DAR ES SALAAM, June 1 (Xinhua) -- Tanzania's health authorities on Wednesday described the polio vaccination campaign for children aged below five years as very successful.

       Ummy Mwalimu, the Minister for Health, said 12.1 million children aged below five years were vaccinated against the disease between May 18 and May 21 in mainland Tanzania and Zanzibar against its initial target of vaccinating 10,313,887.

       "This is an impressive achievement," Mwalimu told a news conference in the capital Dodoma.

       She said another polio vaccination for children aged below five will be conducted in July and August on dates to be announced later and urged people to vaccinate their children en masse.

       The first round of the vaccination campaign was conducted from March 24 to March 27 and reached more than 1 million children in four regions of Mbeya, Njombe, Ruvuma and Songwe bordering Malawi after the country reported an outbreak of the virus.

       Malawi declared an outbreak of wild poliovirus on Feb. 17 after a case was detected in a young child, said the statement.

       Tanzania was certified as polio-free in 2015, after years without a new polio case, despite a sensitive polio surveillance system, said the statement, adding that due to its sustained high coverage of oral polio vaccines, Tanzania has not detected a polio case since 1996.