Differences and disparities in seasonal influenza vaccine, acceptance, adverse reactions, and coverage by age, sex, gender, and race

Evaluating equity-promoting interventions to prevent race-based inequities in influenza outcomes

Importance

Seasonal influenza hospitalizations pose a considerable burden in the United States, with BIPOC (Black, Indigenous, and other People of Color) communities being disproportionately affected.

Objective

To determine and quantify the effects of different types of mitigation strategies on inequities in influenza outcomes (symptomatic infections and hospitalizations).

Design

In this simulation study, we fit a race-stratified agent-based model of influenza transmission to demographic and hospitalization data of the United States.

Participants

We consider five racial-ethnic groups: non-Hispanic White persons, non- Hispanic Black persons, non-Hispanic Asian persons, non-Hispanic American Indian or Alaska Native persons, and Hispanic or Latino persons.

Setting

We tested five idealized equity-promoting interventions to determine their effectiveness in reducing inequity in influenza outcomes. The interventions assumed (i) equalized vaccination rates, (ii) equalized comorbidities, (iii) work-risk distribution proportional to the distribution of the population, (iv) reduced work contacts for all, or (v) a combination of equalizing vaccination rates and comorbidities and reducing work contacts.

Main Outcomes and Measures

Reduction in symptomatic or hospitalization risk ratios, defined as the ratio of the number of symptomatic infections (hospitalizations respectively) in each age- and racial-ethnic group and their corresponding white counterpart. We also evaluated the reduction in the absolute mean number of symptomatic infections or hospitalizations in each age- and racial-ethnic group compared to the fitted scenario (baseline).

Results

Our analysis suggests that symptomatic infections were equalized and reduced (by up to 17% in BIPOC adults aged 18-49) by strategies reducing work contacts or equalizing vaccination rates. Reducing comorbidities resulted in significant decreases in hospitalizations, with a reduction of over 40% in BIPOC groups. All tested interventions reduced the inequity in influenza hospitalizations in all racial-ethnic groups, but interventions reducing comorbidities in marginalized populations were the most effective. Notably, these interventions resulted in better outcomes across all racial-ethnic groups, not only those prioritized by the interventions.

Conclusions and Relevance

In this simulation modeling study, equalizing vaccination rates and reducing number of work contacts (which are relatively simple strategies to implement) reduced the both the inequity in hospitalizations and the absolute number of symptomatic infections and hospitalizations in all age and racial-ethnic groups.

Sex and gender differences in adverse events following influenza and COVID-19 vaccination

INTRODUCTION

Active and passive surveillance studies have found that a greater proportion of females report adverse events (AE) following receipt of either the COVID-19 or seasonal influenza vaccine compared to males. In a predominately young adult female population of healthcare workers, we sought to determine the intersection of biological sex and sociocultural gender differences in prospective active reporting of vaccine outcomes, which remains poorly characterized.

METHODS

This cohort study enrolled Johns Hopkins Health System healthcare workers (HCWs) who were recruited from the mandatory annual fall 2019-2022 influenza vaccine and the fall 2022 COVID-19 bivalent vaccine campaigns. Vaccine recipients were enrolled the day of vaccination and AE surveys were administered two days post-vaccination for bivalent COVID-19 and influenza vaccine recipients. Data were collected regarding the presence of a series of solicited local and systemic AEs. Open-ended answers about participants' experiences with AEs also were collected for the COVID-19 vaccine recipients.

RESULTS

Females were more likely to report local AEs after either influenza (OR = 2.28, p = 0.001) or COVID-19 (OR = 2.57, p = 0.008) vaccination compared to males, regardless of age or race. Males and females had comparable probabilities of reporting systemic AEs after either influenza (OR = 1.18, p = 0.552) or COVID-19 (OR = 0.96, p = 0.907) vaccination. Hormonal birth control use did not impact the rates of reported AEs following influenza vaccination among reproductive-aged female HCWs. Women reported more interruptions in their daily routine following COVID-19 vaccination than men and were more likely to seek out self-treatment. More women than men scheduled their COVID-19 vaccination before their days off in anticipation of AEs.

CONCLUSIONS

Our findings highlight the need for sex- and gender-inclusive policies to inform more effective mandatory occupational health vaccination strategies. Further research is needed to evaluate the potential disruption of AEs on occupational responsibilities following mandated vaccination for healthcare workers, a predominately female population, and to more fully characterize the post-vaccination behavioral differences between men and women.

Determinants of influenza non-vaccination among Canadian children: insights from a nationwide survey

Background

To identify determinants influencing Canadian parents' decision not to vaccinate their children aged 6 months to 17 years against seasonal influenza.

Methods

Data from the 2022 Childhood COVID-19 Immunization Coverage Survey, a national survey of approximately 10,500 Canadian parents/guardians and their children, was analyzed. The survey examined influenza vaccine coverage, parental perspectives on vaccines, reasons for hesitancy, and factors influencing immunization. Socio-demographic characteristics, including ethnicity, household income, working sector, educational attainment, and prevalence of chronic medical conditions among children were considered. Historical vaccine uptake and the impact of the COVID-19 pandemic on immunization decisions were also reviewed. Key determinants of non-vaccination in the 2021-2022 influenza season were analyzed using multivariable logistic regression, with a statistical significance level set at p-value <0·05.

Results

70% of children aged 6 months to 17 years did not receive the seasonal influenza vaccine. Key predictors for non-vaccination included: residing in rural settings (aOR 1·35, 95% CI 1·13-1·60), parental education attainment of less than high school (aOR 2·48, 95% CI 1·24-4·97), and the absence of chronic medical conditions in children (aOR 1.60, 95% CI 1.34-1.91)· Other strong predictors included lower household income; deterrence due to the COVID-19 pandemic; and parental hesitancy stemming from concerns about the vaccine's safety, effectiveness, and by beliefs that their child was not at risk of contracting the influenza or severe consequences from the infection.

