How Effective Will the Flu Vaccine Be?

Learn what ‘efficacy’ means to understand these researchers’ predictions.

Illustration of a syringe

A study by Rice bioengineers and physicists predicts that this fall’s flu vaccine — a new H3N2 formulation for the first time since 2015 — will be about as effective as the disappointing vaccines of the past two years. Flu vaccines are prepared months in advance based on predictions about the flu strain that’s expected to dominate the coming year. Vaccine efficacy is measured by how well it prevents the flu from spreading. This year’s 22 percent efficacy means that in the vaccinated population, 22 percent fewer people will get the flu compared to the unvaccinated population.

“The vaccine was changed for 2018–2019, but unfortunately it still is a mismatch for many of the circulating strains of the virus,” said Michael Deem, Rice’s John W. Cox Professor of Biochemical and Genetic Engineering and professor of physics and astronomy. A newly updated analysis for 2018–2019 suggests that a new cluster of virus strains is emerging. The Rice method predicts that the current vaccine will not protect against these newly emerging strains.

Predicting flu vaccine efficacy has historically been time-consuming and expensive, but over the past 12 years Deem has developed a rapid computational test known as pEpitope (pronounced PEE-epih-tope) that can predict vaccine efficacy within hours using readily available genetic sequence data. The method accurately predicted the efficacy of 2016 and 2017 vaccines.

— Jade Boyd