All members of the Cheonghae naval unit who contracted COVID-19 are presumed to have the highly transmissible delta variant.

Senior health official Park Young-joon said Wednesday that the 301-member unit had 272 cases total. 

Analysis on 64 cases came up with 64 having the delta variant. The official said, considering epidemiological traits and the sailors' exposure to the virus, all others are highly likely to also be infected with the same strain.

He added that none of the service members became critically ill.  

The Cheonghae Unit was flown home last month, cutting short their mission in Africa, following the mass outbreak. A majority have now fully recovered and been released from quarantine while four remain in isolation.