Conclusion

This research underscores pivotal determinants of parental decisions not to vaccinate their children against seasonal influenza and sheds light on the impact of the COVID-19 pandemic. The results highlight the importance of addressing safety concerns and providing clear information to alleviate hesitancy.

Identifying and overcoming COVID-19 vaccination impediments using Bayesian data mining techniques

The COVID-19 pandemic has profoundly reshaped human life. The development of COVID-19 vaccines has offered a semblance of normalcy. However, obstacles to vaccination have led to substantial loss of life and economic burdens. In this study, we analyze data from a prominent health insurance provider in the United States to uncover the underlying reasons behind the inability, refusal, or hesitancy to receive vaccinations. Our research proposes a methodology for pinpointing affected population groups and suggests strategies to mitigate vaccination barriers and hesitations. Furthermore, we estimate potential cost savings resulting from the implementation of these strategies. To achieve our objectives, we employed Bayesian data mining methods to streamline data dimensions and identify significant variables (features) influencing vaccination decisions. Comparative analysis reveals that the Bayesian method outperforms cutting-edge alternatives, demonstrating superior performance.

Prediction and detection of side effects severity following COVID-19 and influenza vaccinations: utilizing smartwatches and smartphones

Vaccines stand out as one of the most effective tools in our arsenal for reducing morbidity and mortality. Nonetheless, public hesitancy towards vaccination often stems from concerns about potential side effects, which can vary from person to person. As of now, there are no automated systems available to proactively warn against potential side effects or gauge their severity following vaccination. We have developed machine learning (ML) models designed to predict and detect the severity of post-vaccination side effects. Our study involved 2111 participants who had received at least one dose of either a COVID-19 or influenza vaccine. Each participant was equipped with a Garmin Vivosmart 4 smartwatch and was required to complete a daily self-reported questionnaire regarding local and systemic reactions through a dedicated mobile application. Our XGBoost models yielded an area under the receiver operating characteristic curve (AUROC) of 0.69 and 0.74 in predicting and detecting moderate to severe side effects, respectively. These predictions were primarily based on variables such as vaccine type (influenza vs. COVID-19), the individual's history of side effects from previous vaccines, and specific data collected from the smartwatches prior to vaccine administration, including resting heart rate, heart rate, and heart rate variability. In conclusion, our findings suggest that wearable devices can provide an objective and continuous method for predicting and monitoring moderate to severe vaccine side effects. This technology has the potential to improve clinical trials by automating the classification of vaccine severity.

Race and gender disparities in preventive health activity engagement of older adults in the southeastern United States

A cross-sectional study was conducted to determine preventive-health-activity engagement in community-dwelling older adults participating in student-led health screenings in east Alabama. From 2017-2019, health professions students conducted health screenings at 23 community and independent living sites to assess medical and social needs of adults. Clients' responses to questions regarding vaccinations (flu/pneumonia/shingles), cancer screenings (colon/sex-specific), and other (dental/vision) screenings were aggregated to create a preventive health behavior (prevmed) score. Chi-square, t-tests, and regression analyses were conducted. Data from 464 adults ages 50-99 (72.9±10.1) years old were analyzed. The sample was 71.3% female, 63.1% Black/African American (BA), and 33.4% rural. Linear regression indicated BA race (p=0.001), currently unmarried (p=0.030), no primary care provider (p<0.001) or insurance (p=0.010), age <65 years (p=0.042) and assessment at a residential site (p=0.037) predicted lower prevmed scores. Social factors predict preventive health activity engagement in community-dwelling adults in east Alabama, indicating several opportunities to improve health outcomes.

Polyphenol rich sugarcane extract (PRSE) has potential antiviral activity against influenza A virus in vitro

Influenza A virus (IAV) is one of the major global public health concerns but the emerging resistance of IAV to currently available antivirals requires the need to identify potential alternatives. Polyphenol rich sugarcane extract (PRSE) is an extract prepared from the sugarcane plant Saccharum Officinarum. Herein we aimed to determine if PRSE had antiviral activity against IAV. We showed that treatment of IAV-infected cells with PRSE results in a dose-dependent inhibition of virus infection at concentrations that were non-cytotoxic. PRSE treatment limited the early stages of infection, reducing viral genome replication, mRNA transcription and viral protein expression. PRSE did not affect the ability of IAV to bind sialic acid or change the morphology of viral particles. Additionally, PRSE treatment attenuated the replication of multiple IAV strains of the H3N2 and H1N1 subtype. In conclusion, we show that PRSE displays antiviral activity against a broad range of IAV strains, in vitro.

Sex and gender differences in adverse events following receipt of influenza and COVID-19 vaccination among healthcare workers

Introduction

Active and passive surveillance studies have found that a greater proportion of females report adverse events (AE) following receipt of either the COVID-19 or seasonal influenza vaccine compared to males. We sought to determine the intersection of biological sex and sociocultural gender differences in prospective active reporting of vaccine outcomes, which remains poorly characterized.

Methods

This cohort study enrolled Johns Hopkins Health System healthcare workers (HCWs) who were recruited from the annual fall 2019-2022 influenza vaccine and the fall 2022 COVID-19 bivalent vaccine campaigns. Vaccine recipients were enrolled the day of vaccination and AE surveys were administered two days post-vaccination (DPV) for bivalent COVID-19 and Influenza vaccine recipients. Data were collected regarding the presence of a series of solicited local and systemic AEs. Open-ended answers about participants' experiences with AEs also were collected for the COVID-19 vaccine recipients.

Results

Females were more likely to report local AEs after influenza (OR=2.28, p=0.001) or COVID-19 (OR=2.57, p=0.008) vaccination compared to males, regardless of age or race. Males and females had comparable probabilities of reporting systemic AEs after influenza (OR=1.18, p=0.552) or COVID-19 (OR=0.96, p=0.907) vaccination. Exogenous hormones from birth control use did not impact the rates of reported AEs following COVID-19 vaccination among reproductive-aged female HCWs. Women reported more interruptions in their daily routine following COVID-19 vaccination than men and were more likely to seek out self-treatment. More women than men scheduled their COVID-19 vaccination before their days off in anticipation of AEs.

