Comparison of Parental Report of Influenza Vaccination to Documented Records in Children Hospitalized With Acute Respiratory Illness, 2015–2016

Abstract Background Parent-reported influenza vaccination history may be valuable clinically and in influenza vaccine effectiveness (VE) studies. Few studies have assessed the validity of parental report among hospitalized children. Methods Parents of 2597 hospitalized children 6 months–17 years old were interviewed from November 1, 2015 to June 30, 2016, regarding their child’s sociodemographic and influenza vaccination history. Parent-reported 2015–2016 influenza vaccination history was compared with documented vaccination records (considered the gold standard for analysis) obtained from medical records, immunization information systems, and providers. Multivariable logistic regression analyses were conducted to determine potential factors associated with discordance between the 2 sources of vaccination history. Using a test-negative design, we estimated VE using vaccination history obtained through parental report and documented records. Results According to parental report, 1718 (66%) children received the 2015–2016 influenza vaccine, and of those, 1432 (83%) had documentation of vaccine receipt. Percent agreement was 87%, with a sensitivity of 96% (95% confidence interval [CI], 95%–97%) and a specificity of 74% (95% CI, 72%–77%). In the multivariable logistic regression, study site and child’s age 5–8 years were significant predictors of discordance. Adjusted VE among children who received ≥1 dose of the 2015–2016 influenza vaccine per parental report was 61% (95% CI, 43%–74%), whereas VE using documented records was 55% (95% CI, 33%–69%). Conclusions Parental report of influenza vaccination was sensitive but not as specific compared with documented records. However, VE against influenza-associated hospitalizations using either source of vaccination history did not differ substantially. Parental report is valuable for timely influenza VE studies.

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2738. Influenza Vaccination During Pregnancy Among Mothers of Infants with Acute Respiratory Illness, United States, 2016–2018

Open Forum Infectious Diseases ◽

10.1093/ofid/ofz360.2416 ◽

2019 ◽

Vol 6 (Supplement_2) ◽

pp. S963-S964

Author(s):

Constance E Ogokeh ◽

Manish Patel ◽

Joana Y Lively ◽

Mary A Staat ◽

Geoffrey A Weinberg ◽

...

Keyword(s):

Influenza Vaccine ◽

Influenza Vaccination ◽

Pregnant Women ◽

Influenza Season ◽

Respiratory Illness ◽

Vaccine Safety ◽

Acute Respiratory Illness ◽

Surveillance Network ◽

Vaccination History ◽

Maternal Influenza

Abstract Background Influenza vaccination has been shown to reduce influenza risk in pregnant women and their infants who are not yet age-eligible for vaccine. Ascertainment of vaccination history is important for vaccine safety and effectiveness evaluations. Our goals were to (a) determine coverage, location, and timing of maternal influenza vaccination and (b) compare a subset of self-reported influenza vaccinations with documented vaccine records. Methods We enrolled children < 18 years. with acute respiratory illness in 7 pediatric hospitals and emergency departments in the New Vaccine Surveillance Network from December 1, 2016 to October 31, 2018. We interviewed all mothers of enrolled infants < 1 year, and obtained mother’s influenza vaccine information while pregnant. As an option, sites obtained maternal influenza vaccine records from reported sources (e.g., registries, provider records, pharmacies). Results Among 5,458 mothers, 2,944 (54%) self-reported receiving influenza vaccine during pregnancy (57% in 2016–2017; 51% in 2017–2018), varying from 49% to 74% by site. Among self-reported vaccinees, 17%, 36%, and 47% received vaccine during their first, second, and third trimester, respectively. Most women (76%) were vaccinated at their OB/GYN or midwife office, 7% at their primary care provider, 7% at their workplace, and 5% at a retail pharmacy. Among 1,338 infants < 6 months. during early influenza season (i.e., born from June to August) and thus ineligible for vaccination, only 46% of mothers reported receiving vaccine during pregnancy (42% reported not receiving it, 12% were unsure). Of 2,242 women for whom vaccine verification was attempted, 1,491 (67%) self-reported receiving influenza vaccine during pregnancy; of those, documentation of vaccine receipt was found for 901 (60%). Conclusion Influenza vaccination coverage among pregnant women was suboptimal, potentially increasing the risk of influenza in unvaccinated pregnant women. Infants born to unvaccinated women, particularly those born from June to August, may also be at higher risk since they are not age-eligible to receive vaccine before influenza season. The optimal approach to ascertainment of maternal vaccination history with accuracy and completeness merits further investigation. Disclosures All authors: No reported disclosures.

