Flu Shots To Be Tweaked For Greater Efficiency Next Season: CDC

After failing to predict early on the strain of influenza that would infect humans last season, health authorities are taking extra precautions for next season.

The 2014-15 flu season caught health agencies off-guard as they did not expect the H3N2 strain to predominate. As a result, previous season vaccines were only 18.6 percent effective against the disease causing strain. Last season was described as moderately severe with thousands of elderly adults succumbing to the flu, reports US News & World Report.

To avoid a repeat, the flu vaccine is being tweaked to fight H1N1 which caused the 2009 pandemic, H3N2 that caused illness last year and two influenza B viruses. These strains are known to be causing illness around the world and are also expected to circulate in the US.

However researchers do not offer guarantees.

"Influenza activity is unpredictable in terms of what virus will predominate and the exact timing of the season, and both of these things, along with others, can have a large impact on season severity. Therefore, we can't know at this point what the next flu season will look like," CDC epidemiologist Lynnette Brammer reportedly said.