Relative Effectiveness of the MF59®-Adjuvanted Influenza Vaccine Versus High-Dose and Non-Adjuvanted Influenza Vaccines in Preventing Cardiorespiratory Hospitalizations During the 2019-2020 US Influenza Season.

BACKGROUND: Adults ≥ 65 years of age have suboptimal influenza vaccination responses compared to younger adults due to age-related immunosenescence. Two vaccines were specifically developed to enhance protection: MF59-adjuvanted trivalent influenza vaccine (aIIV3) and high-dose egg-based trivalent influenza vaccine (HD-IIV3e). METHODS: In a retrospective cohort study conducted using US electronic medical records linked to claims data during the 2019-2020 influenza season, we compared the relative vaccine effectiveness (rVE) of aIIV3 with HD-IIV3e and a standard-dose non-adjuvanted egg-based quadrivalent inactivated influenza vaccine (IIV4e) for the prevention of cardiorespiratory hospitalizations, including influenza hospitalizations. We evaluated outcomes in the "any" diagnosis position and the "admitting" position on the claim. A doubly robust methodology using inverse probability of treatment weighting and logistic regression was used to adjust for covariate imbalance. rVE was calculated as 100 * (1 - ORadjusted). RESULTS: The study included 4,299,594 adults ≥ 65 years of age who received aIIV3, HD-IIV3e, or IIV4e. Overall, aIIV3 was associated with lower proportions of cardiorespiratory hospitalizations with diagnoses in any position compared to HD-IIV3e (rVE = 3.9% [95% CI, 2.7-5.0]) or IIV4e (9.0% [95% CI, 7.7-10.4]). Specifically, aIIV3 was more effective compared with HD-IIV3e and IIV4e in preventing influenza hospitalizations (HD-IIV3e: 9.7% [95% CI, 1.9-17.0]; IIV4e: 25.3% [95% CI, 17.7-32.2]). Consistent trends were observed for admitting diagnoses. CONCLUSION: Relative to both HD-IIV3e and IIV4e, aIIV3 provided improved protection from cardiorespiratory or influenza hospitalizations.

Anti-neuraminidase immunity in the combat against influenza.

INTRODUCTION: Anti-neuraminidase (NA) immunity correlates with the protection against influenza virus infection in both human and animal models. The aim of this review is to better understand the mechanism of anti-NA immunity, and also to evaluate the approaches on developing NA-based influenza vaccines or enhancing immune responses against NA for current influenza vaccines. AREAS COVERED: In this review, the structure of influenza neuraminidase, the contribution of anti-NA immunity to protection, as well as the efforts and challenges of targeting the immune responses to NA were discussed. We also listed some of the newly discovered anti-NA monoclonal antibodies and discussed their contribution in therapeutic as well as the antigen design of a broadly protective NA vaccine. EXPERT OPINION: Targeting the immune response to both HA and NA may be critical for achieving the optimal protection since there are different mechanisms of HA and NA elicited protective immunity. Monoclonal antibodies (mAbs) that target the conserved protective lateral face or catalytic sites are effective therapeutics. The epitope discovery using monoclonal antibodies may benefit NA-based vaccine elicited broadly reactive antibody responses. Therefore, the potential for a vaccine that elicits cross-reactive antibodies against neuraminidase is a high priority for next-generation influenza vaccines.

Recombinant parainfluenza virus 5 expressing clade 2.3.4.4b H5 hemagglutinin protein confers broad protection against H5Ny influenza viruses.

