Next year’s flu vaccine will be no more effective than last year’s flu vaccine. How effective is that? When put up against H3N2, the type of influenza A that infected most people in the US in each of the past two years, it’s about 19 percent effective. That’s the estimation of researchers at Rice University, who used a method of prediction known as pEpitope for gauging the effectiveness of proposed flu vaccine formulations. A Rice University news release reports that the latest pEpitope study became available online this week in Clinical Infectious Diseases. The researchers point out that a 20 percent efficacy means that in a population, 20 percent fewer vaccinated people will get the flu compared to the unvaccinated people. The reason for the low efficacy, researchers say, is that, while the vaccine has been changed for 2018-19, it still contains two critical mutations that arise from the egg-based vaccine production process. Those mutations are believed to have halved the efficacy of flu vaccines in the past two seasons. They believe that egg adaptations like those that reduced the efficacy of vaccines in 2016 and 2017 are unavoidable as long as flu vaccines are produced in eggs, as they are for next year’s model. When the researchers compared the efficacy of the egg-based vaccine with an experimental vaccine produced from insect cells via reverse genetic, they found that the cell-based vaccine, which did not have the egg-passage mutations, had a predicted efficacy of 47 percent, the average value of a perfectly matched H3N2 vaccine.