Many public health officials and journalists credited masks, lockdowns, and social distancing for the disappearance of the flu. Critics pointed out that the flu also disappeared in places like Sweden, which did not have lockdowns, mask mandates, or social distancing rules. Critics also pointed to long-standing research demonstrating that virus-bearing aerosols are too small to be stopped by masks and that, even in perfectly still air, these aerosols are so small that they hang in the air for many days before settling to the ground, making social distancing a joke. Particularly embarrassing for those cheerleading all these heavy-handed measures is that the flu disappeared several months before the first mask mandate was imposed

On the other side of the debate are some who have suggested that cold and flu infections were simply rebranded as Covid due to flawed PCR testing. However, in many countries flu testing did not stop, yet the number of flu tests coming back positive nonetheless fell off a cliff. Some countries even conducted more flu tests than usual and still found nothing.

Viral interference also partly explains why different respiratory viruses have different seasons, rather than plaguing us all at the same time. For example, colds caused by rhinoviruses are much less frequent during influenza season.

The past two years do not stand out from previous years despite the disappearance of the flu. The two winter Covid peaks are clearly within the same order of magnitude as previous bad flu seasons, very similar to the 2018/2019 or the 2015/2016 winter flu seasons. Covid displaced influenza and is now playing the role of "old man's friend".

Influenza is also back with a vengeance in South Africa, despite the fact that it is not normally influenza season at this time of year. An out-of-season arrival of the flu signals that viral interference from Covid has ended, allowing other viruses to come back even before seasonal environmental conditions are ideal.