Patient and immunological factors associated with delayed clearance of mucosal SARS-CoV-2 RNA and symptom persistence.

Serial blood and mucosal samples were characterized for 102 participants enrolled a median of 7.0 days post-COVID-19 diagnosis. Mucosal RNA was detectable a median 31.5 (95% CI 20.5 - 63.5) days, with persistence ≥1 month associated with obesity (BMI ≥30, OR 3.9, 95% CI 1.2 - 13.8) but not age, sex, or chronic conditions. Fifteen participants had likely reinfection; lower serum anti-S IgG levels were associated with reinfection risk. Nearly half of participants (47%) reported symptoms lasting ≥2-3 months; persistence ≥3 months was associated with BMI ≥30 (OR = 4.2 95% CI 1.1 - 12.8) and peak anti-S and anti-NC antibody levels.

Prevalence of SARS-CoV-2 Viremia in Presymptomatic Blood Donors in the Delta and Omicron Variant Eras.

Presymptomatic plasma samples from 1596 donors reporting coronavirus disease 2019 infection or symptoms after blood donation were tested for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA and anti-S and anti-N antibodies. Prior infection and vaccination both protected from developing SARS-CoV-2 RNAemia and from symptomatic infection. RNAemia rates did not differ in the Delta and Omicron variant eras.

Patient and Epidemiological Factors Associated With Influenza Testing in Hospitalized Adults With Acute Respiratory Illnesses, 2016-2017 to 2019-2020.

Background: Data are limited on influenza testing among adults with acute respiratory illness (ARI)-associated hospitalizations. We identified factors associated with influenza testing in adult ARI-associated hospitalizations across the 2016-2017 through 2019-2020 influenza seasons. Methods: Using data from 4 health systems in the United States, we identified hospitalizations that had an ARI discharge diagnosis or respiratory virus test. A hospitalization with influenza testing was based on testing performed within 14 days before through 72 hours after admission. We used random forest analysis to identify patient characteristics and influenza activity indicators that were most important in terms of their relationship to influenza testing. Results: Across 4 seasons, testing rates ranged from 14.8%-19.4% at 3 pooled sites and 60.1%-78.5% at a fourth site with different testing practices. Discharge diagnoses of pneumonia or infectious disease of noninfluenza etiology, presence of ARI signs/symptoms, hospital admission month, and influenza-like illness activity level were consistently among the variables with the greatest relative importance. Conclusions: Select ARI diagnoses and indicators of influenza activity were the most important factors associated with influenza testing among ARI-associated hospitalizations. Improved understanding of which patients are tested may enhance influenza burden estimates and allow for more timely clinical management of influenza-associated hospitalizations.

Accuracy of COVID-19-Like Illness Diagnoses in Electronic Health Record Data: Retrospective Cohort Study.

