Michael D. Reis M.D.

Gaglani, M., A. Vasudevan, C. Raiyani, K. Murthy, W. Chen, M. Reis, E. A. Belongia, H. Q. McLean, M. L. Jackson, L. A. Jackson, R. K. Zimmerman, M. P. Nowalk, A. S. Monto, E. T. Martin, J. R. Chung, S. Spencer, A. M. Fry and B. Flannery (2020). “Effectiveness of Trivalent and Quadrivalent Inactivated Vaccines against Influenza B in the United States, 2011-2012 to 2016-2017.” Clin Infect Dis Feb 1. [Epub ahead of print].

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BACKGROUND: Since 2013, quadrivalent influenza vaccines containing two B viruses gradually replaced trivalent vaccines in the United States. We compared vaccine effectiveness of quadrivalent to trivalent inactivated vaccines (IIV4 to IIV3) against illness due to influenza B during the transition when IIV4 use increased rapidly. METHODS: The US Influenza Vaccine Effectiveness (Flu VE) Network analyzed 25,019 of 42,600 outpatients aged >/=6 months enrolled within 7 days of illness-onset during six seasons from 2011-2012. Upper respiratory specimens were tested for influenza virus type and B-lineage. Using logistic regression, we estimated IIV4 or IIV3 effectiveness by comparing the odds of influenza B infection overall, and by B lineage among vaccinated versus unvaccinated participants. Over four seasons from 2013-2014, we compared relative odds of influenza B infection among IIV4 versus IIV3 recipients. RESULTS: Trivalent vaccines included the predominantly circulating B lineage in four of six seasons. During four influenza seasons when both IIV4 and IIV3 were widely used, overall effectiveness against any influenza B was 53% (95% confidence interval [CI], 45 to 59) for IIV4 versus 45% (95% CI, 34 to 54) for IIV3. IIV4 was more effective than IIV3 against the B lineage not included in IIV3, but comparative effectiveness against illness related to any influenza B favored neither vaccine valency. CONCLUSIONS: Uptake of quadrivalent inactivated influenza vaccines was not associated with increased protection against any influenza B illness, despite higher effectiveness of quadrivalent vaccines against the added B virus lineage. Public health impact and cost-benefit analyses are needed globally.

Flannery, B., R. J. G. Kondor, J. R. Chung, M. Gaglani, M. Reis, R. K. Zimmerman, M. P. Nowalk, M. L. Jackson, L. A. Jackson, A. S. Monto, E. T. Martin, E. A. Belongia, H. Q. McLean, S. S. Kim, L. Blanton, K. Kniss, A. P. Budd, L. Brammer, T. J. Stark, J. R. Barnes, D. E. Wentworth, A. M. Fry and M. Patel (2020). “Spread of Antigenically Drifted Influenza A(H3N2) Viruses and Vaccine Effectiveness in the United States During the 2018-2019 Season.” J Infect Dis 221(1): 8-15.

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BACKGROUND: Increased illness due to antigenically drifted A(H3N2) clade 3C.3a influenza viruses prompted concerns about vaccine effectiveness (VE) and vaccine strain selection. We used US virologic surveillance and US Influenza Vaccine Effectiveness (Flu VE) Network data to evaluate consequences of this clade. METHODS: Distribution of influenza viruses was described using virologic surveillance data. The Flu VE Network enrolled ambulatory care patients aged >/=6 months with acute respiratory illness at 5 sites. Respiratory specimens were tested for influenza by means of reverse-transcriptase polymerase chain reaction and were sequenced. Using a test-negative design, we estimated VE, comparing the odds of influenza among vaccinated versus unvaccinated participants. RESULTS: During the 2018-2019 influenza season, A(H3N2) clade 3C.3a viruses caused an increasing proportion of influenza cases. Among 2763 Flu VE Network case patients, 1325 (48%) were infected with A(H1N1)pdm09 and 1350 (49%) with A(H3N2); clade 3C.3a accounted for 977 (93%) of 1054 sequenced A(H3N2) viruses. VE was 44% (95% confidence interval, 37%-51%) against A(H1N1)pdm09 and 9% (-4% to 20%) against A(H3N2); VE was 5% (-10% to 19%) against A(H3N2) clade 3C.3a viruses. CONCLUSIONS: The predominance of A(H3N2) clade 3C.3a viruses during the latter part of the 2018-2019 season was associated with decreased VE, supporting the A(H3N2) vaccine component update for 2019-2020 northern hemisphere influenza vaccines.

Flannery, B., R. J. G. Kondor, J. R. Chung, M. Gaglani, M. Reis, R. K. Zimmerman, M. P. Nowalk, M. L. Jackson, L. A. Jackson, A. S. Monto, E. T. Martin, E. A. Belongia, H. Q. McLean, S. S. Kim, L. Blanton, K. Kniss, A. P. Budd, L. Brammer, T. J. Stark, J. R. Barnes, D. E. Wentworth, A. M. Fry and M. Patel (2019). “Spread of antigenically drifted influenza A(H3N2) viruses and vaccine effectiveness in the United States during the 2018-2019 season.” J Infect Dis Oct 30. [Epub ahead of print].

Full text of this article.

BACKGROUND: Increased illness due to antigenically drifted A(H3N2) clade 3C.3a influenza viruses prompted concerns about vaccine effectiveness and vaccine strain selection. We used U.S. virologic surveillance and Influenza Vaccine Effectiveness (VE) Network data to evaluate consequences of this clade. METHODS: Distribution of influenza viruses was described using virologic surveillance data. The VE Network enrolled ambulatory patients aged >/=6 months with acute respiratory illness at five sites. Respiratory specimens were tested by RT-PCR for influenza and sequenced. Using a test-negative design, we estimated VE comparing odds of influenza among vaccinated versus unvaccinated participants. RESULTS: During the 2018-2019 influenza season, A(H3N2) clade 3C.3a viruses caused an increasing proportion of influenza cases. Among 2,763 VE Network case patients, 1,325 (48%) were infected with A(H1N1)pdm09 and 1,350 (49%) with A(H3N2); clade 3C.3a accounted for 977 (93%) of 1,054 sequenced A(H3N2) viruses. VE was 44% (95% confidence interval [CI], 37 to 51%) against A(H1N1)pdm09 and 9% (95% CI, -4 to 20%) against A(H3N2); effectiveness was 5% (95% CI, -10 to 19%) against A(H3N2) clade 3C.3a viruses. CONCLUSIONS: Predominance of A(H3N2) clade 3C.3a viruses during the latter part of the 2018-2019 season was associated with decreased vaccine effectiveness, supporting the A(H3N2) vaccine component update for 2019-2020 northern hemisphere influenza vaccines.