Hard-hit countries including Spain and Italy now expect to get their first shots in early 2021.
By mid-morning the pan-European Stoxx 600 index was up around 0.7%, marking a third day of gains.
That builds on a 5% rally this week.
Battered sectors including travel stocks are among the gainers.
British Airways-owner IAG rose as much as 6%, while easyJet was up around 4%.
Better than expected earnings numbers have also helped the mood.
According to data from Refinitiv, 68% of European companies reporting third-quarter numbers have beaten estimates.
German energy firm E.ON the latest to join that trend.
Its shares gained around a percent after it said demand was recovering faster than expected.
Dutch bank ABN Amro also beat forecasts on Wednesday.
But its shares tumbled 4% as it said it was still wary about the coming months.
Overall though, the optimism was evident, with traditional safe-haven bets like government bonds and gold all flat or lower.
