Nov. 21. Health Service director general Patrick Kuma-Aboagye said that the case originated from Nigeria and South Africa. "The good thing is that among the community tests we"ve done so far, we haven"t seen any Omicron within the community of Ghana," Kuma-Aboagye said during a vaccination awareness event on Wednesday. "The danger is if someone has Omicron and is incubating, it would not be found at the airport, so we still have to be extremely careful," he added. December is Ghana"s most important tourism month and officials expect an influx of visitors from countries that have already detected the new variant, Kuma-Aboagye said.