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22. Description of Hospitalized Patients with Influenza Vaccine Failure

Open Forum Infectious Diseases ◽

10.1093/ofid/ofaa439.067 ◽

2020 ◽

Vol 7 (Supplement_1) ◽

pp. S35-S35

Author(s):

Joanna Kimball ◽

Yuwei Zhu ◽

Dayna Wyatt ◽

Helen Talbot

Keyword(s):

Logistic Regression ◽

Influenza Vaccine ◽

Influenza Vaccination ◽

Older Patients ◽

Influenza A ◽

Influenza Season ◽

Hospitalized Patients ◽

Vaccine Failure ◽

Increased Risk ◽

Immunosuppressed Patients

Abstract Background Despite influenza vaccination, some patients develop illness and require hospitalization. Many factors contribute to vaccine failure, including mismatch of the vaccine and circulating strains, waning immunity, timing of influenza season, age and patient comorbidities such as immune function. This study compared vaccinated, hospitalized patients with and without influenza. Methods This study used 2015–2019 Tennessee data from the US Hospitalized Adult Influenza Vaccine Effectiveness Network database. Enrolled patients were ≥ 18 years vaccinated for the current influenza season and admitted with an acute respiratory illness. Patient or surrogate interviews and medical chart abstractions were performed, and influenza vaccinations were confirmed by vaccine providers. Influenza PCR testing was performed in a research lab. Statistical analyses were performed with STATA and R using Pearson’s chi-squared, Kruskal-Wallis and Wilcoxon rank-sum tests and multivariate logistic regression. Results 1236 patients met study criteria, and 235 (19%) tested positive for influenza. Demographics, vaccines and comorbidities were similar between the two groups (Table 1) except for morbid obesity, which was more common in influenza negative patients (13% vs 8%, p = 0.04), and immunosuppression, which was more common in the influenza positive (63% vs 54%, p = 0.01). Logistic regression analysis demonstrated older patients (OR 1.47, 95% CI 1.03–2.10) and immunosuppressed patients (OR 1.56, 1.15–2.12) were at increased risk for influenza (Table 2 and Figure 1). Immunosuppression also increased the risk for influenza A/H3N2 (OR 1.86, 95% CI 1.25–2.75). A sensitivity analysis was performed on patients who self-reported influenza vaccination for the current season without vaccine verification and demonstrated increased risk of influenza in older adults (OR 1.66, 95% CI 1.16–2.39). Table 1: Demographics of influenza positive versus influenza negative patients in influenza vaccinated, hospitalized patients. Table 2: Logistic regression analyses of vaccinated, hospitalized influenza positive patients; vaccinated, hospitalized patients with influenza A subtypes and self-reported vaccinated, hospitalized influenza positive patients. Figure 1: Predicted Probability of Hospitalization with Influenza, Influenza A/H1N1 and Influenza A/H3N2 in Vaccinated Patients by Age. Conclusion Our study demonstrated an increased risk of influenza vaccine failure in older patients and immunosuppressed patients. These groups are also at increased risk for influenza complications. To improve protection of these patients against future influenza illnesses, more effective vaccines are needed, and more research on ring vaccination should be pursued. Disclosures All Authors: No reported disclosures

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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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The Effect of Influenza Vaccination History on Changes in Hemagglutination Inhibition Titers After Receipt of the 2015–2016 Influenza Vaccine in Older Adults in Hong Kong

The Journal of Infectious Diseases ◽

10.1093/infdis/jiz327 ◽

2019 ◽

Vol 221 (1) ◽

pp. 33-41 ◽

Cited By ~ 1

Author(s):

Tiffany W Y Ng ◽

Ranawaka A P M Perera ◽

Vicky J Fang ◽

Emily M Yau ◽

J S Malik Peiris ◽

...

