Japan's health ministry has decided that people who received their second coronavirus vaccine dose six months earlier will be eligible for a booster shot.
The plan was approved at a ministry advisory panel meeting held on Monday.
Pfizer-BioNTech vaccine is the only one now approved in Japan for booster shots.
While acknowledging that a booster shot should basically be given to people who have been fully vaccinated for more than eight months, officials said exceptions could be made to those who were vaccinated six months earlier.
They said it will be up to municipalities to decide whether such exceptions could be made, depending on factors that include how infections are spreading in the areas.
The ministry initially planned to provide boosters at an interval of eight months, taking into account the examples set by some countries in Europe and the US.
But officials decided that more flexibility can be granted since some overseas data suggests the efficacy of vaccines is halved in less than six months.
Participants also agreed on the ministry plan to encourage booster shots for the elderly and those with underlying diseases who are more prone to developing serious conditions.
They agreed that employees at nursing care facilities as well as medical workers should also be provided booster shots.
Approval also was given to using a Pfizer-BioNTech booster for people who initially received two Moderna or AstraZeneca vaccine shots.