Coadministration of seasonal influenza and COVID-19 vaccines: A systematic review of clinical studies

Trends in the administration of COVID-19 vaccines with other vaccines in the United States reported to V-safe during December 14, 2020-May 19, 2023

Introduction COVID-19 vaccines may be administered with other vaccines during the same healthcare visit. COVID-19 monovalent (Fall 2021) and bivalent (Fall 2022) vaccine recommendations coincided with annual seasonal influenza vaccination. Data describing the frequency of the co-administration of COVID-19 vaccines with other vaccines are limited. Methods We used V-safe, a voluntary smartphone-based U.S. safety surveillance system established by the CDC, to describe trends in the administration of COVID-19 vaccines with other vaccines reported to V-safe during December 14, 2020 - May 19, 2023. Results Of the 21 million COVID-19 vaccinations reported to V-safe, 2.2% (459,817) were administered with at least 1 other vaccine. Co-administration most frequently occurred during the first week of October 2023 (27,092; 44.1%). Most reports of co-administration included influenza vaccine (393,003; 85.5%). Co-administration was most frequently reported for registrants aged 6 months-6 years (4,872; 4.4%). Conclusion Reports of co-administration to V-safe peaked during October 2023, when influenza vaccination most often occurs, possibly reflecting increased opportunities for multiple vaccinations and greater acceptability of the co-administration of COVID-19 vaccine with other vaccines, especially influenza vaccine.

Vaccination status and disease severity of COVID-19 in different phases of the pandemic

This study aimed to explore the clinical profile and the impact of vaccination status on various health outcomes among COVID-19 patients diagnosed in different phases of the pandemic, during which several variants of concern (VOCs) circulated in South Carolina (SC). The current study included 861,526 adult COVID-19 patients diagnosed between January 2021 and April 2022. We extracted their information about demographic characteristics, vaccination, and clinical outcomes from a statewide electronic health record database. Multiple logistic regression models were used to compare clinical outcomes by vaccination status in different pandemic phases, accounting for key covariates (e.g. historical comorbidities). A reduction in mortality was observed among COVID-19 patients during the whole study period, although there were fluctuations during the Delta and Omicron dominant periods. Compared to non-vaccinated patients, full-vaccinated COVID-19 patients had lower mortality in all dominant variants, including Pre-alpha (adjusted odds ratio [aOR]: 0.33; 95%CI: 0.15-0.72), Alpha (aOR: 0.58; 95%CI: 0.42-0.82), Delta (aOR: 0.28; 95%CI: 0.25-0.31), and Omicron (aOR: 0.29; 95%CI: 0.26-0.33) phases. Regarding hospitalization, full-vaccinated parties showed lower risk of hospitalization than non-vaccinated patients in Delta (aOR: 0.44; 95%CI: 0.41-0.47) and Omicron (aOR: 0.53; 95%CI: 0.50-0.57) dominant periods. The findings demonstrated the protection effect of the COVID-19 vaccines against all VOCs, although some of the full-vaccinated population still have symptoms to varying degrees from COVID-19 disease at different phases of the pandemic.

Association between combination COVID-19-influenza vaccination and long COVID in middle-aged and older Europeans: A cross-sectional study

The potential impact of combined COVID-19 and influenza vaccination on long COVID remains uncertain. In the present cross-sectional study, we aimed to investigate the plausible association between them in middle-aged and older Europeans based on the Survey of Health, Ageing, and Retirement in Europe (SHARE). A total of 1910 participants were recruited in the analyses. The study outcome was long COVID. Participants were divided into 4 groups through the self-reported status of COVID-19 and influenza vaccination. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated. 1397 participants experienced long COVID. After multivariable adjustment, those vaccinated with neither COVID-19 nor influenza vaccine had higher risk of long COVID (OR, 1.72; 95% CI, 1.26-2.35) compared to those vaccinated with both vaccines. Furthermore, adding the 4 statuses of COVID-19 vaccination/influenza vaccination to conventional risk model improved risk reclassification for long COVID (continuous net reclassification improvement was 16.26% [p = .003], and integrated discrimination improvement was 0.51% [p = .005]). No heterogeneity was found in the subgroup analyses (all p-interaction ≥0.05). Our study might provide a strategy for people aged 50 and over to reduce the occurrence of long COVID, that is, to combine the use of the COVID-19 vaccine and influenza vaccines.

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.

