Trivalent and quadrivalent vaccines offer similar protection against flu B illness
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Trivalent and quadrivalent inactivated influenza vaccines offered similar protection against influenza B illness during four recent influenza seasons, study findings showed.
“We wanted to study whether adding another B lineage virus in the inactivated influenza vaccine to make it a quadrivalent formulation from a trivalent one improved vaccine effectiveness against outpatient medical visits for any influenza B illnesses,” Manjusha Gaglani, MBBS, director and founder of the Center for Research in Vaccines and Infections at the Baylor Scott & White Medical Center, Texas A&M College of Medicine, told Healio.
Gaglani and colleagues used the U.S. Influenza Vaccine Effectiveness Network to analyze data on 25,019 outpatients aged 6 months or older, enrolled within 7 days of illness onset during six influenza seasons starting with 2011-2012. According to the study, upper respiratory specimens were tested for influenza virus type and B lineage. Then, using logistic regression, the researchers estimated the effectiveness of the trivalent and quadrivalent vaccines by comparing the odds of influenza B infection overall and by B lineage among vaccinated vs. unvaccinated participants.
Overall, they found that even though the quadrivalent vaccine provided better protection against the B lineage during four influenza seasons from 2013-2014 to 2016-2017, it did not protect better than the trivalent vaccine against outpatient medical visits for any influenza B illness. According to the study, during those four influenza seasons when both vaccines were widely used, overall effectiveness against any influenza B was 53% (95% CI, 45-59) for the quadrivalent vaccine vs. 45% (95% CI, 34-54) for the trivalent vaccine.
“Despite providing better protection against the influenza B lineage not included in trivalent vaccine, quadrivalent inactivated influenza vaccine may not afford better protection against any influenza B illness in the outpatient setting,” Gaglani said. “There is some cross-protection afforded with trivalent vaccine containing either of the two influenza B lineage viruses, B/Yamagata and B/Victoria. The potential for cross-protection against the B lineage not included in trivalent vaccine is important to consider during vaccine strain selection of the B lineage virus to be included in the trivalent vaccine.” – by Caitlyn Stulpin
Disclosures: Gaglani reports receiving grants from the CDC. Please see the study for all other authors’ relevant financial disclosures.
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