BACKGROUND: Electronic health record (EHR) data provide a unique opportunity to study the epidemiology of COVID-19, clinical outcomes of the infection, comparative effectiveness of therapies, and vaccine effectiveness but require a well-defined computable phenotype of COVID-19-like illness (CLI). OBJECTIVE: The objective of this study was to evaluate the performance of pathogen-specific and other acute respiratory illness (ARI) International Statistical Classification of Diseases-9 and -10 codes in identifying COVID-19 cases in emergency department (ED) or urgent care (UC) and inpatient settings. METHODS: We conducted a retrospective observational cohort study using EHR, claims, and laboratory information system data of ED or UC and inpatient encounters from 4 health systems in the United States. Patients who were aged ≥18 years, had an ED or UC or inpatient encounter for an ARI, and underwent a SARS-CoV-2 polymerase chain reaction test between March 1, 2020, and March 31, 2021, were included. We evaluated various CLI definitions using combinations of International Statistical Classification of Diseases-10 codes as follows: COVID-19-specific codes; CLI definition used in VISION network studies; ARI signs, symptoms, and diagnosis codes only; signs and symptoms of ARI only; and random forest model definitions. We evaluated the sensitivity, specificity, positive predictive value, and negative predictive value of each CLI definition using a positive SARS-CoV-2 polymerase chain reaction test as the reference standard. We evaluated the performance of each CLI definition for distinct hospitalization and ED or UC cohorts. RESULTS: Among 90,952 hospitalizations and 137,067 ED or UC visits, 5627 (6.19%) and 9866 (7.20%) were positive for SARS-CoV-2, respectively. COVID-19-specific codes had high sensitivity (91.6%) and specificity (99.6%) in identifying patients with SARS-CoV-2 positivity among hospitalized patients. The VISION CLI definition maintained high sensitivity (95.8%) but lowered specificity (45.5%). By contrast, signs and symptoms of ARI had low sensitivity and positive predictive value (28.9% and 11.8%, respectively) but higher specificity and negative predictive value (85.3% and 94.7%, respectively). ARI diagnoses, signs, and symptoms alone had low predictive performance. All CLI definitions had lower sensitivity for ED or UC encounters. Random forest approaches identified distinct CLI definitions with high performance for hospital encounters and moderate performance for ED or UC encounters. CONCLUSIONS: COVID-19-specific codes have high sensitivity and specificity in identifying adults with positive SARS-CoV-2 test results. Separate combinations of COVID-19-specific codes and ARI codes enhance the utility of CLI definitions in studies using EHR data in hospital and ED or UC settings.

Frequent detection but lack of infectivity of SARS-CoV-2 RNA in presymptomatic, infected blood donor plasma.

Respiratory viruses such as influenza do not typically cause viremia; however, SARS-CoV-2 has been detected in the blood of COVID-19 patients with mild and severe symptoms. Detection of SARS-CoV-2 in blood raises questions about its role in pathogenesis as well as transfusion safety concerns. Blood donor reports of symptoms or a diagnosis of COVID-19 after donation (post-donation information, PDI) preceded or coincided with increased general population COVID-19 mortality. Plasma samples from 2,250 blood donors who reported possible COVID-19-related PDI were tested for the presence of SARS-CoV-2 RNA. Detection of RNAemia peaked at 9%-15% of PDI donors in late 2020 to early 2021 and fell to approximately 4% after implementation of widespread vaccination in the population. RNAemic donors were 1.2- to 1.4-fold more likely to report cough or shortness of breath and 1.8-fold more likely to report change in taste or smell compared with infected donors without detectable RNAemia. No infectious virus was detected in plasma from RNAemic donors; inoculation of permissive cell lines produced less than 0.7-7 plaque-forming units (PFU)/mL and in susceptible mice less than 100 PFU/mL in RNA-positive plasma based on limits of detection in these models. These findings suggest that blood transfusions are highly unlikely to transmit SARS-CoV-2 infection.

Population-Weighted Seroprevalence From Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Infection, Vaccination, and Hybrid Immunity Among US Blood Donations From January to December 2021.

BACKGROUND: Previous severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and coronavirus disease 2019 (COVID-19) vaccination, independently and combined ("hybrid immunity"), result in partial protection from subsequent infection and strong protection from severe disease. Proportions of the US population who have been infected, vaccinated, or have hybrid immunity remain unclear, posing a challenge for assessing effective pandemic mitigation strategies. METHODS: In this serial cross-sectional study, nationwide blood donor specimens collected during January-December 2021 were tested for anti-spike and anti-nucleocapsid antibodies, and donor COVID-19 vaccination history of ≥1 dose was collected. Monthly seroprevalence induced from SARS-CoV-2 infection, COVID-19 vaccination, or both, were estimated. Estimates were weighted to account for demographic differences from the general population and were compared temporally and by demographic factors. RESULTS: Overall, 1 123 855 blood samples were assayed. From January to December 2021, the weighted percentage of donations with seropositivity changed as follows: seropositivity due to vaccination without previous infection, increase from 3.5% (95% confidence interval, 3.4%-3.7%) to 64.0%, (63.5%-64.5%); seropositivity due to previous infection without vaccination, decrease from 15.6% (15.2%-16.0%) to 11.7% (11.4%-12.0%); and seropositivity due to hybrid immunity, increase from 0.7% (0.6%-0.7%) to 18.9% (18.5%-19.3%). Combined seroprevalence from infection, vaccination, or both increased from 19.8% (19.3%-20.2%) to 94.5% (93.5%-94.0%). Infection- and vaccination-induced antibody responses varied significantly by age, race-ethnicity, and region, but not by sex. CONCLUSIONS: Our results indicate substantial increases in population humoral immunity from SARS-CoV-2 infection, COVID-19 vaccination, and hybrid immunity during 2021. These findings are important to consider in future COVID-19 studies and long-term pandemic mitigation efforts.