The global circulation of clade 2.3.4.4b H5Ny highly pathogenic avian influenza viruses (HPAIVs) in poultry and wild birds, increasing mammal infections, continues to pose a public health threat and may even form a pandemic. An efficacious vaccine against H5Ny HPAIVs is crucial for emergency use and pandemic preparedness. In this study, we developed a parainfluenza virus 5 (PIV5)-based vaccine candidate expressing hemagglutinin (HA) protein of clade 2.3.4.4b H5 HPAIV, termed rPIV5-H5, and evaluated its safety and efficacy in mice and ferrets. Our results demonstrated that intranasal immunization with a single dose of rPIV5-H5 could stimulate H5-specific antibody responses, moreover, a prime-boost regimen using rPIV5-H5 stimulated robust humoral, cellular, and mucosal immune responses in mice. Challenge study showed that rPIV5-H5 prime-boost regimen provided sterile immunity against lethal clade 2.3.4.4b H5N1 virus infection in mice and ferrets. Notably, rPIV5-H5 prime-boost regimen provided protection in mice against challenge with lethal doses of heterologous clades 2.2, 2.3.2, and 2.3.4 H5N1, and clade 2.3.4.4h H5N6 viruses. These results revealed that rPIV5-H5 can elicit protective immunity against a diverse clade of highly pathogenic H5Ny virus infection in mammals, highlighting the potential of rPIV5-H5 as a pan-H5 influenza vaccine candidate for emergency use.IMPORTANCEClade 2.3.4.4b H5Ny highly pathogenic avian influenza viruses (HPAIVs) have been widely circulating in wild birds and domestic poultry all over the world, leading to infections in mammals, including humans. Here, we developed a recombinant PIV5-vectored vaccine candidate expressing the HA protein of clade 2.3.4.4b H5 virus. Intranasal immunization with rPIV5-H5 in mice induced airway mucosal IgA responses, high levels of antibodies, and robust T-cell responses. Importantly, rPIV5-H5 conferred complete protection in mice and ferrets against clade 2.3.4.4b H5N1 virus challenge, the protective immunity was extended against heterologous H5Ny viruses. Taken together, our data demonstrate that rPIV5-H5 is a promising vaccine candidate against diverse H5Ny influenza viruses in mammals.

An intranasal influenza virus vector vaccine protects against Helicobacter pylori in mice.

Helicobacter pylori is a human pathogen that infects almost half of the population. Antibiotic resistance in H. pylori threatens health and increases the demand for prophylactic and therapeutic vaccines. Traditional oral vaccine research faces considerable challenges because of the epithelial barrier, potential enterotoxicity of adjuvants, and the challenging conditions of the gastric environment. We developed an intranasal influenza A virus (IAV) vector vaccine based on two live attenuated influenza viruses with modified acidic polymerase protein (PA) genes encoding the A subunit of H. pylori neutrophil-activating protein (NapA), named IAV-NapA, including influenza virus A/WSN/33 (WSN)-NapA and A/Puerto Rico/8/34 (PR8)-NapA. These recombinant influenza viruses were highly attenuated and exhibited strong immunogenicity in mice. Vaccination with IAV-NapA induced antigen-specific humoral and mucosal immune responses while stimulating robust Th1 and Th17 cell immune responses in mice. Our findings suggest that prophylactic and therapeutic vaccination with influenza virus vector vaccines significantly reduces colonization of H. pylori and inflammation in the stomach of mice.IMPORTANCEHelicobacter pylori is the most common cause of chronic gastritis and leads to severe gastroduodenal pathology in some patients. Many studies have shown that Th1 and Th17 cellular and gastric mucosal immune responses are critical in reducing H. pylori load. IAV vector vaccines can stimulate these immune responses while overcoming potential adjuvant toxicity and antigen dosing issues. To date, no studies have demonstrated the role of live attenuated IAV vector vaccines in preventing and treating H. pylori infection. Our work indicates that vaccination with IAV-NapA induces antigen-specific humoral, cellular, and mucosal immunity, producing a protective and therapeutic effect against H. pylori infection in BALB/c mice. This undescribed H. pylori vaccination approach may provide valuable information for developing vaccines against H. pylori infection.

COVID -19: On the threshold of the fifth year. The situation in Spain / COVID-19: A las puertas del quinto año

Despite having emerged from pandemic status, the incidence of COVID-19 episodes has recently increased in Spain, including pediatric cases and admissions to Intensive Care Units. Several recombinant variants are circulating among us, particularly XBB arising from two Omicron BA.2 sublineages with mutations in the genes encoding the spicule proteins that could increase binding to the ACE2 receptor and be more prone to immune escape. Faced with these, 3 pharmaceutical companies have developed vaccines adapted to the XBB.1.5 sublineage that are already available for administration in our setting with risks that should not be different from those of previous mRNA vaccines and with clearly favorable benefit/risk ratios. They should be applied to patients with potential for poor COVID-19 evolution and to collectives that have a particular relationship of proximity with them. Their application should be understood not only from a perspective of individual convenience but also from that of collective responsibility. The most convenient seems to be a simultaneous immunization of COVID-19 and influenza in our environment. In the therapeutic aspect, there is little to expect right now from antisera, but the already known antiviral drugs are still available and indicated, although their efficacy will have to be reevaluated due to their impact on populations that are mostly immunized and with a better prognosis than in the past. In our opinion, it is necessary to continue to make a reasonable and timely use of masks and other non-pharmacological means of protection. (AU)