Conclusions

Our findings highlight the need for sex- and gender-inclusive policies to inform more effective occupational health vaccination strategies. Further research is needed to evaluate the potential disruption of AEs on occupational responsibilities following mandated vaccination for healthcare workers and to more fully characterize the post-vaccination behavioral differences between men and women.

KEY MESSAGE

What is already known on this topic: ⇒ Among diversely aged adults 18-64 years, females report more AEs to vaccines, including the influenza and COVID-19 vaccines, than males.⇒ Vaccine AEs play a role in shaping vaccine hesitancy and uptake.⇒ Vaccine uptake related to influenza and COVID-19 are higher among men than women.⇒ Research that addresses both the sex and gender disparities of vaccine outcomes and behaviors is lacking.What this study adds: ⇒ This prospective active reporting study uses both quantitative and qualitative survey data to examine sex and gender differences in AEs following influenza or COVID-19 vaccination among a cohort of reproductive-aged healthcare workers.How this study might affect research, practice, or policy: ⇒ Sex and gender differences in AEs and perceptions relating to vaccination should drive the development of more equitable and effective vaccine strategies and policies in occupational health settings.

Exploring missed opportunities for influenza vaccination and influenza vaccine co-administration patterns among Italian older adults: a retrospective cohort study

BACKGROUND

Missed opportunities constitute a main driver of suboptimal seasonal influenza vaccination (SIV) coverage in older adults. Vaccine co-administration is a way to reduce these missed opportunities. In this study, we quantified missed opportunities for SIV, identified some of their socio-structural correlates and documented SIV co-administration patterns.

METHODS

In this registry-based retrospective cohort study, we verified the SIV status of all subjects aged ≥65 years who received at least one dose of coronavirus disease 2019 (COVID-19), pneumococcal or herpes zoster vaccines during the 2022/23 influenza season. The frequency of concomitant same-day administration of SIV with other target vaccines was also assessed.

RESULTS

Among 41 112, 5482 and 3432 older adults who received ≥1 dose of COVID-19, pneumococcal and herpes zoster vaccines, missed opportunities for SIV accounted for 23.3%, 5.0% and 13.2%, respectively. Younger, male and foreign-born individuals were generally more prone to missing SIV. The co-administration of SIV with other recommended vaccines was relatively low, being 11.0%, 53.1% and 17.1% in COVID-19, pneumococcal and herpes zoster cohorts, respectively.

CONCLUSIONS

A sizeable proportion of older adults who received other recommended vaccines during the last influenza season did not receive SIV. This share of missed opportunities, which are subject to some social inequalities, may be addressed by increasing vaccine co-administration rates and implementing tailored health promotion interventions.

The Effect of Sex on the Incidence, Latency, Duration and Perceived Burden of Adverse Events Following Seasonal Influenza Vaccination in the Netherlands

INTRODUCTION

The annual reformulation of the seasonal influenza vaccine results in fluctuating frequencies and severity of adverse effects following immunization (AEFIs), which stresses the importance of pharmacovigilance. Also, sex-related factors are known to influence the development of AEFIs. This study aims to describe the difference in incidence and course (i.e., time-to-onset, time-to-recovery, and perceived burden) of AEFIs between males and females after seasonal influenza vaccination.

METHODS

We assessed data from cohort event monitoring studies, which were performed over nine consecutive years (2013-2021), each covering several months during the seasonal influenza campaign in the Netherlands. Participants reported information about AEFIs over a 30-day period in three questionnaires. The effect of sex, age, body mass index, study year, and comorbidities on the incidence of any AEFI, local reactions, fever and the five most reported AEFIs was analyzed using logistic regression. The difference in time-to-onset, time-to-recovery, and perceived burden between males and females was analyzed by the Kruskal-Wallis test.

RESULTS

The cohort included 7789 participants (53.0% females). Females had around 2.5-fold (p < 0.001) higher odds of developing any AEFI compared with males. Some study years and comorbidities were positively associated with AEFI incidence, whereas age was negatively associated. An AEFI had a significant shorter time-to-onset, a longer time-to-recovery, and a higher perceived burden in females compared to males.

CONCLUSION

Overall, the results confirm that females experience AEFIs more often than males. Additionally, this study shows that the course of AEFIs only partially differs between the sexes.

Influenza vaccination coverage among persons ages six months and older in the Vaccine Safety Datalink in the 2017-18 through 2022-23 influenza seasons

BACKGROUND

In the United States, annual vaccination against seasonal influenza is recommended for all people ages ≥ 6 months. Vaccination coverage assessments can identify populations less protected from influenza morbidity and mortality and help to tailor vaccination efforts. Within the Vaccine Safety Datalink population ages ≥ 6 months, we report influenza vaccination coverage for the 2017-18 through 2022-23 seasons.

METHODS

Across eight health systems, we identified influenza vaccines administered from August 1 through March 31 for each season using electronic health records linked to immunization registries. Crude vaccination coverage was described for each season, overall and by self-reported sex; age group; self-reported race and ethnicity; and number of separate categories of diagnoses associated with increased risk of severe illness and complications from influenza (hereafter referred to as high-risk conditions). High-risk conditions were assessed using ICD-10-CM diagnosis codes assigned in the year preceding each influenza season.

RESULTS

Among individual cohorts of more than 12 million individuals each season, overall influenza vaccination coverage increased from 41.9 % in the 2017-18 season to a peak of 46.2 % in 2019-20, prior to declaration of the COVID-19 pandemic. Coverage declined over the next three seasons, coincident with widespread SARS-CoV-2 circulation, to a low of 40.3 % in the 2022-23 season. In each of the six seasons, coverage was lowest among males, 18-49-year-olds, non-Hispanic Black people, and those with no high-risk conditions. While decreases in coverage were present in all age groups, the declines were most substantial among children: 2022-23 season coverage for children ages six months through 8 years and 9-17 years was 24.5 % and 22.4 % (14 and 10 absolute percentage points), respectively, less than peak coverage achieved in the 2019-20 season.

