Effects of Influenza Vaccination in the United States During the 2018–2019 Influenza Season

Abstract Background Multivalent influenza vaccine products provide protection against influenza A(H1N1)pdm09, A(H3N2), and B lineage viruses. The 2018–2019 influenza season in the United States included prolonged circulation of A(H1N1)pdm09 viruses well-matched to the vaccine strain and A(H3N2) viruses, the majority of which were mismatched to the vaccine. We estimated the number of vaccine-prevented influenza-associated illnesses, medical visits, hospitalizations, and deaths for the season. Methods We used a mathematical model and Monte Carlo algorithm to estimate numbers and 95% uncertainty intervals (UIs) of influenza-associated outcomes prevented by vaccination in the United States. The model incorporated age-specific estimates of national 2018–2019 influenza vaccine coverage, influenza virus–specific vaccine effectiveness from the US Influenza Vaccine Effectiveness Network, and disease burden estimated from population-based rates of influenza-associated hospitalizations through the Influenza Hospitalization Surveillance Network. Results Influenza vaccination prevented an estimated 4.4 million (95%UI, 3.4 million–7.1 million) illnesses, 2.3 million (95%UI, 1.8 million–3.8 million) medical visits, 58 000 (95%UI, 30 000–156 000) hospitalizations, and 3500 (95%UI, 1000–13 000) deaths due to influenza viruses during the US 2018–2019 influenza season. Vaccination prevented 14% of projected hospitalizations associated with A(H1N1)pdm09 overall and 43% among children aged 6 months–4 years. Conclusions Influenza vaccination averted substantial influenza-associated disease including hospitalizations and deaths in the United States, primarily due to effectiveness against A(H1N1)pdm09. Our findings underscore the value of influenza vaccination, highlighting that vaccines measurably decrease illness and associated healthcare utilization even in a season in which a vaccine component does not match to a circulating virus.

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Influenza vaccine effectiveness against hospitalization in the United States, 2019-2020

The Journal of Infectious Diseases ◽

10.1093/infdis/jiaa800 ◽

2020 ◽

Author(s):

Mark W Tenforde ◽

H Keipp Talbot ◽

Christopher H Trabue ◽

Manjusha Gaglani ◽

Tresa M McNeal ◽

...

Keyword(s):

United States ◽

Influenza Vaccine ◽

Influenza Vaccination ◽

Respiratory Illness ◽

The United States ◽

Vaccine Effectiveness ◽

Influenza Viruses ◽

Current Season ◽

Hospital Resources ◽

Negative Controls

Abstract Background Influenza causes significant morbidity and mortality and stresses hospital resources during periods of increased circulation. We evaluated the effectiveness of the 2019-2020 influenza vaccine against influenza-associated hospitalizations in the United States. Methods We included adults hospitalized with acute respiratory illness at 14 hospitals and tested for influenza viruses by reserve transcription polymerase chain reaction. Vaccine effectiveness (VE) was estimated by comparing the odds of current-season influenza vaccination in test-positive influenza cases versus test-negative controls, adjusting for confounders. VE was stratified by age and major circulating influenza types along with A(H1N1)pdm09 genetic subgroups. Results 3116 participants were included, including 18% (553) influenza-positive cases. Median age was 63 years. Sixty-seven percent (2079) received vaccination. Overall adjusted VE against influenza viruses was 41% (95% confidence interval [CI]: 27-52). VE against A(H1N1)pdm09 viruses was 40% (95% CI: 24-53) and 33% against B viruses (95% CI: 0-56). Of the two major A(H1N1)pdm09 subgroups (representing 90% of sequenced H1N1 viruses), VE against one group (5A+187A,189E) was 59% (95% CI: 34-75) whereas no significant VE was observed against the other group (5A+156K) [-1%, 95% CI: -61-37]. Conclusions In a primarily older population, influenza vaccination was associated with a 41% reduction in risk of hospitalized influenza illness.

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Effects of Influenza Vaccination in the United States During the 2017–2018 Influenza Season

Clinical Infectious Diseases ◽

10.1093/cid/ciz075 ◽

2019 ◽

Vol 69 (11) ◽

pp. 1845-1853 ◽

Cited By ~ 78

Author(s):

Melissa A Rolfes ◽

Brendan Flannery ◽

Jessie R Chung ◽

Alissa O’Halloran ◽

Shikha Garg ◽

...

