The Nigerian president's top media aide Garba Shehu said on Saturday that he has tested positive for coronavirus and was in isolation.
Shehu, who is in his late 50s, is in the immediate circle of 79-year-old President Muhammadu Buhari, reports Reuters.
"I can only confirm that (I am) infected by COVID-19 and on treatment in isolation," Shehu said.
Several local newspapers reported that some of Buhari's aides and top officials have contracted the virus, including Information Minister Lai Mohammed.
Mohammed did not respond to calls for comment while a presidency spokesman declined to comment on whether any other official or minister was infected and whether Buhari, who received a booster dose on Tuesday, has been tested.
Buhari and some ministers recently attended summits in Dubai and Turkey after hosting South African President Cyril Ramaphosa last month just as the Omicron COVID-19 variant was detected in Southern Africa and Hong Kong.
Nigeria, which has so far recorded 234,709 confirmed cases with 2,993 deaths, started to offer booster shots this month after confirming its first cases of the Omicron variant among travellers who arrived from South Africa.