Keyword(s):

Older Adults ◽

Hong Kong ◽

Influenza Vaccine ◽

Influenza Vaccination ◽

Hemagglutination Inhibition ◽

Age Groups ◽

Antibody Responses ◽

Serum Samples ◽

Vaccination History ◽

Antibody Titers

Abstract Background Immune responses to influenza vaccination can be weaker in older adults than in other age groups. We hypothesized that antibody responses would be particularly weak among repeat vaccinees when the current and prior season vaccine components are the same. Methods An observational study was conducted among 827 older adults (aged ≥75 years) in Hong Kong. Serum samples were collected immediately before and 1 month after receipt of the 2015–2016 quadrivalent inactivated influenza vaccine. We measured antibody titers with the hemagglutination inhibition assay and compared the mean fold rise from prevaccination to postvaccination titers and the proportions with postvaccination titers ≥40 or ≥160. Results Participants who reported receipt of vaccination during either of the previous 2 years had a lower mean fold rise against all strains than with those who did not. Mean fold rises for A(H3N2) and B/Yamagata were particularly weak after repeated vaccination with the same vaccine strain, but we did not generally find significant differences in the proportions of participants with postvaccination titers ≥40 and ≥160. Conclusions Overall, we found that reduced antibody responses in repeat vaccinees were particularly reduced among older adults who had received vaccination against the same strains in preceding years.

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Vaccine effectiveness against influenza-associated hospitalization among children aged < 13 years using a hospital-based surveillance system in Minnesota, 2013 – 2016

Open Forum Infectious Diseases ◽

10.1093/ofid/ofx162.142 ◽

2017 ◽

Vol 4 (suppl_1) ◽

pp. S60-S60

Author(s):

Ashley Fowlkes ◽

Hannah Friedlander ◽

Andrea Steffens ◽

Kathryn Como-Sabetti ◽

Dave Boxrud ◽

...

Keyword(s):

Influenza Vaccine ◽

Influenza Vaccination ◽

Influenza A ◽

Respiratory Illness ◽

Vaccine Effectiveness ◽

Influenza Viruses ◽

Point Estimate ◽

Influenza B ◽

Current Season ◽

Immunization Registry

Abstract Background Due to marked variability in circulating influenza viruses each year, annual evaluation of the vaccine’s effectiveness against severe outcomes is essential. We used the Minnesota Department of Health’s (MDH) Severe Acute Respiratory Illness (SARI) surveillance to evaluate vaccine effectiveness (VE) against influenza-associated hospitalization over three influenza seasons. Methods Residual respiratory specimens from patients admitted with SARI were sent to the MDH laboratory for influenza RT-PCR testing. Medical records were reviewed to collect patient data. Vaccination history was verified using the state immunization registry. We included patients aged ≥6 months to < 13 years, after which immunization reporting is not required, hospitalized from the earliest influenza detection after July through April each year. We defined vaccinated patients as those ≥1 dose of influenza vaccine in the current season. Children aged < 9 years with no history of vaccination were considered vaccinated if 2 were doses given a month apart. Partially vaccinated children were excluded. We estimated VE as 1 minus the adjusted odds ratio (x100%) of influenza vaccination among influenza cases vs. negative controls, controlling for age, race, days from onset to admission, comorbidities, and admission month. Results Among 2198 SARI patients, 763 (35%) were vaccinated for influenza, 180 (8.2%) were partially vaccinated, and 1255 (57%) were unvaccinated. Influenza was detected among 202 (9.2%) children, and significantly more frequently among children aged ≥5 years (17%) compared with younger children (7.4%). The adjusted VE in 2013–14 was 68% (95% Confidence Interval: 34, 85), but was non-significant during the 2014–15 and 2015–16 seasons (Figure). Estimates of VE by influenza A subtypes varied substantially by year; VE against influenza B viruses was significant, but could not be stratified by year. VE was impacted when live attenuated influenza vaccine recipients were excluded. Conclusion We report moderately high influenza VE in 2013–14 and a point estimate higher than other published estimates from outpatient data in 2014–15. These results, underscore the importance of influenza vaccination to prevent severe outcomes such as hospitalization. Disclosures All authors: No reported disclosures.

