What would be the goal? If the bog effect exists , the possible extremes are "being locked inside makes infections more common" which should not impact the result (adding people to both pools), or "being locked inside prevents all infections" which would make the deficit larger than reported. (but as noted, it's a call for further study rather than a precise result)

Given that most people were locked inside for a year, and those who didn't get COVID are even more likely to have followed lockdown rules, any control group measured right now would be reflecting the "locked inside" condition.