Winners will be announced in the coming hours and days after 48 million people were able to vote.
Public health experts want the version B.1.617.2 to be made a "variant of concern", the BBC has been told.
Ballots will be counted over two days with the final result for 129 seats at Holyrood expected on Saturday.
Voting has closed for the Welsh Parliamentary elections after queues outside polling stations.
The gap between poor pupils and their classmates is unlikely to narrow without intervention, researchers say.