Egg-based flu vaccines offer lower levels of protection against certain virus subtypes

As the number of states reporting local flu activity has more than doubled since last week, researchers have found that egg-based influenza vaccine production may be yielding less effective vaccines. The seasonal flu vaccine is most commonly given as the standard-dose trivalent flu shot which is made from virus components grown in eggs, but the results of a new study published in the journal PLOS Pathogens has shown that the egg-based vaccine offers a low level of protection against influenza A H3N2 viruses. The study, conducted by researchers at The Scripps Research Institute, has come out following findings that the seasonal influenza vaccine was about 42% effective at preventing illness during the 2016-2017 flu season. The CDC notes that flu vaccine reduces the risk of becoming ill with the virus by 40% to 60%, and tends to be more effective for influenza A H1NA and influenza B viruses. That rate drops to...