Pese a haber salido de la situación de pandemia, la incidencia de episodios de COVID-19 ha aumentado recientemente en España, incluidos los casos pediátricos y los ingresos en Unidades de Cuidados Intensivos. Circulan entre nosotros diversas variantes recombinantes, particularmente la XBB surgidas de dos sublinajes Omicron BA.2 con mutaciones en los genes que codifican las proteínas de la espícula y que pudieran aumentar la unión al receptor ACE2 y ser más propensas al escape inmune. Frente a ellas, 3 empresas farmacéuticas han elaborado vacunas adaptadas al sublinaje XBB.1.5 que ya se encuentran disponibles para su administración en nuestro medio con riesgos que no deben ser diferentes a los de las vacunas mRNA previas y con relaciones beneficio/riesgos claramente favorables. Deben aplicarse a pacientes con potencial de mala evolución de COVID-19 y a los colectivos que tienen una particular relación de proximidad con ellos. Su aplicación debe ser entendida no sólo desde una perspectiva de conveniencia individual sino desde la de la responsabilidad colectiva. Lo más conveniente parece hacer una inmunización simultánea de COVID-19 y gripe en nuestro medio. En el aspecto terapéutico hay poco que esperar ahora mismo de los antisueros pero siguen estando disponibles e indicados los fármacos antivirales ya conocidos aunque su eficacia tendrá que reevaluarse por su impacto en poblaciones mayoritariamente inmunizadas y con pronóstico mejor que las de tiempos pasados. A nuestro juicio, es necesario seguir haciendo un uso razonable y puntual de mascarillas y otros medios no farmacológicos de protección. (AU)

Vaccination against influenza viruses reduces infection, not hospitalization or death, from respiratory COVID-19: A systematic review and meta-analysis.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes COVID-19 and has brought a huge burden in terms of human lives. Strict social distance and influenza vaccination have been recommended to avoid co-infections between influenza viruses and SARS-CoV-2. Scattered reports suggested a protective effect of influenza vaccine on COVID-19 development and severity. We analyzed 51 studies on the capacity of influenza vaccination to affect infection with SARS-CoV-2, hospitalization, admission to Intensive Care Units (ICU), and mortality. All subjects taken into consideration did not receive any anti-SARS-CoV-2 vaccine, although their status with respect to previous infections with SARS-CoV-2 is not known. Comparison between vaccinated and not-vaccinated subjects for each of the four endpoints was expressed as odds ratio (OR), with 95% confidence intervals (CIs); all analyses were performed by DerSimonian and Laird model, and Hartung-Knapp model when studies were less than 10. In a total of 61 029 936 subjects from 33 studies, influenza vaccination reduced frequency of SARS-CoV-2 infection [OR plus 95% CI = 0.70 (0.65-0.77)]. The effect was significant in all studies together, in health care workers and in the general population; distance from influenza vaccination and the type of vaccine were also of importance. In 98 174 subjects from 11 studies, frequency of ICU admission was reduced with influenza vaccination [OR (95% CI) = 0.71 (0.54-0.94)]; the effect was significant in all studies together, in pregnant women and in hospitalized subjects. In contrast, in 4 737 328 subjects from 14 studies hospitalization was not modified [OR (95% CI) = 1.05 (0.82-1.35)], and in 4 139 660 subjects from 19 studies, mortality was not modified [OR (95% CI) = 0.76 (0.26-2.20)]. Our study emphasizes the importance of influenza vaccination in the protection against SARS-CoV-2 infection.

Immunogenicity and safety of concomitant bivalent COVID-19 and quadrivalent influenza vaccination: implications of immune imprinting and interference.

