(CNN)Two of Africa's Covid experts are clearing out their desks and counting the hours as they prepare to take up new roles offered to them overseas.
Dr. John Nkengasong, head of the Africa Centres for Disease Control and Prevention (Africa CDC), has welcomed his September nomination to lead the US President's Emergency Plan for AIDS Relief (PEPFAR), a position that, if confirmed by the US Senate, he would be the first African to hold.
Earlier the same month, Dr. Chikwe Ihekweazu, who currently heads the Nigeria Centre for Disease Control (NCDC) was appointed to lead the World Health Organization (WHO) Hub for Pandemic and Epidemic Intelligence in the German capital Berlin, WHO said, with the Nigerian physician on course to assume his new position on November 1.
Some experts assert that this coincidental turn of events underscores the health sector brain drain from Africa.
"That's brain drain," said Dr. Uyilawa Okhuaihesuyi, a former president of the Nigerian Association of Resident Doctors.
"They (Nkengasong and Ihekweazu) have seen better offers and they feel it's better to leave for greener pastures to further their careers," Okhuaihesuyi told CNN. "Now is not the best time to leave," he added.
Nkengasong is a decorated Cameroonian-born virologist, who has chaired the Africa CDC since its launch in 2017, and has played a critical role in Africa's coronavirus response, amplifying the need for "rapid access to vaccines."
Nigeria's Ihekweazu, an epidemiologist and public health expert, is famed for strengthening his country's capacity to tackle infectious diseases and has helped it contain the third wave of Covid-19 infections with tracking and testing efforts.
Ihekweazu's strides at the NCDC had been commended by WHO.
Medical brain drain persists
The emigration of African physicians has continued to rise. In 2015, over 13,000 emigrated to the US alone, representing a 27 percent increase over the course of the previous decade, one study found.
Recent data is scarce, but a November 2020 report by the African Union (AU) said that despite the risks of frontline work during the pandemic -- migration to high-income countries remains attractive to health workers from Africa due to "better working conditions, including renumeration and workload."
"If not managed well, increased demand for health workers, especially in specialities like anaesthesiology, will leave considerable gaps in Africa's already weak health systems," the report said.
Many high-income countries were relaxing visa and immigration requirements for health workers in order to meet that demand, the AU said.
"Without the right policies in place, tackling the brain drain from Africa will become an even more challenging endeavour, inevitably leading to an increase in global inequality and neglect of already inadequate health systems."
The medical brain drain already comes at a great cost for Africa, which, according to pre-pandemic WHO figures, only has access to 3 percent of the world's health workers despite suffering "more than 22 percent of the global burden of disease."
"Nothing to worry about"
Africa is fighting off new strains of the coronavirus, and vaccination against the disease has been slow in the continent, where only 60 million of its more than 1 billion people have received a full course of the vaccine.
Nkengasong's imminent exit from the Africa CDC has fueled concerns about the sustainability of the institution's Covid-19 action plan.
Nkengasong, however, told CNN there was nothing to worry about.
"Africa CDC has a