Nigeria will continue to keep vigil over polio to make sure that the virus does not re-emerge in the West African country, a presidency statement said Sunday.

The African nation was declared polio-free on Saturday by the World Health Organization, following the absence of any case of the wild polio virus since July 24, 2014.

In spite of the achievement, surveillance activities and immunization will continue across Nigeria to keep the country polio-free at all times, the presidency statement, signed by presidential spokesman, Femi Adesina, said.

The Nigerian leader has directed all government ministries, departments and agencies involved in the polio eradication effort to remain proactively engaged and on guard against the re-emergence of the polio virus in the African most populous country, the statement added.

Nigeria was among three countries, which included Afghanistan and Pakistan, left to eradicate polio as of 2013. The other two countries have only recorded low cases of polio since that year.