How Effective Is the 2018 Flu Shot? Here ’s What You Should Know

Vaccination has been recommended for decades as the best way to protect yourself against flu, but it’s no silver bullet. The shot’s effectiveness varies from year to year, depending on the closeness of the match between that season’s viruses and the vaccine, which is usually reformulated each year. This winter in North America, its performance has been especially poor, leaving people more vulnerable to a virus that’s caused a spike in hospitalizations and deaths. In Hong Kong, schools are starting their Chinese New Year holiday earlier amid a flu epidemic that has claimed more than 100 lives in the city. 1. How effective is the 2018 flu shot? Early findings from Canada indicate a 17 percent effectiveness against the viral strain, known as H3N2, that’s been the main culprit of flu in the U.S. this winter. 2. Why are vaccines less protective against some strains of the flu? One reason has to do with the most-common way flu shots are made. They typically contain killed (or “inactivated”) flu viruses that are grown in chicken eggs. Flu viruses that spread easily among humans tend not to grow as well in chicken eggs as bird flu strains do. This is especially the case for H3N2 viruses, which have been circulating continuously in humans since 1968 and are, therefore, very well adapted to humans as a host. When replicating inside eggs, H3N2 viruses are prone to undergoing adaptive changes that make them better-suited to the egg environment, ...
Source: TIME: Science - Category: Science Authors: Tags: Uncategorized Bloomberg health onetime Source Type: news