Depression and vaccination behavior in patients with chronic physical illness - A cross-sectional survey

OBJECTIVE

Chronically ill are vulnerable to vaccine preventable infections. Consequently, their vaccination behavior is highly relevant. Depressive comorbidities are frequent in these patients. Furthermore, these patients are mainly diagnosed, treated and vaccinated in primary care. Therefore, we aimed to investigate the associations between depression and vaccination behavior (COVID-19 and influenza) in adult chronically ill primary care patients.

METHODS

In a cross-sectional survey, we examined depression (PHQ9), psychological antecedents of vaccinations (Confidence and Constraints), health care utilization, and vaccination status. Based on an effect model, descriptive statistics and mixed linear/logistic models were calculated. (German Clinical Trials Register, DRKS00030042).

RESULTS

n = 795 patients were analyzed. Both psychological antecedents of vaccinations (Confidence and Constraints) mediated a negative association between depression and vaccination behavior, healthcare utilization mediated a positive association. The total effect of depression was negligible.

CONCLUSIONS

As the effects of vaccination readiness and healthcare utilization are opposing, different total effects depending on the study population are possible. Further studies are needed to investigate additional predictors of vaccination behavior.

PRACTICE IMPLICATIONS

We suggest tackling vaccine acceptance in chronically ill through increasing confidence using communication-based interventions, for which primary care is the suitable setting. Constraints might be reduced by reminder and recall systems.

Recommendations for Prevention and Control of Influenza in Children, 2024-2025: Technical Report

This technical report accompanies the recommendations of the American Academy of Pediatrics for the routine use of influenza vaccine and antiviral medications in the prevention and treatment of influenza in children during the 2024 to 2025 season. The rationale for the American Academy of Pediatrics recommendation for annual influenza vaccination of all children without medical contraindications starting at 6 months of age is provided. Influenza vaccination is an important strategy for protecting children and the broader community against influenza. This technical report summarizes recent influenza seasons, morbidity and mortality in children, vaccine effectiveness, and vaccination coverage and provides detailed guidance on vaccine storage, administration, and implementation. The report also provides a brief background on inactivated (nonlive) and live attenuated influenza vaccines, available vaccines for the 2024-2025 influenza season, vaccination during pregnancy and breastfeeding, diagnostic testing for influenza, and antiviral medications for treatment and chemoprophylaxis. Strategies to promote vaccine uptake are emphasized.

A Serum Multi-Parametric Analysis Identifies an Early Innate Immune Signature Associated to Increased Vaccine-Specific Antibody Production and Seroconversion in Simultaneous COVID-19 mRNA and Cell-Based Quadrivalent Influenza Vaccination

In this pilot study, a multi-parametric analysis comparing immune responses in sera of adult healthy subjects (HS) or people with type 2 diabetes mellitus (T2D) undergoing the single or simultaneous administration of mRNA-based COVID-19 and cellular quadrivalent inactivated influenza vaccines was conducted. While SARS-CoV-2 antibodies remains comparable, influenza antibody titers and seroconversion were significantly higher upon simultaneous vaccination. Magnitude of anti-influenza humoral response closely correlated with an early innate immune signature, previously described for the COVID-19 vaccine, composed of IL-15, IL-6, TNF-α, IFN-γ, CXCL-10 and here extended also to acute-phase protein Pentraxin 3. People with T2D receiving simultaneous vaccination showed a protective response comparable to HS correlating with the early induction of IFN-γ/CXCL10 and a significant reduction of the circulating glucose level due to increased oxidation of glucose digestion and consumption. These data, although preliminary and in-need of validation in larger cohorts, might be exploited to optimize future vaccination in people with chronic disorders, including diabetes.

Enhancing COVID-19 Vaccination Awareness and Uptake in the Post-PHEIC Era: A Narrative Review of Physician-Level and System-Level Strategies

Following the World Health Organization's declaration that the COVID-19 pandemic is no longer a public health emergency of international concern (PHEIC), COVID-19 remains an ongoing threat to human health and healthcare systems. Vaccination plays a crucial role in reducing the disease's incidence, mitigating its severity, and limiting transmission, contributing to long-term public health resilience. However, incomplete vaccination coverage and vaccine hesitancy exist. This narrative review investigates strategies at the system and physician levels aimed at sustaining awareness and uptake of COVID-19 vaccination in a post-PHEIC era. Through an examination of the existing literature, this review explores the effectiveness of diverse approaches utilized by healthcare systems and individual providers. These approaches address every component of the 5C model of vaccine hesitancy: confidence, complacency, constraints/convenience, calculation, and collective responsibility. Physician-level approaches include appropriate message framing, persuasive communication containing safety and personal/social benefit information, sharing of personal stories, creating a safe space for discussion, harnessing co-administration with annual influenza vaccines, and use of decision aids and visual messages. System-level approaches include messaging, mass media for health communication, on-site vaccine availability, pharmacist delivery, healthcare protocol integration, incentives, and chatbot use.