OBJECTIVES: Concomitant COVID-19 and influenza vaccination would be an efficient strategy. Although the co-administration of monovalent COVID-19 and influenza vaccinations showed acceptable immunogenicity, it remains unknown whether the bivalent COVID-19 vaccine could intensify immune interference. We aimed to evaluate the immunogenicity and safety of concomitant BA.5-based bivalent COVID-19 and influenza vaccination. METHODS: An open-label, nonrandomized clinical trial was conducted for 154 age-matched and sex-matched healthy adults between October 2022 and December 2022. Participants received either a concomitant bivalent COVID-19 mRNA booster and quadrivalent influenza vaccination (group C) or separate vaccinations (group S) at least 4 weeks apart. Solicited and unsolicited adverse events were reported up to 6 months postvaccination. Immunogenicity was evaluated by anti-spike (S) IgG electrochemiluminescence immunoassay, focus reduction neutralization test, and hemagglutination inhibition assay. RESULTS: Group C did not meet the noninferiority criteria for the seroconversion rates of anti-S IgG and neutralizing antibodies against the wild-type SARS-CoV-2 strain compared with group S (44.2% vs. 46.8%, difference of -2.6% [95% CI, -18 to 13.4]; 44.2% vs. 57.1%, difference of -13.0% [95% CI to -28.9 to 2.9]). However, group C showed a stronger postvaccination neutralizing antibody response against Omicron BA.5 (72.7% vs. 64.9%). Postvaccination geometric mean titers for SARS-CoV-2 and influenza strains were similar between groups, except for influenza B/Victoria. Most adverse events were mild and comparable between the study groups. DISCUSSION: Concomitant administration of bivalent COVID-19 mRNA and quadrivalent influenza vaccines showed tolerable safety profiles and sufficient immunogenicity, particularly attenuating immune imprinting induced by previous ancestral vaccine strains.

Factors associated with shingles and pneumococcal vaccination among older Canadians.

Background: Immunization against vaccine-preventable diseases such as shingles and pneumococcal disease is especially pertinent among older Canadians. However, vaccine uptake remains low. Data and methods: Data from the Canadian Health Survey on Seniors (CHSS) - 2019/2020 were used to examine receipt of shingles and pneumococcal vaccines among Canadians aged 65 and older living in the community. Multivariable logistic regression was used to identify individual predisposing, enabling and needs-related factors associated with receipt of each type of vaccination. Reasons reported for not getting vaccinated were also examined. Results: Based on the 2019/2020 CHSS, an estimated 36.3% of Canadians aged 65 and older (2.3 million people) had received the shingles vaccine, while 51.1% (3.1 million) had received the pneumococcal vaccine. Being a woman, having higher socioeconomic status, having had the flu shot and having a regular health care provider were associated with increased odds of vaccination. Being an immigrant, living outside large population centres, and belonging to South Asian or Chinese population groups were associated with lower odds of vaccination. Over one-third of unvaccinated people did not think the shingles vaccine (39.7%) or the pneumococcal vaccine (36.6%) was necessary. Other frequently reported reasons for non-vaccination were not having heard of the vaccine or the doctor not mentioning it; for the shingles vaccine, 12% cited cost as a reason. Interpretation: Understanding factors associated with uptake of vaccines and reasons for not obtaining them among older Canadians will help to inform policy and programs aimed at preventing the burden of these diseases.

Concomitant administration of seasonal influenza and COVID-19 mRNA vaccines.

Current clinical guidelines support the concomitant administration of seasonal influenza vaccines and COVID-19 mRNA boosters vaccine. Whether dual vaccination may impact vaccine immunogenicity due to an interference between influenza or SARS-CoV-2 antigens is unknown. We aimed to understand the impact of mRNA COVID-19 vaccines administered concomitantly on the immune response to influenza vaccines. For this, 128 volunteers were vaccinated during the 22-23 influenza season. Three groups of vaccination were assembled: FLU vaccine only (46, 35%) versus volunteers that received the mRNA bivalent COVID-19 vaccines concomitantly to seasonal influenza vaccines, FluCOVID vaccine in the same arm (42, 33%) or different arm (40, 31%), respectively. Sera and whole blood were obtained the day of vaccination, +7, and +28 days after for antibody and T cells response quantification. As expected, side effects were increased in individuals who received the FluCOVID vaccine as compared to FLU vaccine only based on the known reactogenicity of mRNA vaccines. In general, antibody levels were high at 4 weeks post-vaccination and differences were found only for the H3N2 virus when administered in different arms compared to the other groups at day 28 post-vaccination. Additionally, our data showed that subjects that received the FluCOVID vaccine in different arm tended to have better antibody induction than those receiving FLU vaccines for H3N2 virus in the absence of pre-existing immunity. Furthermore, no notable differences in the influenza-specific cellular immune response were found for any of the vaccination groups. Our data supports the concomitant administration of seasonal influenza and mRNA COVID-19 vaccines.