How do we form and coordinate a national serosurvey of SARS-CoV-2 within the blood collection industry?

BACKGROUND: A national serosurvey of U.S. blood donors conducted in partnership with the Centers for Disease Control and Prevention (CDC) was initiated to estimate the prevalence of SARS-CoV-2 infections and vaccinations. METHODS: Beginning in July 2020, the Nationwide Blood Donor Seroprevalence Study collaborated with multiple blood collection organizations, testing labs, and leadership from government partners to capture, test, and analyze approximately 150,000 blood donation specimens per month in a repeated, cross-sectional seroprevalence survey. RESULTS: A CDC website (https://covid.cdc.gov/covid-data-tracker/#nationwide-blood-donor-seroprevalence) provided stratified, population-level results to public health professionals and the general public. DISCUSSION: The study adapted operations as the pandemic evolved, changing specimen flow and testing algorithms, and collecting additional data elements in response to changing policies on universal blood donation screening and administration of SARS-CoV-2 spike-based vaccines. The national serosurvey demonstrated the utility of serosurveillance testing of residual blood donations and highlighted the role of the blood collection industry in public-private partnerships during a public health emergency.

Use of US Blood Donors for National Serosurveillance of Severe Acute Respiratory Syndrome Coronavirus 2 Antibodies: Basis for an Expanded National Donor Serosurveillance Program.

BACKGROUND: The Recipient Epidemiology and Donor Evaluation Study-IV-Pediatric (REDS-IV-P) Epidemiology, Surveillance and Preparedness of the Novel SARS-CoV-2 Epidemic (RESPONSE) seroprevalence study conducted monthly cross-sectional testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies in blood donors in 6 US metropolitan regions to estimate the extent of SARS-CoV-2 infections over time. METHODS: During March-August 2020, approximately ≥1000 serum specimens were collected monthly from each region and tested for SARS-CoV-2 antibodies using a well-validated algorithm. Regional seroprevalence estimates were weighted based on demographic differences compared with the general population. Seroprevalence was compared with reported coronavirus disease 2019 (COVID-19) case rates over time. RESULTS: For all regions, seroprevalence was <1.0% in March 2020. New York, New York, experienced the biggest increase (peak seroprevalence, 15.8% in May). All other regions experienced modest increases in seroprevalence (1%-2% in May-June to 2%-4% in July-August). Seroprevalence was higher in younger, non-Hispanic black, and Hispanic donors. Temporal increases in donor seroprevalence correlated with reported case rates in each region. In August, 1.3-5.6 estimated cumulative infections (based on seroprevalence data) per COVID-19 case were reported to the Centers for Disease Control and Prevention. CONCLUSIONS: Increases in seroprevalence were found in all regions, with the largest increase in New York. Seroprevalence was higher in non-Hispanic black and Hispanic than in non-Hispanic white blood donors. SARS-CoV-2 antibody testing of blood donor samples can be used to estimate the seroprevalence in the general population by region and demographic group. The methods derived from the RESPONSE seroprevalence study served as the basis for expanding SARS-CoV-2 seroprevalence surveillance to all 50 states and Puerto Rico.

Estimated US Infection- and Vaccine-Induced SARS-CoV-2 Seroprevalence Based on Blood Donations, July 2020-May 2021.