CONCLUSIONS

Crude influenza vaccination coverage increased from 2017 to 18 through 2019-20, then decreased to the lowest level in the 2022-23 season. In this insured population, we identified persistent disparities in influenza vaccination coverage by sex, age, and race and ethnicity. The overall low coverage, disparities in coverage, and recent decreases in coverage are significant public health concerns.

Trends in Influenza Vaccination Rates among a Medicaid Population from 2016 to 2021

Seasonal influenza is a leading cause of death in the U.S., causing significant morbidity, mortality, and economic burden. Despite the proven efficacy of vaccinations, rates remain notably low, especially among Medicaid enrollees. Leveraging Medicaid claims data, this study characterizes influenza vaccination rates among Medicaid enrollees and aims to elucidate factors influencing vaccine uptake, providing insights that might also be applicable to other vaccine-preventable diseases, including COVID-19. This study used Medicaid claims data from nine U.S. states (2016-2021], encompassing three types of claims: fee-for-service, major Medicaid managed care plan, and combined. We included Medicaid enrollees who had an in-person healthcare encounter during an influenza season in this period, excluding those under 6 months of age, over 65 years, or having telehealth-only encounters. Vaccination was the primary outcome, with secondary outcomes involving in-person healthcare encounters. Chi-square tests, multivariable logistic regression, and Fisher's exact test were utilized for statistical analysis. A total of 20,868,910 enrollees with at least one healthcare encounter in at least one influenza season were included in the study population between 2016 and 2021. Overall, 15% (N = 3,050,471) of enrollees received an influenza vaccine between 2016 and 2021. During peri-COVID periods, there was an increase in vaccination rates among enrollees compared to pre-COVID periods, from 14% to 16%. Children had the highest influenza vaccination rates among all age groups at 29%, whereas only 17% were of 5-17 years, and 10% were of the 18-64 years were vaccinated. We observed differences in the likelihood of receiving the influenza vaccine among enrollees based on their health conditions and medical encounters. In a study of Medicaid enrollees across nine states, 15% received an influenza vaccine from July 2016 to June 2021. Vaccination rates rose annually, peaking during peri-COVID seasons. The highest uptake was among children (6 months-4 years), and the lowest was in adults (18-64 years). Female gender, urban residency, and Medicaid-managed care affiliation positively influenced uptake. However, mental health and substance abuse disorders decreased the likelihood. This study, reliant on Medicaid claims data, underscores the need for outreach services.

Vaccine attitudes and acceptance among older adults in North Dakota: Understanding demographic characteristic variability

OBJECTIVES

Older adults face increased risks from infectious diseases which are often preventable with vaccines. The current study examines demographic variation in vaccine hesitancy among older adults in North Dakota.

METHODS

A mailed survey assessing age, gender, years of education, self-rated health, rurality, and political leaning as well as vaccine attitudes and vaccine acceptance was conducted with 739 older adults (65+), oversampled from rural counties.

RESULTS

Vaccine hesitant attitudes were significantly higher among rural and politically-conservative older adults; whereas, vaccine acceptance was significantly higher among older, healthier, and politically-liberal older adults. Vaccine attitudes were significantly associated with vaccine acceptance and mediated the association between political leaning and vaccine acceptance.

DISCUSSION

These findings highlight the demographic characteristics predictive of older adults' vaccine attitudes and acceptance. By better understanding the nuanced factors leading to hesitation to be vaccinated, practitioners can develop strategies to increase vaccination rates among this at-risk population.

Has the COVID-19 Pandemic Changed Parental Attitudes and Beliefs Regarding Vaccinating Their Children against the Flu?

BACKGROUND

This study assessed whether the COVID-19 pandemic has altered parents' attitudes toward vaccinating their children against the flu and barriers to school-based vaccination programs.

METHODS

A cross-sectional online survey was conducted with 975 parents of children aged 6 months to 11 years between 21-31 December 2022. A multivariate regression was performed to determine predictors of parents' willingness to vaccinate their children against the flu in the winter of 2023.

RESULTS

45% of parents did not plan to vaccinate their children against the flu, citing concerns about side effects and vaccine effectiveness; 39% already vaccinated their children, and 41% of them reported an increased intention to vaccinate following the pandemic. Only 37% of parents chose school-based vaccination programs, mainly due to a preference for HMO clinics and a lack of available nurses at school. The Health Belief Model variables, namely, perceived susceptibility, severity, and benefits, displayed the largest effect sizes.

CONCLUSIONS

Healthcare providers and public health officials should address parents' concerns about flu vaccine safety and efficacy to improve vaccination rates among children. Notably, the pandemic has increased vaccine receptivity among some parents. Enhancing accessibility to nursing staff in student health facilities could help boost vaccine uptake.

Using the theory of planned behavior to assess willingness and attitudes towards COVID-19 vaccination among a predominantly white U.S. college sample

Objective

Through the lens of behavioral models such as the Theory of Planned Behavior (TPB) and the Health Belief Model, the present study (1) investigated U.S. university students' willingness to receive the COVID-19 vaccine and (2) examined predictors (e.g. demographics, past vaccine experience, TPB constructs) of vaccine willingness.

Method

University students (n = 170) completed a survey assessing demographics, health behaviors, attitudes, perceived severity/susceptibility, norms, and vaccine intentions related to the COVID-19 pandemic. Data were collected from April 2020 through July 2020.

Results

Overall, 56.5% of participants indicated that they would be willing to receive the COVID-19 vaccine once it is available, 39.4% were unsure of whether they would receive the vaccine, and 4.1% indicated they would not receive the vaccine. Multinomial logistic regression indicated that greater adherence to CDC guidelines (p = .030) and greater perceived pro-vaccine norms (p < .001) predicted greater vaccine willingness.