Altered liver function test after Covid-19 vaccines: A retrospective control group study.

BACKGROUND AND PURPOSE: Liver injury after Covid-19 vaccine has been described, although the incidence was not well established. We aimed to compare cumulative incidence of new onset liver test alteration after Covid-19 vaccination, and to compare with an historical control of influenza vaccination. METHODS: We conducted a retrospective cohort study which included adults who received at least one dose of Covid-19 vaccine from January 1 to May 30, 2021 and a control group who received a single dose of influenza vaccine during 2019, in a tertiary medical center from Argentina. RESULTS: We included 29 798 patients in Covid-19 vaccine group and 24 605 in influenza vaccine group. Liver function tests were performed in 7833 (26.9%) in Covid-19 vaccine group and 8459 (34.37%) in influenza vaccine group. Cumulative incidence at 90 days of new onset liver enzyme test alteration was 4.7 per 1000 (95% 4.0-5.5) for Covid-19 group, and 5.1 per 1000 (95% 4.3-6.1) for the influenza vaccine group (p value = 0.489). Two patients in the Covid-19 vaccine group developed immune mediated liver injury. CONCLUSIONS: We found no difference in liver test alteration between groups. These findings support the safety of Covid-19 vaccines. While we have identified two cases that are consistent with immune mediated liver injury following COVID-19 vaccination, we believe that the available data is insufficient to attribute them solely to the vaccination.

Unpacking Intersectional Inequities in Flu Vaccination by Sexuality, Gender, and Race-Ethnicity in the United States.

Health care research has long overlooked the intersection of multiple social inequalities. This study examines influenza vaccination inequities at the intersection of sexuality, gender, and race-ethnicity. Using data from the 2013 to 2018 National Health Interview Survey (N = 166,908), the study shows that sexual, gender, and racial-ethnic identities jointly shaped flu vaccination. Specifically, White gay men had the highest vaccination rate (56%), while Black bisexual women had the lowest rate (23%). Across Black, Hispanic, and White individuals, sexual minority women had lower vaccination rates than heterosexual women, but sexual minority men had higher or similar vaccination rates than heterosexual men. Economic enabling, noneconomic enabling, and need-based factors together explained a substantial portion of these gaps. However, they cannot explain all the disadvantages faced by Black lesbian, bisexual, and heterosexual women and Black heterosexual men. Findings offer new evidence of hidden health care inequities and inform health policies from an intersectional perspective.

Maternal Vaccine Effectiveness Against Influenza-Associated Hospitalizations and Emergency Department Visits in Infants.

Importance: Influenza virus infection during pregnancy is associated with severe maternal disease and may be associated with adverse birth outcomes. Inactivated influenza vaccine during pregnancy is safe and effective and can protect young infants, but recent evidence, particularly after the 2009 novel influenza A (H1N1) pandemic, is limited. Objective: To evaluate the effectiveness of influenza vaccination during pregnancy against laboratory-confirmed influenza-associated hospitalizations and emergency department (ED) visits in infants younger than 6 months. Design, Setting, and Participants: This was a prospective, test-negative case-control study using data from the New Vaccine Surveillance Network from the 2016 to 2017 through 2019 to 2020 influenza seasons. Infants younger than 6 months with an ED visit or hospitalization for acute respiratory illness were included from 7 pediatric medical institutions in US cities. Control infants with an influenza-negative molecular test were included for comparison. Data were analyzed from June 2022 to September 2023. Exposure: Maternal influenza vaccination during pregnancy. Main Outcomes and Measures: We estimated maternal vaccine effectiveness against hospitalizations or ED visits in infants younger than 6 months, those younger than 3 months, and by trimester of vaccination. Maternal vaccination status was determined using immunization information systems, medical records, or self-report. Vaccine effectiveness was estimated by comparing the odds of maternal influenza vaccination 14 days or more before delivery in infants with influenza vs those without. Results: Of 3764 infants (223 with influenza and 3541 control infants), 2007 (53%) were born to mothers who were vaccinated during pregnancy. Overall vaccine effectiveness in infants was 34% (95% CI, 12 to 50), 39% (95% CI, 12 to 58) against influenza-associated hospitalizations, and 19% (95% CI, -24 to 48) against ED visits. Among infants younger than 3 months, effectiveness was 53% (95% CI, 30 to 68). Effectiveness was 52% (95% CI, 30 to 68) among infants with mothers who were vaccinated during the third trimester and 17% (95% CI, -15 to 40) among those with mothers who were vaccinated during the first or second trimesters. Conclusions and Relevance: Maternal vaccination was associated with reduced odds of influenza-associated hospitalizations and ED visits in infants younger than 6 months. Effectiveness was greatest among infants younger than 3 months, for those born to mothers vaccinated during the third trimester, and against influenza-associated hospitalizations.

