Found this in the album posted by Chris Chau on Flickr.
Children queuing at a vehicle whith the inscription "Luthe(ran)". Lutheran Mission cared for refugees, so this could be something like oral vaccination against polio or vitamin treatment. No information about date and place is given.
After discussion the place was identified as the blocks built for squatters after the fires in around 1956. It's likely the distribution of milk to children.