The World Health Organisation has listed Nigeria as one of the nine African countries where measles outbreaks have resurfaced.
WHO in a statement signed on Wednesday by Collins Boakye-Agyemang, its Spokesman for Africa, listed other countries to include Chad, Cameroon, DR Congo, Liberia, Guinea, Madagascar, Mali and Uganda.
The world health body said the global measles crisis is an urgent wake-up call to the need for countries to ensure that all children - no matter where they live - receive life-saving vaccines.
It said African countries have experienced a resurgence of measles outbreaks in the last 12 months, adding that Madagascar, in particular, has had a large measles outbreak affecting more than 122,000 cases in the months between October 2018 and April 2019.
Measles is a highly contagious disease that accounts for 13 per cent of all vaccine-preventable deaths in children younger than 5 years in Africa, infecting nine in ten people who are not vaccinated.
According to the WHO/UNICEF coverage estimates as of 2017, only 16 countries in the World Health Organization's African Region had achieved 90 per cent or more immunisation coverage of the first dose of measles vaccine (MCV1).
Across the region, MCV1 coverage has stagnated, at 70-73 per cent since 2009.
At the launch of the ninth African Vaccination Week on Wednesday in São Tomé and Príncipe, immunisation partners stressed the importance of countries remaining vigilant in the fight against vaccine-preventable diseases.
The theme for this year's African Vaccination Week is: 'Protected Together: Vaccines Work!', emphasising the power of vaccines in saving lives and keeping everyone healthy, from infants to elders.
The African Vaccination Week, from 22 to 28 April, also celebrates the vaccination heroes who help expand the coverage of immunization services across the African region - from parents and community leaders to health workers and innovators.
"We need to work together to improve immunization delivery so that all children are protected from preventable diseases. Recent disease outbreaks on the continent remind us of the urgency of this goal," the statement quoted Dr Matshidiso Moeti, WHO Regional Director for Africa, as saying.
"Outbreaks of measles in Madagascar and Ebola in the Democratic Republic of the Congo underscore the need for increased investments in immunization as a fundamental part of strengthening primary health care systems," she said.
WHO said vaccines are one of the most effective and cost-effective public health interventions available. Yet, one in five children in Africa still does not have access to all the necessary and basic vaccines a child should receive.
The body said every year, more than 30 million children younger than 5 years in Africa fall sick due to vaccine-preventable diseases. Of them, more than half a million die - representing 56 per cent of the global deaths related to vaccine-preventable diseases.
It pointed out that, in Africa, vaccine-preventable diseases also impose an economic burden of US$ 13 billion every year - funding that could be used to fuel economies and drive development.
In 2017, African Heads of State endorsed the Addis Declaration on Immunisation at the African Union Summit, committing to reach all children with life-saving vaccines.
While political will for immunisation across the region is high, WHO said African Vaccination Week 2019 is a reminder for countries to renew their commitments and redouble efforts to achieve universal access to vaccines.