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Determinants of influenza vaccine uptake and willingness to be vaccinated by pharmacists among the active adult population in Hungary: a cross-sectional exploratory study

BMC Public Health ◽

10.1186/s12889-021-10572-8 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Githa Fungie Galistiani ◽

Mária Matuz ◽

Nikolett Matuszka ◽

Péter Doró ◽

Krisztina Schváb ◽

...

Keyword(s):

Logistic Regression ◽

Risk Factor ◽

Influenza Vaccine ◽

Health Risk ◽

Influenza Vaccination ◽

Influenza Season ◽

Adult Population ◽

Vaccine Uptake ◽

Cross Sectional ◽

Vaccination Uptake

Abstract Background Many studies have addressed influenza vaccine uptake in risk-group populations (e.g. the elderly). However, it is also necessary to assess influenza vaccine uptake in the active adult population, since they are considered to be a high-transmitter group. In several countries pharmacists are involved in adult vaccination in order to increase uptake. This study therefore aimed to investigate the determinants of influenza vaccination uptake and examine the willingness to be vaccinated by pharmacists. Methods A cross-sectional study was conducted among Hungarian adults using a self-administered online questionnaire distributed via social media (Facebook). The questionnaire included five domains: demographics, vaccine uptake, factors that motivated or discouraged vaccination, knowledge and willingness of participants to accept pharmacists as influenza vaccine administrators. Descriptive statistics were applied and logistic regression was conducted to assess the possible determinants of vaccination uptake. Results Data from 1631 participants who completed the questionnaires were analysed. Almost 58% of respondents (944/1631) had occupational and/or health risk factors for influenza. Just over one-tenth (12.3%;200/1631) of participants were vaccinated during the 2017/18 influenza season, 15.4% (145/944) of whom had a risk factor for influenza. Approximately half of the participants (47.4%) believed that influenza vaccination can cause flu, and just over half of them (51.6%), were not knowledgeable about the safety of influenza vaccine ingredients. Logistic regression found that age, sex, health risk factor and knowledge on influenza/influenza vaccination were associated with influenza vaccination uptake (p < 0.05). The most frequently cited reason for having an influenza vaccination was self-protection (95.0%). The most common reason given for refusing the influenza vaccine was that the respondent stated they rarely had an infectious disease (67.7%). The number of participants who were willing to be vaccinated by pharmacists was two-times higher than the number of participants who were actually vaccinated during the 2017/18 influenza season. Conclusion Influenza vaccine uptake in the active adult population is low in Hungary. Public awareness and knowledge about influenza vaccination and influenza disease should be increased. The results also suggest a need to extend the role played by pharmacists in Hungary.

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Effectiveness of influenza vaccination in elderly outpatients in São Paulo city, Brazil

Revista do Instituto de Medicina Tropical de São Paulo ◽

10.1590/s0036-46652001000600003 ◽

2001 ◽

Vol 43 (6) ◽

pp. 317-320 ◽

Cited By ~ 11

Author(s):

Eliana Battaggia GUTIERREZ ◽

Ho Yeh LI ◽

Ana Catarina De Seixas SANTOS ◽

Marta Heloísa LOPES

Keyword(s):

Influenza Vaccine ◽

Influenza Vaccination ◽

Respiratory Illness ◽

The Elderly ◽

Sao Paulo ◽

Lower Number ◽

São Paulo ◽

Influenza Like Illness ◽

Elderly Outpatients ◽

Health Situation

To investigate the effectiveness of the influenza vaccine in a population of elderly outpatients, we compared the occurrence and frequency of influenza like illness (ILI), respiratory illness and hospitalization in vaccinated and non-vaccinated subjects. All the outcomes were clinically defined. The two groups were similar with respect to demographics, health situation and habits. The influenza vaccine contributed to the protection of the elderly investigated, since the vaccinated subjects referred a significantly lower number of ILI than the non-vaccinated. There is a need for more studies about the effectiveness of the influenza vaccine in our country in elderly and other groups of our population.