Importance: People who have been infected with or vaccinated against SARS-CoV-2 have reduced risk of subsequent infection, but the proportion of people in the US with SARS-CoV-2 antibodies from infection or vaccination is uncertain. Objective: To estimate trends in SARS-CoV-2 seroprevalence related to infection and vaccination in the US population. Design, Setting, and Participants: In a repeated cross-sectional study conducted each month during July 2020 through May 2021, 17 blood collection organizations with blood donations from all 50 US states; Washington, DC; and Puerto Rico were organized into 66 study-specific regions, representing a catchment of 74% of the US population. For each study region, specimens from a median of approximately 2000 blood donors were selected and tested each month; a total of 1 594 363 specimens were initially selected and tested. The final date of blood donation collection was May 31, 2021. Exposure: Calendar time. Main Outcomes and Measures: Proportion of persons with detectable SARS-CoV-2 spike and nucleocapsid antibodies. Seroprevalence was weighted for demographic differences between the blood donor sample and general population. Infection-induced seroprevalence was defined as the prevalence of the population with both spike and nucleocapsid antibodies. Combined infection- and vaccination-induced seroprevalence was defined as the prevalence of the population with spike antibodies. The seroprevalence estimates were compared with cumulative COVID-19 case report incidence rates. Results: Among 1 443 519 specimens included, 733 052 (50.8%) were from women, 174 842 (12.1%) were from persons aged 16 to 29 years, 292 258 (20.2%) were from persons aged 65 years and older, 36 654 (2.5%) were from non-Hispanic Black persons, and 88 773 (6.1%) were from Hispanic persons. The overall infection-induced SARS-CoV-2 seroprevalence estimate increased from 3.5% (95% CI, 3.2%-3.8%) in July 2020 to 20.2% (95% CI, 19.9%-20.6%) in May 2021; the combined infection- and vaccination-induced seroprevalence estimate in May 2021 was 83.3% (95% CI, 82.9%-83.7%). By May 2021, 2.1 SARS-CoV-2 infections (95% CI, 2.0-2.1) per reported COVID-19 case were estimated to have occurred. Conclusions and Relevance: Based on a sample of blood donations in the US from July 2020 through May 2021, vaccine- and infection-induced SARS-CoV-2 seroprevalence increased over time and varied by age, race and ethnicity, and geographic region. Despite weighting to adjust for demographic differences, these findings from a national sample of blood donors may not be representative of the entire US population.

An international cohort study of birth outcomes associated with hospitalized acute respiratory infection during pregnancy.

OBJECTIVES: Findings during the 2009 pandemic suggest severe maternal infection with pandemic influenza had adverse perinatal health consequences. Limited data exist evaluating the perinatal health effects of severe seasonal influenza and non-influenza infections during pregnancy. METHODS: A retrospective cohort of pregnant women from Australia, Canada, Israel, and the United States was established using birth records to identify pregnancies and birth outcomes and hospital and laboratory testing records to identify influenza and non-influenza associated acute respiratory or febrile illness (ARFI) hospitalizations. ARFI hospitalized women were matched to non-hospitalized women (1:4) by country and season of conception. Log-binomial regression was used to estimate the relative risk (aRR) of preterm birth (PTB), small-for-gestational-age (SGA), and low birthweight (LBW) birth, adjusting for pre-existing medical conditions, maternal age, and parity. RESULTS: 950 pregnant women hospitalized with an ARFI were matched with 3,800 non-hospitalized pregnant women. Compared to non-hospitalized women, risk of PTB was greater among women hospitalized with influenza-associated ARFI (aRR: 1.57; 95% CI: 1.15-2.15) and non-influenza ARFI (aRR: 2.78; 95% CI: 2.12-3.65). Similar results were observed for LBW; there were no associations with SGA birth. CONCLUSIONS: ARFI hospitalization during pregnancy was associated with increased risk of PTB and LBW.

Tetanus, Diphtheria, and Acellular Pertussis and Influenza Vaccinations among Women With a Live Birth, Internet Panel Survey, 2017-2018.