COVID-19 and Influenza Vaccine Coadministration Among Older U.S. Adults

INTRODUCTION

Coadministering COVID-19 and influenza vaccines is recommended by public health authorities and intended to improve uptake and convenience; however, the extent of vaccine coadministration is largely unknown. Investigations into COVID-19 and influenza vaccine coadministration are needed to describe compliance with newer recommendations and to identify potential gaps in the implementation of coadministration.

METHODS

A descriptive, repeated cross-sectional study between September 1, 2021 to November 30, 2021 (Period 1) and September 1, 2022 to November 30, 2022 (Period 2) was conducted. This study included community-dwelling Medicare beneficiaries ≥ 66 years who received an mRNA COVID-19 booster vaccine in Periods 1 and 2. The outcome was an influenza vaccine administered on the same day as the COVID-19 vaccine. Adjusted ORs and 99% CIs were estimated using logistic regression to describe the association between beneficiaries' characteristics and vaccine coadministration. Statistical analysis was performed in 2023.

RESULTS

Among beneficiaries who received a COVID-19 vaccine, 78.8% in Period 1 (N=6,292,777) and 89.1% in Period 2 (N=4,757,501), received an influenza vaccine at some point during the study period (i.e., before, after, or on the same day as their COVID-19 vaccine), though rates were lower in non-White and rural individuals. Vaccine coadministration increased from 11.1% to 36.5% between periods. Beneficiaries with dementia (aORPeriod 2=1.31; 99%CI=1.29-1.32) and in rural counties (aORPeriod 2=1.19; 99%CI=1.17-1.20) were more likely to receive coadministered vaccines, while those with cancer (aORPeriod 2=0.90; 99%CI=0.89-0.91) were less likely.

CONCLUSIONS

Among Medicare beneficiaries vaccinated against COVID-19, influenza vaccination was high, but coadministration of the 2 vaccines was low. Future work should explore which factors explain variation in the decision to receive coadministered vaccines.

Ipsilateral and contralateral coadministration of influenza and COVID-19 vaccines produce similar antibody responses

BACKGROUND

World Health Organisation (WHO) and USA Centers for Disease Control and Prevention (U.S. CDC) recommendations now allow simultaneous administration of COVID-19 and other vaccines. We compared antibody responses after coadministration of influenza and bivalent COVID-19 vaccines in the same (ipsilateral) arm vs. different (contralateral) arms.

METHODS

Pre- and post-vaccination serum samples from individuals in the Prospective Assessment of COVID-19 in a Community (PACC) cohort were used to conduct haemaglutination inhibition (HI) assays with the viruses in the 2022-2023 seasonal influenza vaccine and focus reduction neutralisation tests (FRNT) using a BA.5 SARS-CoV-2 virus. The effect of ipsilateral vs. contralateral vaccination on immune responses was inferred in a model that accounted for higher variance in vaccine responses at lower pre-vaccination titers.

FINDINGS

Ipsilateral vaccination did not cause higher influenza vaccine responses compared to contralateral vaccination. The response to SARS-CoV-2 was slightly increased in the ipsilateral group, but equivalence was not excluded.

INTERPRETATION

Coadministration of influenza and bivalent COVID-19 vaccines in the same arm or different arms did not strongly influence the antibody response to either vaccine.

FUNDING

This work was supported by the U.S. CDC (grant number: 75D30120C09259).

