Borders will remain closed to individuals. Operators who are authorized to continue to operate in transportation of goods can cross borders at the international checkpoints, but they must strictly follow the measures required at the checkpoints. Source
Foreign trucks can cross border to the nearest transit center. Driver needs to fill in health form. For transit cargo to the third country, foreign trucks are allowed to transit center in Lao PDR and transit to Lao's trucks. If it is necessary for foreign trucks to carry cargo to the third country, the vehicle are subject to sterilization and must change to Lao driver.
Sources: https://covid19.gov.la/order_29032020_e.html; https://www.thaitruckcenter.com/tdsc/NewsDetail?Isveiw=1&id=142&