Conclusions

Results from this study are consistent with previous literature on vaccine hesitancy, whereby normative beliefs and adherence to CDC guidelines were found to be determinants of vaccine willingness. To reduce transmission of the COVID-19 pandemic, interventions aimed at promoting positive attitudes towards vaccination should aim to incorporate these observed determinants.

Knowledge and identity antecedents of COVID-19 vaccine status: a study of South Carolina residents

Introduction

Despite over three years of learning about SARS-CoV-2 and extensive work to develop vaccines, vaccination rates remain suboptimal, thereby preventing our society from reaching herd immunity.

Purpose

Extant literature on vaccine hesitancy led us to hypothesize that specific socio/political variables may be contributing to low vaccination rates, particularly in South Carolina.

Methods

By use of Qualtrics surveys, we collected data from people across all counties in South Carolina regarding vaccine status, plans to vaccinate, and a host of demographics.

Results

Findings revealed that those less likely to be vaccinated against COVID-19 tended to be younger, female, republican. Interestingly, COVID-19 knowledge did not appear to differ between vaccination status groups, although COVID-19 vaccine and general vaccine knowledge did differ.

Conclusions

Our results suggest that while understanding of COVID-19 was relatively similar across groups, targeted and tailored interventions aimed at enhancing the public's general and COVID-19-specific vaccine knowledge may aid efforts to reach herd immunity.

Relationships Between Social Vulnerability and Coronavirus Disease 2019 Vaccination Coverage and Vaccine Effectiveness

BACKGROUND

Coronavirus disease 2019 (COVID-19) vaccination coverage remains lower in communities with higher social vulnerability. Factors such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) exposure risk and access to healthcare are often correlated with social vulnerability and may therefore contribute to a relationship between vulnerability and observed vaccine effectiveness (VE). Understanding whether these factors impact VE could contribute to our understanding of real-world VE.

METHODS

We used electronic health record data from 7 health systems to assess vaccination coverage among patients with medically attended COVID-19-like illness. We then used a test-negative design to assess VE for 2- and 3-dose messenger RNA (mRNA) adult (≥18 years) vaccine recipients across Social Vulnerability Index (SVI) quartiles. SVI rankings were determined by geocoding patient addresses to census tracts; rankings were grouped into quartiles for analysis.

RESULTS

In July 2021, primary series vaccination coverage was higher in the least vulnerable quartile than in the most vulnerable quartile (56% vs 36%, respectively). In February 2022, booster dose coverage among persons who had completed a primary series was higher in the least vulnerable quartile than in the most vulnerable quartile (43% vs 30%). VE among 2-dose and 3-dose recipients during the Delta and Omicron BA.1 periods of predominance was similar across SVI quartiles.

CONCLUSIONS

COVID-19 vaccination coverage varied substantially by SVI. Differences in VE estimates by SVI were minimal across groups after adjusting for baseline patient factors. However, lower vaccination coverage among more socially vulnerable groups means that the burden of illness is still disproportionately borne by the most socially vulnerable populations.

Racial and sociodemographic predictors of COVID-19 compared with influenza, appendicitis, and all-cause hospitalization: retrospective cohort analysis

OBJECTIVE

To determine whether inequities in COVID-19 infection and hospitalization differ from those for common medical conditions: influenza, appendicitis, and all-cause hospitalization.

DESIGN

Retrospective study based on electronic health records of three healthcare systems in San Francisco (university, public, and community) examining (1) racial/ethnic distribution in cases and hospitalization among patients with diagnosed COVID-19 (March-August 2020) and patients with diagnosed influenza, diagnosed appendicitis, or all-cause hospitalization (August 2017-March 2020), and (2) sociodemographic predictors of hospitalization among those with diagnosed COVID-19 and influenza.

RESULTS

Patients 18 years or older with diagnosed COVID-19 (N = 3934), diagnosed influenza (N = 5932), diagnosed appendicitis (N = 1235), or all-cause hospitalization (N = 62,707) were included in the study. The age-adjusted racial/ethnic distribution of patients with diagnosed COVID-19 differed from that of patients with diagnosed influenza or appendicitis for all healthcare systems, as did hospitalization from these conditions compared to any cause. For example, in the public healthcare system, 68% of patients with diagnosed COVID-19 were Latine, compared with 43% of patients with diagnosed influenza, and 48% of patients with diagnosed appendicitis (p < 0.05). In multivariable logistic regressions, COVID-19 hospitalizations were associated with male sex, Asian and Pacific Islander race/ethnicity, Spanish language, and public insurance in the university healthcare system, and Latine race/ethnicity and obesity in the community healthcare system. Influenza hospitalizations were associated with Asian and Pacific Islander and other race/ethnicity in the university healthcare system, obesity in the community healthcare system, and Chinese language and public insurance in both the university and community healthcare systems.

CONCLUSIONS

Racial/ethnic and sociodemographic inequities in diagnosed COVID-19 and hospitalization differed from those for diagnosed influenza and other medical conditions, with consistently higher odds among Latine and Spanish-speaking patients. This work highlights the need for disease-specific public health efforts in at-risk communities in addition to structural upstream interventions.

Association between attitudes toward the COVID-19 vaccines and mental health among 140,259 college students in China

Background

With the launch of the COVID-19 vaccines, the vaccination rate has become a hot issue of concern. However, the evidence for the relationship between college students' attitudes toward vaccines and anxiety and depressive symptoms has been limited.

Methods

In total, 140,259 college students were recruited using a cluster sampling method in Zhengzhou, Xinxiang, Xinyang city of Henan Province, China, May 21-27, 2021. Anxiety symptoms were determined by the Generalized Anxiety Disorder tool (GAD-7) and depressive symptoms were determined by the Patient Health Questionnaire (PHQ-9). Multiple logistic regression was performed to estimate the association between students' attitudes toward the vaccines and anxiety and depressive symptoms.