OBJECTIVES: Pregnant women are at increased risk of complications from influenza, and infants are at increased risk of pertussis. Maternal influenza and Tdap (tetanus, diphtheria, and acellular pertussis) vaccination can reduce risk of these infections and related complications. Our objective was to estimate vaccination coverage with influenza and Tdap vaccines during pregnancy among women with a recent live birth. METHODS: An opt-in Internet panel survey was conducted from March 28 to April 10, 2018 among pregnant and recently pregnant women. Respondents with a live birth from August 1, 2017 through the date in which the participant completed the survey were included in the analysis. Receipt of influenza vaccination since July 1, 2017 and Tdap vaccination during pregnancy were assessed by sociodemographic characteristics, receipt of a health care provider (HCP) recommendation and/or offer of vaccination, and vaccination-related knowledge, attitudes, and beliefs. RESULTS: Less than a third (30.3%) of women with a live birth were unvaccinated during their pregnancy with both Tdap and influenza vaccines. Almost a third (32.8%) of the women reported being vaccinated with both vaccines. The majority (73.0%) of women reported receiving an HCP recommendation for both vaccines, and 54.2% of women were offered both vaccines by an HCP. Reasons for nonvaccination included negative attitudes toward influenza vaccine and lack of awareness about Tdap vaccination during pregnancy. CONCLUSIONS: Maternal Tdap and influenza vaccinations can prevent morbidity and mortality among infants and their mothers, yet many pregnant women are unvaccinated with either Tdap or influenza vaccines. Clinic-based education, along with interventions, such as standing orders and provider reminders, are strategies to increase maternal vaccination.

Factors associated with perceptions of influenza vaccine safety and effectiveness among adults, United States, 2017-2018.

BACKGROUND: Annual vaccination against seasonal influenza is widely recognized as the primary intervention method in preventing morbidity and mortality from influenza, but coverage among adults is suboptimal in the United States. Safety and effectiveness perceptions regarding vaccines are consistently cited as factors that influence adults' decisions to accept or reject vaccination. Therefore, we conducted this analysis in order to understand sociodemographic, attitude, and knowledge factors associated with these perceptions for influenza vaccine among adults in three different age groups. METHODS: Probability-based Internet panel surveys using nationally representative samples of adults aged ≥19 years in the United States were conducted during February-March of 2017 and 2018. We asked respondents if they believed the influenza vaccine was safe and effective. We calculated prevalence ratios using chi-square and pairwise t-tests to determine associations between safety and effectiveness beliefs and sociodemographic variables for adults aged 19-49, 50-64, and ≥65 years. RESULTS: Survey completion rates were 58.2% (2017) and 57.2% (2018); we analyzed 4597 combined responses. Overall, most adults reported the influenza vaccine was safe (86.3%) and effective (73.0%). However, fewer younger adults reported positive perceptions compared with older age groups. Respondents who believed the vaccine was safe also reported it was effective. CONCLUSIONS: Generally, adults perceived the influenza vaccine as safe and effective. Considering this, any improvements to these perceptions would likely be minor and have a limited effect on coverage. Future research to understand why, despite positive perceptions, adults are still choosing to forego the vaccine may be informative.

Epidemiology and Clinical Outcomes of Hospitalizations for Acute Respiratory or Febrile Illness and Laboratory-Confirmed Influenza Among Pregnant Women During Six Influenza Seasons, 2010-2016.