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Hubungan Jenis Persalinan dan Prematuritas dengan Hiperbilirubinemia di RS Persahabatan

Jurnal Vokasi Indonesia ◽

10.7454/jvi.v1i1.8 ◽

2013 ◽

Vol 1 (1) ◽

Author(s):

Elsa Roselina ◽

Saroha Pinem ◽

Rochimah Rochimah

Keyword(s):

Logistic Regression ◽

Statistical Analysis ◽

Research Design ◽

Medical Records ◽

Odds Ratio ◽

Case Control ◽

P Value ◽

Maternal Factor ◽

Multivariable Logistic Regression

ABSTRACT. Hyperbilirubinemia refers to an excessive level of accumulated bilirubin in the blood and ischaracterized by jaundice, or icterus, a yellowish discoloration of the skin and other organs. There are two riskfactors that related to hyperbilirubinemia. Those factors are maternal factor and neonates‟ factor. The aim ofthis research knew which variables which catagorized as maternal factor and neonates‟ factor that related tohyperbilirubinemia in Persahabatan hospital. This research used medical records from 216 neonates andhis/her mother from October 2008 until October 2009 as samples. Research design was case control, with used5% level of significant and 80% power. The statistical analysis was multivariable logistic regression. Factorsthat related to hyperbilirubinemia in Persahabatan hospital were type of labor (p value 0.000) andprematurity (p value 0.022). Type of labor is a dominant variable that related to hyperbilirubinemia andneonates from un-spontaneous labor has probability to be hyperbilirubinemia 50.193 times than neonates fromspontaneous labor after controlled by prematurity (odds ratio 50.193).Keywords: hyperbilirubinemia, type of labor, prematurity

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2062. Improving Antibiotic Prescribing in the Ambulatory Care Setting—Stewardship through Influenza Vaccination, US Flu VE Network 2013–2014 Through 2017–2018

Open Forum Infectious Diseases ◽

10.1093/ofid/ofz360.1742 ◽

2019 ◽

Vol 6 (Supplement_2) ◽

pp. S695-S695

Author(s):

Emily Smith ◽

Alicia M. Fry ◽

Lauri Hicks ◽

Katherine E Fleming-Dutra ◽

Emily T Martin ◽

...

Keyword(s):

Antibiotic Resistance ◽

Influenza Vaccine ◽

Influenza Vaccination ◽

Vaccine Coverage ◽

Improve Patient Safety ◽

Respiratory Illness ◽

Antibiotic Use ◽

The United States ◽

Antibiotic Prescribing ◽

Ambulatory Care Setting

Abstract Background Improving antibiotic use is a key strategy to combat antibiotic resistance and improve patient safety. Acute respiratory illness (ARI) is a common cause of outpatient visits and accounts for ~41% of antibiotics used in the United States. We sought to determine the proportion of antibiotic prescriptions (Rx) prescribed among outpatients with ARI that can be potentially averted through influenza vaccination. Methods From 2013–2014 through 2017–2018 influenza seasons, we enrolled patients aged ≥6 months with ARI in the US Influenza Vaccine Effectiveness (VE) Network of >50 outpatient clinics. Antibiotic Rx and diagnosis codes were collected from medical records. Study influenza test results were not available to treating clinicians at most sites, and clinical influenza testing was infrequently performed (a), prevalence of influenza among unvaccinated ARI patients (b), prevalence of antibiotic Rx among unvaccinated influenza-positive ARI patients (c) and prevalence of antibiotic Rx among ARI patients overall (d), we derived estimates of the proportion of ARI antibiotic Rx that can be averted by influenza vaccination [(a × b × c)/d]. Results Among 37487 outpatients with ARI, 13,316 (36%) were prescribed an antibiotic and 9,689 (26%) tested positive for influenza. Of those positive, 2,496 (26%) were prescribed an antibiotic. Adjusted VE against influenza-associated ARI was 35% (95% confidence interval (CI), 32 to 39). Among unvaccinated patients with ARI, 30% were influenza-positive and 24% received antibiotics. Based on these estimates, we determined that influenza vaccination may prevent 10.6% of all ARI syndromes and may avert 1 in 14 or 7.3% of antibiotic Rx among ARI patients. Conclusion By preventing influenza-associated ARI syndromes, influenza vaccination may substantially reduce antibiotic prescribing. Increasing influenza vaccine coverage and improving protection may facilitate national goals to improve antibiotic use and reduce the global threat of antibiotic resistance. Disclosures All authors: No reported disclosures.

