The extended expiry date apply to Moderna batches imported into Vietnam from Wednesday, the Ministry of Health said.
"The update on expiry date does not change the vaccine's quality, safety and effectiveness," the ministry said, adding that the extension is applied globally by Moderna, not just in Vietnam.
The Moderna Covid-19 vaccine was approved for emergency use by the health ministry in June 2021.
A standard course is two 100 mcg doses given 28 days apart and to people aged 12 and above. A booster shot for adults contains 50 mcg of the vaccine.
By Feb. 25, the health ministry had received and distributed over 14 million Moderna vaccine doses.
The health ministry has also extended the expiry date of the Pfizer and Cuban Abdala vaccines from six to nine months.