Sarah Ball

Effectiveness of Seasonal Trivalent Influenza Vaccine for Preventing Influenza Virus Illness Among Pregnant Women: A Population-Based Case-Control Study During the 2010–2011 and 2011–2012 Influenza Seasons

BACKGROUND Although vaccination with trivalent inactivated influenza vaccine (TIV) is recommended for all pregnant women, no vaccine effectiveness (VE) studies of TIV in pregnant women have assessed laboratory-confirmed influenza outcomes. METHODS We conducted a case-control study over 2 influenza seasons (2010-2011 and 2011-2012) among Kaiser Permanente health plan members in 2 metropolitan areas in California and Oregon. We compared the proportion vaccinated among 100 influenza cases (confirmed by reverse transcription polymerase chain reaction) with the proportions vaccinated among 192 controls with acute respiratory illness (ARI) who tested negative for influenza and 200 controls without ARI (matched by season, site, and trimester). RESULTS Among influenza cases, 42% were vaccinated during the study season compared to 58% and 63% vaccinated among influenza-negative controls and matched ARI-negative controls, respectively. The adjusted VE of the current season vaccine against influenza A and B was 44% (95% confidence interval [CI], 5%-67%) using the influenza-negative controls and 53% (95% CI, 24%-72%) using the ARI-negative controls. Receipt of the prior seasons vaccine, however, had an effect similar to receipt of the current seasons vaccine. As such, vaccination in either or both seasons had statistically similar adjusted VE using influenza-negative controls (VE point estimates range = 51%-76%) and ARI-negative controls (48%-76%). CONCLUSIONS Influenza vaccination reduced the risk of ARI associated with laboratory-confirmed influenza among pregnant women by about one-half, similar to VE observed among all adults during these seasons.

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

Safety of influenza vaccination during pregnancy: A review of subsequent maternal obstetric events and findings from two recent cohort studies

Pregnant women and their infants are vulnerable to severe disease and secondary complications from influenza infection. For this reason, annual influenza vaccination is recommended for all pregnant women in the United States. Women frequently cite concerns about vaccine safety as a barrier to vaccination. This review describes the safety of inactivated influenza vaccination during pregnancy with a focus on maternal obstetric events, including hypertensive disorders, gestational diabetes, and chorioamnionitis. Included in the review are new findings from two studies which examined the safety of seasonal inactivated influenza vaccination during pregnancy. The first study enrolled 641 pregnant women during the 2010-2011 season and prospectively followed them until delivery or pregnancy termination. The second study enrolled 1616 pregnant women during the 2010-2011 influenza season, and followed the women and their infants for six months after delivery. No associations between inactivated influenza vaccination and gestational diabetes, gestational hypertension, preeclampsia/eclampsia, or chorioamnionitis were observed in either cohort. When considered as a whole, these studies should further reassure women and clinicians that influenza vaccination during pregnancy is safe for mothers.

Effects of Repeated Annual Inactivated Influenza Vaccination among Healthcare Personnel on Serum Hemagglutinin Inhibition Antibody Response to A/Perth/16/2009 (H3N2)-like virus during 2010-11.

BACKGROUND Recently, lower estimates of influenza vaccine effectiveness (VE) against A(H3N2) virus illness among those vaccinated during the previous season or multiple seasons have been reported; however, it is unclear whether these effects are due to differences in immunogenicity. METHODS We performed hemagglutination inhibition antibody (HI) assays on serum collected at preseason, ∼ 30 days post-vaccination, and postseason from a prospective cohort of healthcare personnel (HCP). Eligible participants had medical and vaccination records for at least four years (since July, 2006), including 578 HCP who received 2010-11 trivalent inactivated influenza vaccine [IIV3, containing A/Perth/16/2009-like A(H3N2)] and 209 HCP who declined vaccination. Estimates of the percentage with high titers (≥ 40 and>100) and geometric mean fold change ratios (GMRs) to A/Perth/16/2009-like virus by number of prior vaccinations were adjusted for age, sex, race, education, household size, hospital care responsibilities, and study site. RESULTS Post-vaccination GMRs were inversely associated with the number of prior vaccinations, increasing from 2.3 among those with 4 prior vaccinations to 6.2 among HCP with zero prior vaccinations (F[4,567]=9.97, p<.0005). Thirty-two percent of HCP with 1 prior vaccination achieved titers >100 compared to only 11% of HCP with 4 prior vaccinations (adjusted odds ratio=6.8, 95% CI=3.1 - 15.3). CONCLUSION Our findings point to an exposure-response association between repeated IIV3 vaccination and HI for A(H3N2) and are consistent with recent VE observations. Ultimately, better vaccines and vaccine strategies may be needed in order to optimize immunogenicity and VE for HCP and other repeated vaccinees.