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2739. Comparison of Hemagglutination Antibody Inhibition (HAI) Titers Following Influenza Vaccination by Birth Cohort and Repeated Influenza Vaccination History

Open Forum Infectious Diseases ◽

10.1093/ofid/ofz360.2417 ◽

2019 ◽

Vol 6 (Supplement_2) ◽

pp. S964-S964

Author(s):

Amy C Sherman ◽

Lilin Lai ◽

Mary B Bower ◽

Muktha S Natrajan ◽

Christopher M Huerta ◽

...

Keyword(s):

Influenza Vaccine ◽

Influenza Vaccination ◽

Birth Cohort ◽

Geometric Mean ◽

Fold Change ◽

Post Vaccination ◽

The Past ◽

Significant Difference ◽

Vaccination History ◽

Research Grant

Abstract Background The host immune response to influenza vaccination can be affected by prior imprinting to a specific influenza strain based on birth cohort and prior influenza vaccination history. Understanding the underlying immune mechanisms is essential to development of an improved seasonal vaccine and an effective universal influenza vaccine. Methods This is a prospective pilot study, with a total of 20 subjects in either the H3N2 cohort (N = 10, born 1968–1977) or the H1N1 cohort (N = 10, born 1948–1957). Each cohort was further stratified by subjects who have received the influenza vaccine < 2 or ≥ 3 of the past 5 years. The FDA-approved quadrivalent 2018–19 influenza vaccine (containing A(H1N1), an A/Michigan/45/2015-like virus; A(H3N2), an A/Singapore/INFIMH-16–0019/2016-like virus; B/Colorado/06/2017-like virus; and B/Phuket/3073/2013-like virus) was administered on Day 1. Demographic information included age, gender, ethnicity, and BMI. HAI titers for each component of the vaccine were obtained at baseline, 29 days post-vaccination, and 180 days post-vaccination. HAI fold-change and HAI geometric mean titers (GMT) were analyzed. Results There was no significant difference between H1N1 or H3N2 HAI fold-change in the H3N2 birth cohort (P = 0.7496) or in the H1N1 birth cohort (P = 0.8237), Figure A. Comparing HAI fold-change for the repeatedly vs. minimally vaccinated groups, there was a significant higher fold change in the minimally vaccinated group (H1N1 HAI (P = 0.002) and H3N2 HAI (P < 0.0001), Figure B). GMT was higher at baseline for the repeatedly vaccinated group (H1N1, 70; H3N2, 98; vs. H1N1, 30; H3N2, 21 for the minimally vaccinated group); however, the GMT for the minimally vaccinated group was higher at day 29 (H1N1, 172; H3N2, 184; vs. H1N1, 422; H3N2, 299 for the minimally vaccinated group; Figure C). HAI titers and analysis at day 180 post vaccination are in progress. Conclusion There was no evidence of an imprinting effect by birth cohort for HAI titer magnitudes, even when stratified by vaccination history. There was a significantly higher HAI fold change for individuals who had received minimal influenza vaccinations in the past 5 years at 29 days post-vaccination. Individuals who had repeated vaccinations in the last 5 years had higher HAI GMT at baseline. Disclosures Nadine Rouphael, MD, Merck: I conduct as Emory PI the PNEUMO MERCK study at Emory, Research Grant; Pfizer: I conduct as co-PI the RSV PFIZER study at Emory, Research Grant; Sanofi-Pasteur: I conducted as Emory PI the CDIFFENSE trial at Emory, Research Grant.

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