Hug the grandparents, celebrate with friends and hit the beach. Whatever your plans once you’ve been vaccinated for COVID-19, there’s a good chance it involves getting on a plane.

More than half of Americans and Europeans may have been vaccinated by mid-2021, according to analysts at Goldman Sachs Group Inc. Some forecasts aren’t as rosy. But if the rollout goes smoothly, and there’s a way for passengers to prove they’ve been inoculated, air travel could start to recover.

Speed is of the essence, and not just to protect lives: Summer is when European airlines make most of their revenue.