Flu cases were at an all-time low during the 2020-2021 season. What experts say to expect in next season's vaccine. - USA TODAY

A drop in flu cases is unarguably a good thing, but it raises questions about the upcoming flu season and what the vaccine will look like in the fall.

Though low flu incidence is unarguably a good thing, it raises questions about the upcoming flu season and what the vaccine will look like in the fall.

Together, they predict the four most common strains in the upcoming flu season and recommend what manufacturers should include in the next vaccine.

Based on the available data, the WHO recommended a flu vaccine similar to last season’s, he said, “which makes sense because a very small percentage (of people) on this planet developed immunity to last year’s strains.” .

In a quadrivalent vaccine – which contains four flu strains – the WHO recommended vaccine manufacturers keep two B strains and change out two A strains, said Dr.

Gregg Sylvester, chief medical officer at Seqirus, a cell-based influenza vaccine manufacturer based in North Carolina.

As manufacturers ramp up production of flu vaccine, many Americans wonder what the upcoming season will bring.

The lack of flu cases last season shouldn’t affect the upcoming flu season, Swartzberg said

The fact that many people didn’t get sick during an unusual flu season doesn’t mean their immune systems have weakened and are unprepared for a normal season

It's unknown whether states reopening will trigger a bad flu season, Sylvester said, “but we ought to be prepared for it.”