Comparison of Serum Hemagglutinin and Neuraminidase Inhibition Antibodies After 2010–2011 Trivalent Inactivated Influenza Vaccination in Healthcare Personnel

Background. Most inactivated influenza vaccines contain purified and standardized hemagglutinin (HA) and residual neuraminidase (NA) antigens. Vaccine-associated HA antibody responses (hemagglutination inhibition [HAI]) are well described, but less is known about the immune response to the NA. Methods. Serum of 1349 healthcare personnel (HCP) electing or declining the 2010–2011 trivalent-inactivated influenza vaccine ([IIV3], containing A/California/7/2009 p(H1N1), A/Perth/16/2009 [H3N2], B/Brisbane/60/2008 strains) were tested for NA-inhibiting (NAI) antibody by a modified lectin-based assay using pseudotyped N1 and N2 influenza A viruses with an irrelevant (H5) HA. Neuraminidase-inhibiting and HAI antibody titers were evaluated approximately 30 days after vaccination and end-of-season for those with polymerase chain reaction (PCR)-confirmed influenza infection. Results. In 916 HCP (68%) receiving IIV3, a 2-fold increase in N1 and N2 NAI antibody occurred in 63.7% and 47.3%, respectively. Smaller responses occurred in HCP age >50 years and those without prior 2009–2010 IIV3 nor monovalent A(H1N1)pdm09 influenza vaccinations. Forty-four PCR-confirmed influenza infections were observed, primarily affecting those with lower pre-exposure HAI and NAI antibodies. Higher pre-NAI titers correlated with shorter duration of illness for A(H1N1)pdm09 virus infections. Conclusions. Trivalent-inactivated influenza vaccine is modestly immunogenic for N1 and N2 antigens in HCP. Vaccines eliciting robust NA immune responses may improve efficacy and reduce influenza-associated morbidity.

Antibody Response to Influenza A(H1N1)pdm09 Among Healthcare Personnel Receiving Trivalent Inactivated Vaccine: Effect of Prior Monovalent Inactivated Vaccine

Abstract Background. Few data are available on the immunogenicity of repeated annual doses of influenza A(H1N1)pdm09-containing vaccines. Methods. We enrolled healthcare personnel (HCP) in direct patient care during the autumn of 2010 at 2 centers with voluntary immunization. We verified the receipt of A(H1N1)pdm09-containing monovalent inactivated influenza vaccine (MIIV) and 2010–2011 trivalent inactivated vaccine (TIV). We performed hemagglutination inhibition antibody (HI) assays on preseason, post-TIV, and end-of-season serum samples. We compared the proportion of HCPs with HI titer ≥40 against A(H1N1)pdm09 per receipt of prior-season MIIV, current-season TIV, both, or neither. Results. At preseason (n = 1417), HI ≥ 40 was significantly higher among those who received MIIV (34%) vs those who did not (14%) (adjusted relative risk [ARR], 3.26; 95% confidence interval [CI], 2.72–3.81). At post-TIV (n = 865), HI ≥ 40 was lower among HCP who received MIIV and TIV (66%) than among those receiving only TIV (85%) (ARR, 0.93 [95% CI, .84–.997]). At end-of-season (n = 1254), HI ≥ 40 was 40% among those who received both MIIV and TIV and 67% among those receiving only TIV (ARR, 0.76 [95% CI, .65–.88]), 52% among those who received MIIV only, and 12% among those receiving neither. Conclusions. HCP immunization programs should consider effects of host immune response and vaccine antigenic distance on immunogenicity of repeated annual doses of influenza vaccines.