Keyword(s):

United States ◽

Influenza Vaccine ◽

Influenza Vaccination ◽

Influenza A ◽

Influenza Season ◽

Influenza Virus Infection ◽

The United States ◽

Influenza B ◽

Medical Visits ◽

Influenza A H1n1

Abstract Background The severity of the 2017–2018 influenza season in the United States was high, with influenza A(H3N2) viruses predominating. Here, we report influenza vaccine effectiveness (VE) and estimate the number of vaccine-prevented influenza-associated illnesses, medical visits, hospitalizations, and deaths for the 2017–2018 influenza season. Methods We used national age-specific estimates of 2017–2018 influenza vaccine coverage and disease burden. We estimated VE against medically attended reverse-transcription polymerase chain reaction–confirmed influenza virus infection in the ambulatory setting using a test-negative design. We used a compartmental model to estimate numbers of influenza-associated outcomes prevented by vaccination. Results The VE against outpatient, medically attended, laboratory-confirmed influenza was 38% (95% confidence interval [CI], 31%–43%), including 22% (95% CI, 12%–31%) against influenza A(H3N2), 62% (95% CI, 50%–71%) against influenza A(H1N1)pdm09, and 50% (95% CI, 41%–57%) against influenza B. We estimated that influenza vaccination prevented 7.1 million (95% CrI, 5.4 million–9.3 million) illnesses, 3.7 million (95% CrI, 2.8 million–4.9 million) medical visits, 109 000 (95% CrI, 39 000–231 000) hospitalizations, and 8000 (95% credible interval [CrI], 1100–21 000) deaths. Vaccination prevented 10% of expected hospitalizations overall and 41% among young children (6 months–4 years). Conclusions Despite 38% VE, influenza vaccination reduced a substantial burden of influenza-associated illness, medical visits, hospitalizations, and deaths in the United States during the 2017–2018 season. Our results demonstrate the benefit of current influenza vaccination and the need for improved vaccines.

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Successes and failures of the live-attenuated influenza vaccine, can we do better?

10.1101/424275 ◽

2018 ◽

Author(s):

Laura Matrajt ◽

M. Elizabeth Halloran ◽

Rustom Antia

Keyword(s):

United States ◽

Influenza Vaccine ◽

Mathematical Models ◽

Viral Infections ◽

Influenza Season ◽

The United States ◽

Vaccine Effectiveness ◽

Effective Protection ◽

Live Attenuated Vaccines ◽

Live Attenuated Influenza Vaccine

Live-attenuated vaccines are usually highly effective against many acute viral infections. However, the effective- ness of the live attenuated influenza vaccine (LAIV) can vary widely, ranging from 0% effectiveness in some studies done in the United States to 50% in studies done in Europe. The reasons for these discrepancies remain largely unclear. In this paper we use mathematical models to explore how the efficacy of LAIV is affected by the degree of mismatch with the currently circulating influenza strain and interference with pre-existing immunity. The model incorporates two key antigenic distances - the distance between pre-existing immunity and the currently circulating strain as well as the LAIV strain. Our models show that a LAIV that is matched with the currently circulating strain is likely to have only modest efficacy. Our results suggest that the efficacy of the vaccine would be increased (optimized) if, rather than being matched to the circulating strain, it is antigenically slightly further from pre-existing immunity compared with the circulating strain. The models also suggest two regimes in which LAIV that is matched to circulating strains may provide effective protection. The first is in children before they have built immunity from circulating strains. The second is in response to novel strains (such as antigenic shifts) which are at substantial antigenic distance from previously circulating strains. Our models provide an explanation for the variation in vaccine effectiveness, both between children and adults as well as between studies of vaccine effectiveness observed during the 2014-15 influenza season in different countries.

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Relative Effectiveness of the Cell-Derived Inactivated Quadrivalent Influenza Vaccine Versus Egg-Derived Inactivated Quadrivalent Influenza Vaccines in Preventing Influenza-Related Medical Encounters During the 2018-2019 Influenza Season in the United States

Clinical Infectious Diseases ◽

10.1093/cid/ciaa1944 ◽

2021 ◽

Author(s):

Constantina Boikos ◽

Lauren Fischer ◽

Dan O’Brien ◽

Joe Vasey ◽

Gregg C Sylvester ◽

...

Keyword(s):