Co-Administration of Influenza and COVID-19 Vaccines: Policy Review and Vaccination Coverage Trends in the European Union, UK, US, and Canada between 2019 and 2023

Recommending co-administration of influenza and COVID-19 vaccines has emerged as a strategy to enhance vaccination coverage. This study describes the policy on co-administration and uptake of influenza and COVID-19 vaccination in Europe, the United Kingdom, the United States, and Canada between 2019 and 2023. We collected co-administration policy data from governmental websites, national health organizations, and newspapers. Influenza vaccination coverage among persons ≥65 years and COVID-19 vaccination coverage rates among persons ≥60 years or the general population were collected using national databases, the ECDC database, or ourworldindata.org between 2019 and 2023. Descriptive analyses were used. We collected data from 30/32 (94%) countries on vaccination policy in seasons 2021-2022 and 2022-2023, with most countries (25/30 to 30/30) having policies recommending co-administration. For influenza vaccination coverage, we collected data from 29/32 (91%, 2019-2020), 28/32 (88%, 2020-2021), 27/32 (84%, 2021-2022), and 6/32 (19%, 2022-2023) countries. COVID-19 vaccination was collected from 32/32 (2020-2021), 31/32 (97%, 2021-2022), and 24/32 (75%, 2022-2023) countries. Influenza vaccination coverage increased from 2019-2020 to 2021-2022. COVID-19 vaccination coverage was higher among countries with higher influenza vaccination coverage. By 2022-2023, all countries included implemented a policy supporting co-administration. A positive correlation existed between higher influenza vaccination coverage and higher COVID-19 vaccination rates.

COVID-19: On the threshold of the fifth year. The situation in Spain

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.

Co-administration of SARS-CoV-2 and influenza vaccines in healthcare workers: Results of two vaccination campaigns in a large teaching hospital in Rome

The concurrent administration of COVID-19 and influenza vaccines has arisen as a promising approach to bolster protection against respiratory pathogens and improve vaccination rates. However, there remains a lack of data regarding the prevalence of co-administration across several vaccination campaigns, especially among healthcare workers (HCWs). Therefore, this study aims to shed light on the acceptance of co-administration strategies among HCWs during the two campaigns following the introduction of the anti-SARS-CoV-2 vaccine. A retrospective cohort study was conducted among the HCWs of the Fondazione Policlinico Universitario "A. Gemelli" IRCCS, a research hospital in Rome. Hospital administrative databases were accessed to gather information about vaccination for SARS-CoV-2 and influenza during the 2021/2022 and 2022/2023 vaccination campaigns. The study included 7399 HCWs. The co-administration of anti-SARS-CoV-2 and influenza vaccines presented a significant rise in 2022/2023 compared to the previous vaccination campaign (+38%): this was confirmed for every professional category, with the largest increases among resident doctors (+47%) and physicians (+44%), and also for every age category, but it was particularly evident for the youngest health professionals. The probability of co-administration uptake during the 2022/2023 campaign was significantly higher for males, and for those that received co-administration during the 2021/2022 campaign, while the probability was lower for nurses and administrative staff. This study highlights the co-administration procedure as a valuable and effective tool in annual vaccination campaigns for SARS-CoV-2 and influenza. The procedure's safety and streamlined logistics make it increasingly attractive for implementation, particularly among HCWs.

A single blinded, phase IV, adaptive randomised control trial to evaluate the safety of coadministration of seasonal influenza and COVID-19 vaccines (The FluVID study)

OBJECTIVES

We evaluated the frequency of moderate and severe adverse events following coadministration of seasonal influenza vaccine (SIV) versus placebo with COVID-19 vaccines among adults to support practice guidelines.

METHODS

FluVID is a participant-blinded, phase IV, randomised control trial. On the same day as the participant's scheduled COVID-19 vaccine, participants were randomised to receive SIV or saline placebo; those assigned placebo at visit one then received SIV a week later, and vice versa. Self-reported adverse events were collected daily for seven days following each visit. The primary endpoint was any solicited adverse event of at least moderate severity occurring up to seven days following receipt of SIV or placebo. This was modelled using a Bayesian logistic regression model. Analyses were performed by COVID-19 vaccine type and dose number.

RESULTS

Overall, 248 participants were enrolled; of these, 195 had received BNT162b2 and 53 had received mRNA1273 COVID-19 vaccines according to national guidelines. After randomisation, 119 were assigned to receive SIV and 129 were assigned to receive placebo at visit one. Adverse events were most frequently reported as mild (grade 1) in nature. Among 142 BNT162b2 booster dose one and 43 BNT162b2 booster dose two recipients, the posterior median risk difference for moderate/severe adverse events following SIV versus placebo was 13% (95% credible interval [CrI] -0.03 to 0.27) and 13% (95%CrI -0.37 to 0.12), respectively. Among 18 mRNA1273 booster dose one and 35 mRNA1273 booster dose two recipients, the posterior median risk difference of moderate/severe adverse events following influenza vaccine versus placebo was 6% (95%CrI -0.29 to 0.41) and -4% (95%CrI -0.30 to 0.23), respectively.