BACKGROUND: Pregnant women are at increased risk of seasonal influenza hospitalizations, but data about the epidemiology of severe influenza among pregnant women remain largely limited to pandemics. METHODS: To describe the epidemiology of hospitalizations for acute respiratory infection or febrile illness (ARFI) and influenza-associated ARFI among pregnant women, administrative and electronic health record data were analyzed from retrospective cohorts of pregnant women hospitalized with ARFI who had testing for influenza viruses by reverse-transcription polymerase chain reaction (RT-PCR) in Australia, Canada, Israel, and the United States during 2010-2016. RESULTS: Of 18 048 ARFI-coded hospitalizations, 1064 (6%) included RT-PCR testing for influenza viruses, 614 (58%) of which were influenza positive. Of 614 influenza-positive ARFI hospitalizations, 35% were in women with low socioeconomic status, 20% with underlying conditions, and 67% in their third trimesters. The median length of influenza-positive hospitalizations was 2 days (interquartile range, 1-4), 18% (95% confidence interval [CI], 15%-21%) resulted in delivery, 10% (95% CI, 8%-12%) included a pneumonia diagnosis, 5% (95% CI, 3%-6%) required intensive care, 2% (95% CI, 1%-3%) included a sepsis diagnosis, and <1% (95% CI, 0%-1%) resulted in respiratory failure. CONCLUSIONS: Our findings characterize seasonal influenza hospitalizations among pregnant women and can inform assessments of the public health and economic impact of seasonal influenza on pregnant women.

Vital Signs: Burden and Prevention of Influenza and Pertussis Among Pregnant Women and Infants - United States.

INTRODUCTION: Vaccinating pregnant women with influenza vaccine and tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine (Tdap) can reduce influenza and pertussis risk for themselves and their infants. METHODS: Surveillance data were analyzed to ascertain influenza-associated hospitalization among pregnant women and infant hospitalization and death associated with influenza and pertussis. An Internet panel survey was conducted during March 27-April 8, 2019, among women aged 18-49 years who reported being pregnant any time since August 1, 2018. Influenza vaccination before or during pregnancy was assessed among respondents with known influenza vaccination status who were pregnant any time during October 2018-January 2019 (2,097). Tdap receipt during pregnancy was assessed among respondents with known Tdap status who reported a live birth by their survey date (817). RESULTS: From 2010-11 to 2017-18, pregnant women accounted for 24%-34% of influenza-associated hospitalizations per season among females aged 15-44 years. From 2010 to 2017, a total of 3,928 pertussis-related hospitalizations were reported among infants aged <2 months (annual range = 262-743). Maternal influenza and Tdap vaccination coverage rates reported as of April 2019 were 53.7% and 54.9%, respectively. Among women whose health care providers offered vaccination or provided referrals, 65.7% received influenza vaccine and 70.5% received Tdap. The most commonly reported reasons for nonvaccination were believing the vaccine is not effective (influenza; 17.6%) and not knowing that vaccination is needed during each pregnancy (Tdap; 37.9%), followed by safety concerns for the infant (influenza =15.9%; Tdap = 17.1%). CONCLUSIONS AND IMPLICATIONS FOR PUBLIC HEALTH PRACTICE: Many pregnant women do not receive the vaccines recommended to protect themselves and their infants, even when vaccination is offered. CDC and provider organizations' resources are available to help providers convey strong, specific recommendations for influenza and Tdap vaccination that are responsive to pregnant women's concerns.

Factors associated with recruitment, surveillance participation, and retention in an observational study of pregnant women and influenza.

BACKGROUND: This report describes the results of recruitment efforts and the subsequent participation of pregnant women in study activities in a 2010-2012 observational study focused on influenza illness and vaccination in California and Oregon, USA. METHODS: Socio-demographic and health characteristics extracted from electronic medical records were compared among pregnant women who enrolled in the study, refused to participate, or were never reached for study invitation. These characteristics plus additional self-reported information were compared between women who enrolled in two study tracks: a prospective cohort vs. women enrolled following an acute respiratory illness (ARI) medical encounter. The characteristics of women who participated in weekly ARI surveillance (cohort enrollees, year one) and a 6-month follow-up interview (all enrollees) were also examined. RESULTS: In year one, we reached 51% (6938/13,655) of the potential participants we tried to contact by telephone, and 20% (1374/6938) of the women we invited agreed to join the prospective cohort. Women with chronic medical conditions, pregnancy complications, and medical encounters for ARI (prior to pregnancy or during the study period) were more likely to be reached for recruitment and more likely to enroll in the cohort. Twenty percent of cohort enrollees never started weekly surveillance reports; among those who did, reports were completed for 55% of the surveillance weeks. Receipt of the influenza vaccine was higher among women who joined the cohort (76%) than those who refused (56%) or were never reached (54%). In contrast, vaccine uptake among medical enrollees in year one (54%; 53/98) and two (52%; 79/151) was similar to other pregnant women in those years. Study site, white race, non-Hispanic ethnicity, and not having a child aged < 13 years at home were most consistently associated with joining as a cohort or medical enrollee and completing study activities after joining. CONCLUSIONS: We observed systematic differences in socio-demographic and health characteristics across different levels of participant engagement and between cohort and medical enrollees. More methodological research and innovation in conducting prospective observational studies in this population are needed, especially when extended participant engagement and ongoing surveillance are required.