Influenza Vaccine ◽

Influenza Season ◽

Relative Effectiveness ◽

The United States ◽

Geographic Region ◽

Vaccine Effectiveness ◽

Influenza Viruses ◽

Study Cohort ◽

Doubly Robust ◽

Quadrivalent Influenza Vaccine

Abstract Background The cell-propagated inactivated quadrivalent influenza vaccine (ccIIV4) may offer improved protection in seasons where egg-derived influenza viruses undergo mutations that affect antigenicity. This study estimated the relative vaccine effectiveness (rVE) of ccIIV4 versus egg-derived inactivated quadrivalent influenza vaccine (eIIV4) in preventing influenza-related medical encounters in the 2018-2019 U.S. season. Methods A dataset linking primary care electronic medical records with medical claims data was used to conduct a retrospective cohort study among individuals ≥4 years vaccinated with ccIIV4 or eIIV4 during the 2018-2019 season. Adjusted odds ratios (ORs) were derived from a doubly robust inverse probability of treatment-weighted approach adjusting for age, sex, race, ethnicity, geographic region, vaccination week, and health status. Relative vaccine effectiveness (rVE) was estimated by (1-OR)*100 and presented with 95% confidence intervals (CI). Results Following the application of inclusion/exclusion criteria, the study cohort included 2,125,430 ccIIV4 and 8,000,903 eIIV4 recipients. Adjusted analyses demonstrated a greater reduction in influenza-related medical encounters with ccIIV4 versus eIIV4, with the following rVE: overall, 7.6% (95% CI 6.5-8.6); age 4-17 years, 3.9% (0.9-7.0); 18-64 years, 6.5% (5.2-7.9); 18-49 years, 7.5% (5.7-9.3); 50-64 years, 5.6% (3.6-7.6); and ≥65 years, -2.2% (-5.4 to 0.9). Conclusions Adjusted analyses demonstrated statistically significantly greater reduction in influenza-related medical encounters in individuals vaccinated with ccIIV4 vs eIIV4 in the 2018-2019 U.S. influenza season. These results support ccIIV4 as a potentially more effective public health measure against influenza than an egg-based equivalent.

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Prediction of influenza vaccine effectiveness for the influenza season 2017/18 in the US

F1000Research ◽

10.12688/f1000research.13198.1 ◽

2017 ◽

Vol 6 ◽

pp. 2067 ◽

Cited By ~ 11

Author(s):

Slobodan Paessler ◽

Veljko Veljkovic

Keyword(s):

Influenza Vaccine ◽

Seasonal Influenza ◽

Influenza Season ◽

Vaccine Effectiveness ◽

Influenza Viruses ◽

Antigenic Drift ◽

Correct Prediction ◽

Seasonal Influenza Vaccine ◽

The Us ◽

Key Factor

Vaccination against seasonal influenza viruses is the most effective way to prevent infection. A key factor in the effectiveness of the seasonal influenza vaccine is its immunological compatibility with the circulating viruses during the season. The high evolutionary rate, antigenic shift and antigenic drift of influenza viruses, represents the main obstacle for correct prediction of the vaccine effectiveness for an upcoming flu season. Conventional structural and phylogenetic approaches for assessment of vaccine effectiveness have had a limited success in prediction of vaccine efficacy in the past. Recently, a novel bioinformatics approach for assessment of effectiveness of seasonal influenza vaccine was proposed. Here, this approach was used for prediction of the vaccine effectiveness for the influenza season 2017/18 in US.

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Influenza Vaccine Effectiveness in the United States During the 2016–2017 Season

Open Forum Infectious Diseases ◽

10.1093/ofid/ofx163.1151 ◽

2017 ◽

Vol 4 (suppl_1) ◽

pp. S451-S452

Author(s):

Brendan Flannery ◽

Jessie Chung ◽

Arnold S Monto ◽

Emily T Martin ◽

Edward Belongia ◽

...

Keyword(s):

United States ◽

Influenza Vaccine ◽

The United States ◽

Vaccine Effectiveness

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Influenza vaccine effectiveness among patients with high-risk medical conditions in the United States, 2012–2016

Vaccine ◽

10.1016/j.vaccine.2018.10.093 ◽

2018 ◽

Vol 36 (52) ◽

pp. 8047-8053 ◽

Cited By ~ 9

Author(s):

Mei Shang ◽

Jessie R. Chung ◽

Michael L. Jackson ◽

Lisa A. Jackson ◽

Arnold S. Monto ◽

...

Keyword(s):

United States ◽

High Risk ◽

Influenza Vaccine ◽

The United States ◽

Vaccine Effectiveness ◽

Medical Conditions

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150. Relative Effectiveness of High-Dose and Standard-Dose Influenza Vaccine Against Influenza-Related Hospitalization Among Older Adults—United States, 2015–2017

Open Forum Infectious Diseases ◽

10.1093/ofid/ofy209.020 ◽

2018 ◽

Vol 5 (suppl_1) ◽

pp. S10-S10

Author(s):

Joshua Doyle ◽

Lauren Beacham ◽

Elif Alyanak ◽

Manjusha Gaglani ◽

Emily T Martin ◽

...

