As a result of variations with influenza each year, the vaccine is often adapted each year to tackle the most prominent and prolific strains.
But cases of the flu dropped so significantly last year meaning scientists have not has as much information upon which to base their design for this year’s flu vaccine.
Professor Michaelis told Express.co.uk: “The efficacy of the flu vaccines depends on how well the virus strains, which are used for the vaccines, match the influenza viruses that will actually be circulating…After a year largely without flu cases, such predictions are more difficult than normal.”
The molecular medicine expert added: “Low flu levels in the human population mean that it is more likely that new strains, against which we have little pre-existing immunity, replace the old ones, against which we have already developed some level of immunity in the past.
“At the same time, unexpected changes can also affect the efficacy of the vaccines, because they may not match well. Indeed, early data seem to suggest that some influenza virus strains, which used to be among the most dominant ones in humans, may have largely or completely disappeared.
“If other unexpected influenza viruses can fill this gap, this may result in a particularly bad flu season.”
He added vaccination for both Covid and the flu this year is crucial.
Professor Michaelis said: “Hopefully, high vaccination rates and increased caution turn the dire projections into self-defeating prophecies.”