Influenza Vaccine Effectiveness in Preventing Influenza-associated Hospitalizations During Pregnancy: A Multi-country Retrospective Test Negative Design Study, 2010-2016.

BACKGROUND: To date, no study has examined influenza vaccine effectiveness (IVE) against laboratory-confirmed influenza-associated hospitalizations during pregnancy. METHODS: The Pregnancy Influenza Vaccine Effectiveness Network (PREVENT) consisted of public health or healthcare systems with integrated laboratory, medical, and vaccination records in Australia, Canada (Alberta and Ontario), Israel, and the United States (California, Oregon, and Washington). Sites identified pregnant women aged 18 through 50 years whose pregnancies overlapped with local influenza seasons from 2010 through 2016. Administrative data were used to identify hospitalizations with acute respiratory or febrile illness (ARFI) and clinician-ordered real-time reverse transcription polymerase chain reaction (rRT-PCR) testing for influenza viruses. Overall IVE was estimated using the test-negative design and adjusting for site, season, season timing, and high-risk medical conditions. RESULTS: Among 19450 hospitalizations with an ARFI discharge diagnosis (across 25 site-specific study seasons), only 1030 (6%) of the pregnant women were tested for influenza viruses by rRT-PCR. Approximately half of these women had pneumonia or influenza discharge diagnoses (54%). Influenza A or B virus infections were detected in 598/1030 (58%) of the ARFI hospitalizations with influenza testing. Across sites and seasons, 13% of rRT-PCR-confirmed influenza-positive pregnant women were vaccinated compared with 22% of influenza-negative pregnant women; the adjusted overall IVE was 40% (95% confidence interval = 12%-59%) against influenza-associated hospitalization during pregnancy. CONCLUSION: Between 2010 and 2016, influenza vaccines offered moderate protection against laboratory-confirmed influenza-associated hospitalizations during pregnancy, which may further inform the benefits of maternal influenza vaccination programs.

Influenza Vaccination Coverage Among Health Care Personnel - United States, 2017-18 Influenza Season.

The Advisory Committee on Immunization Practices (ACIP) recommends that all health care personnel receive an annual influenza vaccination to reduce influenza-related morbidity and mortality among health care personnel and their patients and to reduce absenteeism among health care personnel (1-4). CDC conducted an opt-in Internet panel survey of 2,265 U.S. health care personnel to estimate influenza vaccination coverage among these persons during the 2017-18 influenza season. Overall, 78.4% of health care personnel reported receiving influenza vaccination during the 2017-18 season, similar to reported coverage in the previous four influenza seasons (5). As in previous seasons, coverage was highest among personnel who were required by their employer to be vaccinated (94.8%) and lowest among those working in settings where vaccination was not required, promoted, or offered on-site (47.6%). Health care personnel working in long-term care settings, the majority of whom work as assistants or aides, have lower influenza vaccination coverage than do health care personnel working in all other health care settings, which puts the elderly in long-term settings at increased risk for severe complications for influenza. Implementing workplace strategies shown to improve vaccination coverage among health care personnel, including vaccination requirements and active promotion of on-site vaccinations at no cost, can help ensure health care personnel and patients are protected against influenza (6). CDC's long-term care web-based toolkit* provides resources, strategies, and educational materials for increasing influenza vaccination among health care personnel in long-term care settings.

