Despite the higher effectiveness of the quadrivalent inactivated influenza vaccine against the added B virus lineage, trivalent inactivated influenza vaccine provided comparable protection against influenza B and each B lineage, according to study results published in Clinical Infectious Diseases.
Type B influenza viruses contribute significantly to the annual global disease burden of influenza, including hospitalization and mortality in children and adults. There are 2 distinct influenza B lineages (Victoria and Yamagata) that can be identified on the basis of antigenic relatedness to reference hemagglutinin proteins of strains B/Victoria/02/87 and B/Yamagata/16/88, respectively. During the last 30 years, both B virus lineages have co-circulated globally. The trivalent vaccine for B-lineage influenza viruses selects strains twice annually for each of the northern and southern hemisphere vaccine formulations; the quadrivalent vaccine contains both B-lineages from inception. Therefore, researchers conducted an investigation of the comparative effectiveness of the 2 types of vaccine.
Using data from the US Influenza Vaccine Effectiveness Network, which consisted of 5 study sites across the United States, including in Michigan, Pennsylvania, Texas, Washington, and Wisconsin, researchers enrolled patients seeking ambulatory care for acute respiratory illness over the course of 6 influenza seasons from 2011/2012 to 2016/2017. Combined nasal and oropharyngeal swab specimens (nasal swabs only in children aged <2 years) were tested for influenza type A and B virus infection, and B lineage confirmed using real-time reverse transcriptase polymerase chain reaction.
Of the 2374 cases of reverse-transcriptase polymerase chain reaction-confirmed influenza B infection included in the analysis, 71% (1693) were the result of infection with the B/Yamagata lineage, 27% (n=637) were B/Victoria lineage, and 2% (n=44) were undetermined B lineage. Roughly half of the cases were children aged <18 years.
During the 6 influenza seasons of the study period, influenza B viruses accounted for approximately 25% of all influenza cases. The effectiveness of the trivalent vaccine against any influenza B illness was 58% (95% CI, 52%-63%). During the 4 influenza seasons when both the trivalent and the quadrivalent vaccines were widely used (2013-2014 to 2016-2017), the overall trivalent vaccine effectiveness against B was 45% (95% CI, 34%-54%) compared with 53% (95% CI, 45%-59%) for the quadrivalent vaccine.
During the 2013/2014 to 2016/2017 influenza seasons, the odds of any influenza B infection were similar among recipients of the trivalent and those of the quadrivalent vaccine, including odds of infection with B/Yamagata (relative odds ratio [rOR], 1.11; 95% CI, 0.79-1.56) or B/Victoria viruses (rOR, 1.88; 95% CI, 0.91-3.87). Relative odds of infection with the B lineage after receipt of the trivalent vaccine during the 4 seasons indicated no difference between the trivalent and quadrivalent vaccines (rOR, 0.87; 95% CI, 0.56-1.34). However, individuals who received the trivalent vaccine had significantly higher odds of infection with mismatched B-lineage viruses compared with patients who received the quadrivalent vaccine (rOR 1.78; 95% CI, 1.13-2.79).
“Enhanced influenza surveillance to understand epidemiology of B lineage circulation including the burden of illness with each B lineage, along with cost-effectiveness estimates for trivalent versus quadrivalent vaccine distribution in different age groups should help national health authorities to make informed decisions regarding recommendation of trivalent vs quadrivalent influenza vaccines,” concluded the researchers.
Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.
Gaglani M, Vasudevan A, Raiyani C, et al. Effectiveness of trivalent and quadrivalent inactivated vaccines against influenza B in the United States, 2011-2012 to 2016-2017 [published online February 1, 2020]. Clin Infect Dis. doi:10.1093/cid/ciaa102