Vietnam and Korea started a Patent Prosecution Highway (PPH) pilot program on 1 June 2019. Its not a full but trial system, aimed to last for 2 years and limited to only 100 PPH requests per annum. The request is free and filed with on or prior to requesting substantive examination. The time period for examination will then be shortened. The benefit is for Korean applicants who can now easily conform their Vietnam patent with the KIPO grant. The applicant can make amendments to conform during examination phase to achieve this. Given that Koreans file many patents in Vietnam, demand will outstrip the 100 available requests.
More details can be found here.