The virus usually makes its way to the northern hemisphere after spreading in the southern hemisphere, which experiences its flu season from June to August. But the 2020 flu season in the south was virtually non-existent.

Public health experts believed that measures in the southern hemisphere to prevent the spread of Covid-19 also worked to stop the spread of the flu. Though the flu is also a respiratory virus, it is not as transmissible as Covid-19, so mask-wearing and social distancing are more effective at disrupting flu spread than the spread of Covid-19. The low number of cases, paired with the decrease in travel between the northern and southern hemisphere, boded well for the flu season in the north.

Still, Americans were urged to get the flu vaccine to decrease the chances of a feared “twindemic” of flu and Covid-19. More than 192m doses of the flu vaccine were distributed throughout the US by the end of December, according to the CDC, the highest number of doses distributed in a single flu season.

It appears the bulk of those doses have been used.