The UK spreads out the time between first and second shot (I think up to 12 weeks), to get more folks the first shot sooner (I don't know about the UAE and Chile). It is a wise policy for the UK, as the first dose does the Lion's share of the job. Their cases dropped 44% over the last week. Israel down over 63% last week.
We are probably approaching the final nosedive of COVID here soon as well.
If J&J had delivered their anticipated 20 million single shot doses last month, and 30 million more in April, then April would have been a much surer bet for collapse of the disease spread. But soon.