Keyword(s):

United States ◽

Older Adults ◽

Influenza Vaccine ◽

Influenza A ◽

Standard Dose ◽

Relative Effectiveness ◽

The United States ◽

Vaccine Effectiveness ◽

High Dose ◽

Research Grant

Abstract Background Seasonal influenza causes substantial morbidity and mortality, and older adults are disproportionately affected. Newer vaccines have been developed for use in people 65 years and older, including a trivalent inactivated vaccine with a 4-fold higher dose of antigen (IIV-HD). In recent years, the use of IIV-HD has increased sufficiently to evaluate its effectiveness compared with standard-dose inactivated influenza vaccines (IIV-SD). Methods Hospitalized patients with acute respiratory illness were enrolled in an observational vaccine effectiveness study at 8 hospitals in 4 states participating in the United States Hospitalized Adult Influenza Vaccine Effectiveness Network during the 2015–2016 and 2016–2017 influenza seasons. Predominant influenza A virus subtypes were H1N1 and H3N2, respectively, during these seasons. All enrolled patients were tested for influenza virus with polymerase chain reaction. Receipt and type of influenza vaccine was determined from electronic records and chart review. Odds of laboratory-confirmed influenza were compared among vaccinated and unvaccinated patients. Relative odds of laboratory-confirmed influenza were determined for patients who received IIV-HD or IIV-SD, and adjusted for potential confounding variables via logistic regression. Results Among 1,744 enrolled patients aged ≥ 65 years, 1,105 (63%) were vaccinated; among those vaccinated, 621 (56%) received IIV-HD and 484 (44%) received IIV-SD. Overall, 315 (18%) tested positive for influenza, including 97 (6%) who received IIV-HD, 86 (5%) who received IIV-SD, and 132 (8%) who were unvaccinated. Controlling for age, race, sex, enrollment site, date of illness, index of comorbidity, and influenza season, the adjusted odds of influenza among patients vaccinated with IIV-HD vs. IIV-SD were 0.72 (P = 0.06, 95% CI: 0.52 to 1.01). Conclusion Comparison of high-dose vs. standard-dose vaccine effectiveness during 2 recent influenza seasons (1 H1N1 and 1 H3N2-predominant) suggested relative benefit (nonsignificant) of high-dose influenza vaccine in protecting against influenza-associated hospitalization among persons aged 65 years and older; additional years of data are needed to confirm this finding. Disclosures H. K. Talbot, sanofi pasteur: Investigator, Research grant. Gilead: Investigator, Research grant. MedImmune: Investigator, Research grant. Vaxinnate: Safety Board, none. Seqirus: Safety Board, none.

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1650. Knowledge and Attitudes Toward Influenza Vaccination Among Hispanics: A Survey Conducted in Latin American Consulates in South Florida

Open Forum Infectious Diseases ◽

10.1093/ofid/ofz360.1514 ◽

2019 ◽

Vol 6 (Supplement_2) ◽

pp. S603-S603

Author(s):

Maria L Soler Hidalgo ◽

John M Abbamonte ◽

Laura Regalini ◽

Mariana Schlesinger ◽

Maria L Alcaide ◽

...

Keyword(s):

United States ◽

Health Insurance ◽

Influenza Vaccine ◽

Influenza Vaccination ◽

Latin American ◽

Multinomial Logistic Regression ◽

The United States ◽

South Florida ◽

Knowledge And Attitudes ◽

Hispanic Community

Abstract Background Each year Influenza causes between 12,000 and 56,000 deaths, and over half a million of hospitalizations in the United States. Despite the widespread availability of vaccination, immunization coverage is low. Less than half of American adults receive the influenza vaccine, and there is a disparity between Hispanic and non-Hispanics, with only 35.9% of Hispanic compared with 45.9% of white non-Hispanics receiving the vaccine. In Miami, South Florida, over two-thirds of the population is Hispanic, and rates of influenza vaccination are low. This study aims to identify the knowledge and attitudes toward influenza vaccination among members of the adult Hispanic community in Miami, and to identify barriers to vaccination in this population. Methods This is a cross-sectional study conducted during the influenza season in 2017 and 2019 (October to December). A survey was administered in the waiting rooms of participating Latin American Consulates (Argentina, Colombia, Ecuador, Guatemala, Honduras, Mexico, Peru, and Uruguay) in Miami. Participants included were older than 18 years, Hispanic, and with residence in the United States for more than 6 months. The participants accepted the inform consent orally. The survey was voluntary and anonymous. Results We enrolled 970 adults. The median age was 43 years, 50% were male, 60% had health insurance, and 67% had completed education of high school or higher. Knowledge regarding influenza and vaccination was low (78% believed asymptomatic individuals could transmit influenza, 14% knew that vaccination is recommended during the winter months, 50% felt not everyone should be vaccinated, 25% believed the vaccine causes influenza, and 7% autism). About one quarter (27%) received the influenza vaccine annually, 35% sometimes, and 38% never. Using multinomial logistic regression, we identified age χ2(2) = 19.38, P < 0.001, consulate χ2(6) = 160.21, P < 0.001, and insurance status χ2(2) = 23.04, P < 0.001 as predictors of receiving vaccination. Neither gender, nor education level found to be associated with vaccination behavior. Conclusion Immunization rates in the adult Hispanic population are low. Interventions to improve vaccination among Hispanics who are older and lack of health insurance are urgently needed in the diverse Hispanic community. Disclosures All authors: No reported disclosures.

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