Having a real say: findings from first nations community panels on pandemic influenza vaccine distribution.

BACKGROUND: Recent deliberations by Australian public health researchers and practitioners produced an ethical framework of how decisions should be made to distribute pandemic influenza vaccine. The outcome of the deliberations was that the population should be considered in two categories, Level 1 and Level 2, with Level 1 groups being offered access to the pandemic influenza vaccine before other groups. However, the public health researchers and practitioners recognised the importance of making space for public opinion and sought to understand citizens values and preferences, especially First Nations peoples. METHODS: We conducted First Nations Community Panels in two Australian locations in 2019 to assess First Nations people's informed views through a deliberative process on pandemic influenza vaccination distribution strategies. Panels were asked to make decisions on priority levels, coverage and vaccine doses. RESULTS: Two panels were conducted with eighteen First Nations participants from a range of ages who were purposively recruited through local community networks. Panels heard presentations from public health experts, cross-examined expert presenters and deliberated on the issues. Both panels agreed that First Nations peoples be assigned Level 1 priority, be offered pandemic influenza vaccination before other groups, and be offered two doses of vaccine. Reasons for this decision included First Nations people's lives, culture and families are important; are at-risk of severe health outcomes; and experience barriers and challenges to accessing safe, quality and culturally appropriate healthcare. We found that communication strategies, utilising and upskilling the First Nations health workforce, and targeted vaccination strategies are important elements in pandemic preparedness and response with First Nations peoples. CONCLUSIONS: First Nations Community Panels supported prioritising First Nations peoples for pandemic influenza vaccination distribution and offering greater protection by using a two-dose full course to fewer people if there are initial supply limitations, instead of one dose to more people, during the initial phase of the vaccine roll out. The methodology and findings can help inform efforts in planning for future pandemic vaccination strategies for First Nations peoples in Australia.

Recombinant or Standard-Dose Influenza Vaccine in Adults under 65 Years of Age.

BACKGROUND: Quadrivalent recombinant influenza vaccines contain three times the amount of hemagglutinin protein as standard-dose egg-based vaccines, and the recombinant formulation is not susceptible to antigenic drift during manufacturing. Data are needed on the relative effectiveness of recombinant vaccines as compared with standard-dose vaccines against influenza-related outcomes in adults under the age of 65 years. METHODS: In this cluster-randomized observational study, Kaiser Permanente Northern California facilities routinely administered either a high-dose recombinant influenza vaccine (Flublok Quadrivalent) or one of two standard-dose influenza vaccines during the 2018-2019 and 2019-2020 influenza seasons to adults 50 to 64 years of age (primary age group) and 18 to 49 years of age. Each facility alternated weekly between the two vaccine formulations. The primary outcome was influenza (A or B) confirmed by polymerase-chain-reaction (PCR) testing. Secondary outcomes included influenza A, influenza B, and influenza-related hospitalization outcomes. We used Cox regression analysis to estimate the hazard ratio of the recombinant vaccine as compared with the standard-dose vaccines against each outcome. We calculated the relative vaccine effectiveness as 1 minus the hazard ratio. RESULTS: The study population included 1,630,328 vaccinees between the ages of 18 and 64 years (632,962 in the recombinant-vaccine group and 997,366 in the standard-dose group). During this study period, 1386 cases of PCR-confirmed influenza were diagnosed in the recombinant-vaccine group and 2435 cases in the standard-dose group. Among the participants who were 50 to 64 years of age, 559 participants (2.00 cases per 1000) tested positive for influenza in the recombinant-vaccine group as compared with 925 participants (2.34 cases per 1000) in the standard-dose group (relative vaccine effectiveness, 15.3%; 95% confidence interval [CI], 5.9 to 23.8; P = 0.002). In the same age group, the relative vaccine effectiveness against influenza A was 15.7% (95% CI, 6.0 to 24.5; P = 0.002). The recombinant vaccine was not significantly more protective against influenza-related hospitalization than were the standard-dose vaccines. CONCLUSIONS: The high-dose recombinant vaccine conferred more protection against PCR-confirmed influenza than an egg-based standard-dose vaccine among adults between the ages of 50 and 64 years. (Funded by Sanofi; ClinicalTrials.gov number, NCT03694392.).