Results

The results indicate that 22.45% of students are unclear whether the vaccine can protect them from infection and 45.57% are unclear whether the vaccine is safe and has no side effects. In addition, after adjusting, the model showed that students who think vaccines can protect them and are safe had 0.128 (95%CI 0.110-0.150; Ptrend < 0.001) times lower risk of anxiety compared to their counterparts who think vaccines can neither protect them nor are safe. Similar ORs were found in depression (aOR = 0.157; 95%CI 0.137-0.180).

Conclusion

This large-scale study has shown an association between symptoms of anxiety and depression and reluctance to obtain vaccination.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10389-023-01830-7.

Disparities in vaccination rates in solid organ transplant patients

INTRODUCTION

Vaccinations against preventable respiratory infections such as Streptococcus pneumoniae and influenza are important in immunosuppressed solid organ transplant (SOT) recipients. Little is known about the role of age, race, ethnicity, sex, and sociodemographic factors including rurality, or socioeconomic status (SES) associated with vaccine uptake in this population.

METHODS

We conducted a population-based study using the Rochester Epidemiology Project, a medical records linkage system, to assess socioeconomic and demographic factors associated with influenza and pneumococcal vaccination rates among adult recipients of solid organ transplantation (aged 19-64 years) living in four counties in southeastern Minnesota. Vaccination data were obtained from the Minnesota Immunization Information Connection from June 1, 2010 to June 30, 2020. Vaccination rate was assessed with Poisson and logistic regression models.

RESULTS

A total of 468 SOT recipients were identified with an overall vaccination rate of 57%-63% for influenza and 56% for pneumococcal vaccines. As expected, vaccination for pneumococcal vaccine positively correlated with influenza vaccination. Rural patients had decreased vaccination in both compared to urban patients, even after adjusting for age, sex, race, ethnicity, and SES. Although the population was mostly White and non-Hispanic, neither vaccination differed by race or ethnicity, but influenza vaccination did by SES. Among organ transplant groups, liver and lung recipients were least vaccinated for influenza, and heart recipients were least up-to-date on pneumococcal vaccines.

CONCLUSIONS

Rates of vaccination were below national goals. Rurality was associated with undervaccination. Further investigation is needed to understand and address barriers to vaccination among transplant recipients.

Acceptance of COVID-19 vaccine among sub-Saharan Africans (SSA): a comparative study of residents and diasporan dwellers

BACKGROUND

The COVID-19 vaccines are being rolled out across all the sub-Saharan Africa (SSA) countries, with countries setting targets for achieving full vaccination rates. The aim of this study was to compare the uptake of, resistance and hesitancy to the COVID-19 vaccine between SSA locally residents and in the diasporan dwellers.

METHODS

This was a cross-sectional study conducted using a web and paper-based questionnaire to obtain relevant information on COVID-19 vaccine acceptance. The survey items included questions on demography, uptake and planned acceptance or non-acceptance of the COVID-19 vaccines among SSAs. Multinomial logistic regression was used to determine probabilities of outcomes for factors associated with COVID-19 vaccination resistance and hesitancy among SSA respondents residing within and outside Africa.

RESULTS

Uptake of COVID-19 vaccines varied among the local (14.2%) and diasporan (25.3%) dwellers. There were more locals (68.1%) who were resistant to COVID-19 vaccine. Participants' sex [adjusted relative risk (ARR) = 0.73, 95% CI: 0.58 - 0.93], education [primary/less: ARR = 0.22, CI:0.12 - 0.40, and bachelor's degree: ARR = 0.58, CI: 0.43 - 0.77]), occupation [ARR = 0.32, CI: 0.25-0.40] and working status [ARR = 1.40, CI: 1.06-1.84] were associated with COVID-19 vaccine resistance among locals. Similar proportion of local and diasporan dwellers (~ 18% each) were hesitant to COVID-19 vaccine, and this was higher among health care workers [ARR = 0.25, CI: 0.10 - 0.62 and ARR = 0.24, CI:0.18-0.32, diaspora and locals respectively]. After adjusting for the potential confounders, local residents aged 29-38 years [ARR = 1.89, CI: 1.26-2.84] and lived in East Africa [ARR = 4.64, CI: 1.84-11.70] were more likely to report vaccine hesitancy. Knowledge of COVID vaccines was associated with hesitancy among local and diasporan dwellers, but perception was associated with vaccine resistance [ARR = 0.86,CI: 0.82 - 0.90] and hesitancy [ARR = 0.85, CI: 0.80 - 0.90], only among the local residents.

CONCLUSIONS

Differences exist in the factors that influence COVID-19 vaccine acceptance between local SSA residents and thediasporan dwellers. Knowledge about COVID-19 vaccines affects the uptake, resistance, and hesitancy to the COVID-19 vaccine. Information campaigns focusing on the efficacy and safety of vaccines could lead to improved acceptance of COVID-19 vaccines.

Biological Sex and Pregnancy Affect Influenza Pathogenesis and Vaccination

Males and females differ in the outcome of influenza A virus (IAV) infections, which depends significantly on age. During seasonal influenza epidemics, young children (< 5 years of age) and aged adults (65+ years of age) are at greatest risk for severe disease, and among these age groups, males tend to suffer a worse outcome from IAV infection than females. Following infection with pandemic strains of IAVs, females of reproductive ages (i.e., 15-49 years of age) experience a worse outcome than their male counterparts. Although females of reproductive ages experience worse outcomes from IAV infection, females typically have greater immune responses to influenza vaccination as compared with males. Among females of reproductive ages, pregnancy is one factor linked to an increased risk of severe outcome of influenza. Small animal models of influenza virus infection and vaccination illustrate that immune responses and repair of damaged tissue following IAV infection also differ between the sexes and impact the outcome of infection. There is growing evidence that sex steroid hormones, including estrogens, progesterone, and testosterone, directly impact immune responses during IAV infection and vaccination. Greater consideration of the combined effects of sex and age as biological variables in epidemiological, clinical, and animal studies of influenza pathogenesis is needed.

