The Centers for Disease Control and Prevention (CDC) is warning that the U.S. will experience a flu season this year.

Most states are reporting low or minimal flu activity and not very many cases have been reported to date. 

During the 2020-21 season, there were very few infections reported in the country due to strict lockdowns, widespread mask-wearing, school and business closures and social distancing measures in place.

But with fewer children vaccinated against influenza compared to last year and outbreaks already seen on college campuses, federal officials told CNN that there will be a flu season, even if not as bad as past seasons.

'Overall flu activity is still really low. It's starting to creep up just a little bit,' Lynnette Brammer, lead of the CDC's Domestic Influenza Surveillance team, told CNN.

'That gives us the idea that flu season may be starting.'

According to the CDC, flu activity was 'unusually low' during the 2020-21 season. 

Between late September and late May, just 0.2 percent - 1,675 - of more than 818,000 specimens came back positive.

When the typical flu season can infect as many 56,000,000 - this means that the number of infections was up to 33,000 times fewer than normal.

Local health departments and hospitals across the country reported similar instances. 

At Wayne State University in Detroit, Michigan, researchers looked at data from Detroit Medical Center for the 2019-20 and the 2020-21 flu seasons.

They found that very single one of the 6,830 tests administered for adults, and the 1,441 for children came back negative for Influenza A and Influenza B during the 2020-21 flu season compared to as high as 20 percent during the 2019-20 season.

And, at Akron Children's Hospital, in Ohio, researchers examined data from children treated during the 2018-19, 2019-20 and the 2020-21 flu seasons.