Racial and ethnic disparities in influenza vaccination coverage among pregnant women in the United States: The contribution of vaccine-related attitudes.

OBJECTIVE: Racial and ethnic disparities in influenza vaccination coverage among pregnant women in the United States have been documented. This study assessed the contribution of vaccine-related attitudes to coverage disparities. METHODS: Surveys were conducted following the 2019-2020 and 2020-2021 influenza seasons in a US research network. Using electronic health record data to identify pregnant women, random samples were selected for surveying; non-Hispanic Black women and influenza-unvaccinated women were oversampled. Regression-based decomposition analyses were used to assess the contribution of vaccine-related attitudes to racial and ethnic differences in influenza vaccination. Data were combined across survey years, and analyses were weighted and accounted for survey design. RESULTS: Survey response rate was 41.2% (721 of 1748) for 2019-2020 and 39.3% (706 of 1798) for 2020-2021. Self-reported influenza vaccination was higher among non-Hispanic White respondents (79.4% coverage, 95% CI 73.1%-85.7%) than Hispanic (66.2% coverage, 95% CI 52.5%-79.9%) and non-Hispanic Black (55.8% coverage, 95% CI 50.2%-61.4%) respondents. For all racial and ethnic groups, a high proportion (generally >80%) reported being seen for care, recommended for influenza vaccination, and offered vaccination. In decomposition analyses, vaccine-related attitudes (e.g., worry about vaccination causing influenza; concern about vaccine safety and effectiveness) explained a statistically significant portion of the observed racial and ethnic disparities in vaccination. Maternal age, education, and health status were not significant contributors after controlling for vaccine-related attitudes. CONCLUSIONS: In a setting with relatively high influenza vaccination coverage among pregnant women, racial and ethnic disparities in coverage were identified. Vaccine-related attitudes were associated with the disparities observed.

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.

Association between acceptance of routine pregnancy vaccinations and COVID-19 vaccine uptake in pregnant patients.

OBJECTIVE: COVID-19 vaccination is a key approach to reduce morbidity and mortality in pregnant patients and their newborns. Anti-vaccine sentiment has recently increased with unclear impact on pregnant patients. We examined the association between acceptance of tetanus-diphtheria-acellular pertussis (Tdap) and influenza vaccines, considered to be routine pregnancy vaccines, and COVID-19 vaccine acceptance. Secondarily, we identified other predictors of COVID-19 vaccine uptake and described pregnancy outcomes in patients who were and were not vaccinated during pregnancy. METHODS: A retrospective cohort study of all patients who delivered at a single site from December 2020 - March 2022. Demographic, pregnancy, neonatal, and vaccination data were abstracted from the electronic medical record, which imports vaccine history from the California Immunization Registry. The relationship between influenza and Tdap vaccine acceptance, other baseline characteristics, and COVID-19 vaccine uptake was assessed using univariable and multivariable regression analysis. RESULTS: Of the 7857 patients who delivered during the study period, 4410 (56.1%) accepted the COVID-19 vaccine. Of those who received the COVID-19 vaccine, 3363 (97.6%) and 3049 (88.5%) received influenza and Tdap vaccines, respectively. Patients were more likely to receive the COVID-19 vaccine if they had advanced maternal age, obesity, Asian race, and private insurance. After adjustment for baseline differences, COVID vaccine acceptance was associated with receipt of Tdap (aOR 2.10, 95% CI 1.90-2.33) and influenza vaccines (aOR 2.83, 95% CI 2.55-3.14). There were no differences in preterm birth, low birthweight, and NICU admission between patients who received and did not receive the COVID-19 vaccine. CONCLUSION: Patients were more likely to accept COVID-19 vaccination if they received Tdap or influenza vaccinations. Older age, obesity, Asian race, and private insurance were independent predictors of vaccine uptake. Disparities in COVID-19 vaccination uptake bear further exploration to guide efforts in equitable and widespread vaccine distribution.