Influenza and Tdap Vaccination Coverage Among Pregnant Women - United States, April 2018.

Vaccinating pregnant women with influenza and tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccines can reduce the risk for influenza and pertussis for themselves and their infants. The Advisory Committee on Immunization Practices (ACIP) recommends that all women who are or might be pregnant during the influenza season receive influenza vaccine, which can be administered any time during pregnancy (1). The ACIP also recommends that women receive Tdap during each pregnancy, preferably from 27 through 36 weeks' gestation (2). To assess influenza and Tdap vaccination coverage among women pregnant during the 2017-18 influenza season, CDC analyzed data from an Internet panel survey conducted during March 28-April 10, 2018. Among 1,771 survey respondents pregnant during the peak influenza vaccination period (October 2017-January 2018), 49.1% reported receiving influenza vaccine before or during their pregnancy. Among 700 respondents who had a live birth, 54.4% reported receiving Tdap during their pregnancy. Women who reported receiving a provider offer of vaccination had higher vaccination coverage than did women who received a recommendation but no offer and women who did not receive a recommendation. Reasons for nonvaccination included concern about effectiveness of the influenza vaccine and lack of knowledge regarding the need for Tdap vaccination during every pregnancy. Provider offers or referrals for vaccination in combination with patient education could reduce missed opportunities for vaccination and increase vaccination coverage among pregnant women.

Influenza Vaccination Coverage Among Pregnant Women - United States, 2016-17 Influenza Season.

Pregnant women and their infants are at increased risk for severe influenza-associated illness (1), and since 2004, the Advisory Committee on Immunization Practices (ACIP) has recommended influenza vaccination for all women who are or might be pregnant during the influenza season, regardless of the trimester of the pregnancy (2). To assess influenza vaccination coverage among pregnant women during the 2016-17 influenza season, CDC analyzed data from an Internet panel survey conducted during March 28-April 7, 2017. Among 1,893 survey respondents pregnant at any time during October 2016-January 2017, 53.6% reported having received influenza vaccination before (16.2%) or during (37.4%) pregnancy, similar to coverage during the preceding four influenza seasons. Also similar to the preceding influenza season, 67.3% of women reported receiving a provider offer for influenza vaccination, 11.9% reported receiving a recommendation but no offer, and 20.7% reported receiving no recommendation; among these women, reported influenza vaccination coverage was 70.5%, 43.7%, and 14.8%, respectively. Among women who received a provider offer for vaccination, vaccination coverage differed by race/ethnicity, education, insurance type, and other sociodemographic factors. Use of evidence-based practices such as provider reminders and standing orders could reduce missed opportunities for vaccination and increase vaccination coverage among pregnant women.

Influenza Vaccination Coverage Among Pregnant Women--United States, 2014-15 Influenza Season.

Pregnant women and infants are at increased risk for influenza-related complications and hospitalization. Influenza vaccination can reduce the risk for influenza-related illness among pregnant women and their infants. Since 2004, the Advisory Committee on Immunization Practices (ACIP) and the American College of Obstetricians and Gynecologists (ACOG) have recommended influenza vaccination for all women who are or will be pregnant during the influenza season, regardless of trimester of pregnancy. To assess influenza vaccination coverage among pregnant women during the 2014­15 influenza season, CDC analyzed data from an Internet panel survey conducted during March 31­April 6, 2015. Among 1,702 survey respondents who were pregnant at any time during October 2014­January 2015, 50.3% reported receiving influenza vaccination before or during pregnancy, similar to the reported coverage in the preceding season. Overall, 64.9% of respondents reported receiving a provider offer of influenza vaccination, 14.8% received a recommendation but no offer, and 20.3% received no recommendation. Vaccination coverage among these groups of women was 67.9%, 33.5%, and 8.5%, respectively. Reminder systems and standing orders that allow health care personnel other than the attending provider to assess vaccination status and administer vaccination, can help to ensure that influenza vaccination is recommended and offered to a pregnant woman at each provider visit to increase pregnant women's vaccination coverage.