Vaccination against influenza: Coverage and adherence in children under 15 years with high-risk medical conditions in the Community of Madrid

INTRODUCTION

Vaccination against influenza is indicated in children at risk of complications or severe disease. The objective of this study was to describe the percentage of children aged less than 15 years with risk conditions vaccinated against influenza in the Community of Madrid, and to analyze the factors associated with adherence to vaccination throughout 3 vaccination campaigns.

MATERIALS AND METHODS

Population-based cross-sectional observational study of children aged 6 months to 14 years with conditions that indicated influenza vaccination at the beginning of the 2018-2019 campaign. Electronic population registers were used. We described the percentage of children vaccinated in 3 consecutive campaigns, and assessed the association of adherence to vaccination with demographic and socioeconomic variables and risk conditions using bivariate and multivariate analysis.

RESULTS

The vaccination coverage was 15.6% in the 2018-2019 campaign. The adherence to vaccination was 65.9%. The variables associated with greater adherence were age greater than 2 years, especially in the 6-10 years group (aOR = 1.63; 95% CI, 1.43-1.85) and presenting more than one risk condition, especially 3 or more diseases (aOR = 1.80; 95% CI, 1.00-3.26). Diabetes mellitus was the disease associated most strongly with adherence (aOR = 2.15; 95% CI, 1.74-2.65). Adherence was lower in the immigrant population (aOR = 0.43; 95% CI, 0.36-0.51). We found no association between vaccination adherence and sex or socioeconomic status.

CONCLUSIONS

Vaccination coverage and adherence were suboptimal. Adherence to vaccination against influenza is associated with demographic and clinical conditions. Strategies need to be established to increase vaccination in children, with greater involvement of professionals and education of parents.

Effects of Biological Sex and Pregnancy on SARS-CoV-2 Pathogenesis and Vaccine Outcomes

SARS-CoV-2 is the causative agent of COVID-19 in humans and has resulted in the death of millions of people worldwide. Similar numbers of infections have been documented in males and females; males, however, are more likely than females to be hospitalized, require intensive care unit, or die from COVID-19. The mechanisms that account for this are multi-factorial and are likely to include differential expression of ACE2 and TMPRSS2 molecules that are required for viral entry into hosts cells and sex differences in the immune response, which are due to modulation of cellular functions by sex hormones and differences in chromosomal gene expression. Furthermore, as comorbidities are also associated with poorer outcomes to SARS-CoV-2 infection and several comorbidities are overrepresented in males, these are also likely to contribute to the observed sex differences. Despite their relative better prognosis following infection with SARS-CoV-2, females do have poorer outcomes during pregnancy. This is likely to be due to pregnancy-induced changes in the immune system that adversely affect viral immunity and disruption of the renin-angiotensin system. Importantly, vaccination reduces the severity of disease in males and females, including pregnant females, and there is no evidence that vaccination has any adverse effects on the outcomes of pregnancy.

Influenza Vaccination Coverage among Multiple Sclerosis Patients: Evolution over Time and Associated Factors

Our objective was to determine the influenza vaccination rate in a Spanish cohort of multiple sclerosis (MS) patients. A retrospective cohort study was carried out. Patients who attended the MS unit of the Lozano Blesa Hospital of Zaragoza between January 2015 and 2020 were included. The variables were obtained by reviewing the specialized and primary care records. Associations between receiving the vaccine in each flu season and the other variables were analyzed using bivariate analysis and multiple logistic regression models. A total of 260 patients were studied, with a median age of 31 years at the time of diagnosis. A total of 62.3% (162/260) were women. Vaccination coverage ranged from 20.4% in the 2015−2016 and 2016−2017 seasons to 41.5% in the 2019−2020 season (p = 0.000). Having been vaccinated in the previous season (ORa: 16.47−390.22; p = 0.000) and receiving a vaccination recommendation from the hospital vaccination unit (ORa: 2.44−3.96; p < 0.009) were associated with being vaccinated. The coverage is in an intermediate position compared to other countries. It is necessary to improve the referral system of these patients to the hospital vaccination unit because the information obtained by this service contributed to higher vaccination rates.

Side Effects of COVID-19 Inactivated Virus vs. Adenoviral Vector Vaccines: Experience of Algerian Healthcare Workers

Healthcare workers were prioritized in vaccination campaigns globally because they are exposed to the highest risk of contamination by SARS-CoV-2. This study evaluated the self-reported post-vaccination side effects of inactivated (BBIBP-CorV and CoronaVac) and adenoviral vector-based (AZD1222, Gam-COVID-Vac and Ad26.COV2.S) vaccines among Algerian healthcare workers using a validated questionnaire. The final analysis included 721 healthcare workers, with a predominance of females (59.1%) and younger individuals 20–30 years old (39.4%). Less than half (49.1%) of the respondents reported at least one local side effect, while 53.8% reported at least one systemic side effect. These side effects were more prevalent among viral vector vaccinees than inactivated virus vaccinees. The most common local side effects were injection site pain (39%) and arm pain (25.4%), while fatigue (34.4%), fever (28.4%), headache (24.8%) and myalgia (22.7%) were the most prevalent systemic side effects. The side effects appeared earlier among inactivated virus vaccines recipients and generally lasted for 2 to 3 days for the two vaccinated groups. The risk factors associated with a higher prevalence of side effects included female gender, allergic individuals, individuals with regular medication, those who contracted the COVID-19 disease and those who received two doses for both inactivated and viral-based vaccines groups. Despite the higher prevalence of post-vaccination side effects among adenoviral vector vaccines recipients, both vaccines groups were equally effective in preventing symptomatic infections, and no life-threatening side effects were reported in either vaccine group.

