Covid could increase blood glucose levels for a while, just as any illness can. Your HbA1c is a measure of approximately what has been going on over last 3 months, approximately. So you could find that HbA1c isn’t too badly impacted . In your situation, I would just wait until the covid infection clears, and then if HbA1c is due , go ahead and have the test. To wait longer than necessary would only have me wondering, perhaps even worrying, too much about the unknown.
Hope you are not too badly hit with the covid symptoms. Get well soon
@gowest12