Changes in self-rated health and subjective social status over time in a cohort of healthcare personnel

As part of a prospective cohort study of 1354 female and 347 male healthcare personnel, we examined the stability of subjective social status over ~7 months and the prospective association between subjective social status and self-rated health status. Most (82%) subjective social status ratings were stable (within ±1 point). Lower baseline subjective social status among healthcare personnel was associated with more subsequent reports of fatigue and headache and worsening global self-rated health status. Healthcare personnel who placed themselves on the bottom half of the subjective social status ladder were four times more likely to experience a decline in global self-rated health status and half as likely to improve to excellent self-rated health status.

Comparison of Laboratory-Confirmed Influenza and Noninfluenza Acute Respiratory Illness in Healthcare Personnel during the 2010-2011 Influenza Season

OBJECTIVE Compare the severity of illnesses associated with influenza and noninfluenza acute respiratory illness (ARI) in healthcare personnel (HCP). DESIGN Prospective observational cohort. PARTICIPANTS HCP at 2 healthcare organizations with direct patient contact were enrolled prior to the 2010-2011 influenza season. METHODS HCP who were fewer than 8 days from the start of fever/feverishness/chills and cough were eligible for real-time reverse-transcription polymerase chain reaction influenza virus testing of respiratory specimen. Illness severity was assessed by the sum of self-rated severity (0, absent; 3, severe) of 12 illness symptoms, subjective health (0, best health; 9, worst health), activities of daily living impairment (0, able to perform; 9, unable to perform), missed work, and duration of illness. RESULTS Of 1,701 HCP enrolled, 267 were tested for influenza, and 58 (22%) of these tested positive. Influenza compared with noninfluenza illnesses was associated with higher summed 12-symptom severity score (mean [standard deviation], 17.9 [5.4] vs 14.6 [4.8]; P < .001), worse subjective health (4.5 [1.8] vs 4.0 [1.8]; P <.05), greater impairment of activities of daily living (4.9 [2.5] vs 3.8 [2.5]; P < .01), and more missed work (12.1 [10.5] vs 7.8 [10.5] hours; P < .01). Differences in symptom severity, activities of daily living, and missed work remained significant after adjusting for illness and participant characteristics. CONCLUSIONS Influenza had a greater negative impact on HCP than noninfluenza ARIs, indicated by higher symptom severity scores, less ability to perform activities of daily living, and more missed work. These results highlight the importance of efforts to prevent influenza infection in HCP.

Consistency of Influenza A Virus Detection Test Results across Respiratory Specimen Collection Methods Using Real-Time Reverse Transcription-PCR

ABSTRACT In our prospective cohort study, we compared the performance of nasopharyngeal, oropharyngeal, and nasal swabs for the detection of influenza virus using real-time reverse transcription-PCR assay. Joint consideration of results from oropharyngeal and nasal swabs was as effective as consideration of results from nasopharyngeal swabs alone, as measured by sensitivity and noninferiority analysis.

The Association Between Influenza Vaccination and Other Preventative Health Behaviors in a Cohort of Pregnant Women

Objectives. Although pregnant women are a high-priority group for seasonal influenza vaccination, vaccination rates in this population remain below target levels. Previous studies have identified sociodemographic predictors of vaccine choice, but relationships between preconception heath behaviors and seasonal influenza vaccination are poorly understood. This prospective cohort study followed pregnant women during the 2010-2011 influenza season to determine if certain health behaviors were associated with vaccination status. Method. Participants were pregnant women receiving prenatal care from Kaiser Permanente Northwest and Kaiser Permanente Northern California. Women were surveyed about preconception smoking, alcohol consumption, and vitamin/supplement use. Vaccination data were obtained from health plan databases and state immunization records. Results. Data from 1,204 women were included in this analysis. Most participants (1,204; 66.4%) received a seasonal influenza vaccine during the study period. Women vaccinated prior to pregnancy were more likely to use a supplement containing folic acid (80%) or vitamin D (30%) compared with women who were vaccinated during pregnancy (72% and 15%, respectively) or unvaccinated women (62% and 12%, respectively, p < .001). Women vaccinated prior to or during pregnancy were more likely (75%) to have never smoked compared with women who were not vaccinated (70%, p = .005). There were no significant differences in alcohol use or household cigarette smoke exposure by vaccination group. Conclusions. Women who engaged in specific preconception health behaviors were more likely to receive seasonal influenza vaccination. Failure to participate in these health behaviors could alert health care practitioners to patients’ increased risk of remaining unvaccinated during pregnancy.