COVID-19 vaccine hesitancy in eight European countries: Prevalence, determinants, and heterogeneity

We examine heterogeneity in COVID-19 vaccine hesitancy across eight European countries. We reveal striking differences across countries, ranging from 6.4% of adults in Spain to 61.8% in Bulgaria reporting being hesitant. We experimentally assess the effectiveness of different messages designed to reduce COVID-19 vaccine hesitancy. Receiving messages emphasizing either the medical benefits or the hedonistic benefits of vaccination significantly increases COVID-19 vaccination willingness in Germany, whereas highlighting privileges contingent on holding a vaccination certificate increases vaccination willingness in both Germany and the United Kingdom. No message has significant positive effects in any other country. Machine learning-based heterogeneity analyses reveal that treatment effects are smaller or even negative in settings marked by high conspiracy beliefs and low health literacy. In contrast, trust in government increases treatment effects in some groups. The heterogeneity in vaccine hesitancy and responses to different messages suggests that health authorities should avoid one-size-fits-all vaccination campaigns.

Time Trends (2012-2020), Sex Differences and Predictors for Influenza Vaccination Uptake among Individuals with Chronic Obstructive Pulmonary Disease in Spain

(1) Background: To analyze time trends, sex differences, and factors associated with influenza vaccination uptake among individuals with COPD in Spain, 2012−2020. (2) Methods: A cross-sectional study based on data from the European Health Surveys for Spain, 2020 (EHSS2020) and 2014 and from the Spanish National Health Interview Surveys for 2017 and 2012. (3) Results: The study included 65,447 participants. Prevalence of COPD was 5.9% (n = 3855). Overall, the influenza vaccination uptake among COPD patients was 57.8% versus 28.6% for those without COPD (p < 0.001). Men with COPD reported higher uptake than women in all the surveys studied. Neither the crude nor the multivariable analysis showed a significant variation change overtime for people with COPD. However, among those aged <65 years, crude uptake decreased from 2012 to 2020 (39.4% vs. 33.3%; p = 0.039). Over the entire period, men were vaccinated significantly more than women (OR 1.28; 95% CI 1.12−1.47). Among COPD participants, included in the EHSS2020, independent predictors of vaccine uptake included being male, higher age, reporting no current smoking and suffering cancer or heart disease. (4) Conclusions: In COPD patients, the influenza vaccination uptake is below desirable levels and did not improve from 2012 to 2020. Sex differences are found, with consistent and constant lower uptake among women with COPD. The observed lower uptake among COPD women and patients with unhealthy lifestyle requires increased attention.

Influenza vaccination uptake among high-risk target groups and health care workers in Spain and change from 2017 to 2020

OBJECTIVE

Using the 2020 European Health Survey for Spain (EHSS2020), which ran from July 2019 to July 2020, we aimed to describe influenza vaccination uptake among the following target groups; individuals aged ≥65 years, health care workers (HCWs), and persons with high-risk chronic medical conditions. We analyzed changes in uptake since the previous Spanish National Health Interview Survey conducted in 2017 and identified variables associated with vaccine uptake.

METHODS

We performed a cross-sectional study. The primary study variable was the self-reported uptake of influenza vaccine in the previous year. We analyzed sex, age, country of birth, and being an HCW. We identified participants with self-reported respiratory diseases, cardiovascular disease, diabetes, cancer, and cerebrovascular diseases. Multivariable logistic regression was applied to assess changes over time and to identify variables associated with vaccination in target groups.

RESULTS

Uptake was 19.2% in 22,072 participants aged ≥15 years. Uptake was 54.4% for those aged ≥65 years, 41.6% for those with a high-risk medical condition, and 26.53% among HCWs. Uptake by disease was 52.1% for cerebrovascular diseases, 51.3% for cardiovascular diseases, 48.3% for diabetes, 46.1% for cancer, and 36.2% for respiratory diseases. No significant improvement has been observed since 2017 in any target group, except for participants with cancer, whose uptake increased from 33.2% to 46.1%(p < 0.001). The variables that significantly increased the probability of reporting vaccine uptake were female sex, age ≥35 years, being born in Spain, self-reported respiratory or cardiovascular diseases, diabetes, cancer, and being a HCW.

CONCLUSIONS

Influenza vaccination uptake among target groups in Spain is below desirable levels and has not improved significantly since 2017. Older age, female sex, and being born in Spain are positive predictors of vaccine uptake. The COVID-19 pandemic highlights the urgent need to implement new strategies to increase influenza vaccine uptake.

The Impact of Public Health Events on COVID-19 Vaccine Hesitancy on Chinese Social Media: National Infoveillance Study

BACKGROUND

The ongoing COVID-19 pandemic has brought unprecedented challenges to every country worldwide. A call for global vaccination for COVID-19 plays a pivotal role in the fight against this virus. With the development of COVID-19 vaccines, public willingness to get vaccinated has become an important public health concern, considering the vaccine hesitancy observed worldwide. Social media is powerful in monitoring public attitudes and assess the dissemination, which would provide valuable information for policy makers.

OBJECTIVE

This study aimed to investigate the responses of vaccine positivity on social media when major public events (major outbreaks) or major adverse events related to vaccination (COVID-19 or other similar vaccines) were reported.

METHODS

A total of 340,783 vaccine-related posts were captured with the poster's information on Weibo, the largest social platform in China. After data cleaning, 156,223 posts were included in the subsequent analysis. Using pandas and SnowNLP Python libraries, posts were classified into 2 categories, positive and negative. After model training and sentiment analysis, the proportion of positive posts was computed to measure the public positivity toward the COVID-19 vaccine.

RESULTS

The positivity toward COVID-19 vaccines in China tends to fluctuate over time in the range of 45.7% to 77.0% and is intuitively correlated with public health events. In terms of gender, males were more positive (70.0% of the time) than females. In terms of region, when regional epidemics arose, not only the region with the epidemic and surrounding regions but also the whole country showed more positive attitudes to varying degrees. When the epidemic subsided temporarily, positivity decreased with varying degrees in each region.

CONCLUSIONS

In China, public positivity toward COVID-19 vaccines fluctuates over time and a regional epidemic or news on social media may cause significant variations in willingness to accept a vaccine. Furthermore, public attitudes toward COVID-19 vaccination vary from gender and region. It is crucial for policy makers to adjust their policies through the use of positive incentives with prompt responses to pandemic-related news to promote vaccination acceptance.