CONCLUSION

Adverse events following SIV and COVID-19 co-administration were generally mild and occurred with similar frequency to events following COVID-19 vaccine alone. We found no evidence to justify routine separation of SIV and COVID-19 vaccine doses.

CLINICAL TRIAL REGISTRATION

ACTRN12621001063808.

Estimated Effectiveness of Coadministration of the BNT162b2 BA.4/5 COVID-19 Vaccine With Influenza Vaccine

Importance

No data comparing the estimated effectiveness of coadministering COVID-19 vaccines with seasonal influenza vaccine (SIV) in the community setting exist.

Objective

To examine the comparative effectiveness associated with coadministering the BNT162b2 BA.4/5 bivalent mRNA COVID-19 vaccine (BNT162b2-biv [Pfizer BioNTech]) and SIV vs giving each vaccine alone.

Design, Setting, and Participants

A retrospective comparative effectiveness study evaluated US adults aged 18 years or older enrolled in commercial health insurance or Medicare Advantage plans and vaccinated with BNT162b2-biv only, SIV only, or both on the same day between August 31, 2022, and January 30, 2023. Individuals with monovalent or another brand of mRNA bivalent COVID-19 vaccine were excluded.

Exposure

Same-day coadministration of BNT162b2-biv and SIV; receipt of BNT162b2-biv only (for COVID-19-related outcomes) or SIV only (for influenza-related outcomes) were the comparator groups. For adults aged 65 years or older, only enhanced SIVs were included.

Main Outcomes and Measures

COVID-19-related and influenza-related hospitalization, emergency department (ED) or urgent care (UC) encounters, and outpatient visits.

Results

Overall, 3 442 996 individuals (57.0% female; mean [SD] age, 65 [16.7] years) were included. A total of 627 735 individuals had BNT162b2-biv and SIV vaccine coadministered, 369 423 had BNT162b2-biv alone, and 2 445 838 had SIV alone. Among those aged 65 years or older (n = 2 210 493; mean [SD] age, 75 [6.7] years; 57.9% female), the coadministration group had a similar incidence of COVID-19-related hospitalization (adjusted hazard ratio [AHR], 1.04; 95% CI, 0.87-1.24) and slightly higher incidence of emergency department or urgent care encounters (AHR, 1.12; 95% CI, 1.02-1.23) and outpatient visits (AHR, 1.06; 95% CI, 1.01-1.11) compared with the BNT162b2-biv-only group. Among individuals aged 18 to 64 years (n = 1 232 503; mean [SD] age, 47 [13.1] years; 55.4% female), the incidence of COVID-19-related outcomes was slightly higher among those who received both vaccines vs BNT162b2-biv alone (AHR point estimate range, 1.14-1.57); however, fewer events overall in this age group resulted in wider CIs. Overall, compared with those who received SIV alone, the coadministration group had a slightly lower incidence of most influenza-related end points (AHR point estimates 0.83-0.93 for those aged ≥65 years vs 0.76-1.08 for those aged 18-64 years). Negative control outcomes suggested residual bias and calibration of COVID-19-related and influenza-related outcomes with negative controls moved all estimates closer to the null, with most CIs crossing 1.00.

Conclusions and Relevance

In this study, coadministration of BNT162b2-biv and SIV was associated with generally similar effectiveness in the community setting against COVID-19-related and SIV-related outcomes compared with giving each vaccine alone and may help improve uptake of both vaccines.

Recommendations for Prevention and Control of Influenza in Children, 2023-2024

This technical report accompanies the recommendations of the American Academy of Pediatrics for the routine use of influenza vaccine and antiviral medications in the prevention and treatment of influenza in children during the 2023-2024 season. The rationale for the American Academy of Pediatrics recommendation for annual influenza vaccination of all children without medical contraindications starting at 6 months of age is provided. Influenza vaccination is an important strategy for protecting children and the broader community against influenza. This technical report summarizes recent influenza seasons, morbidity and mortality in children, vaccine effectiveness, and vaccination coverage, and provides detailed guidance on vaccine storage, administration, and implementation. The report also provides a brief background on inactivated and live-attenuated influenza vaccines, available vaccines this season, vaccination during pregnancy and breastfeeding, diagnostic testing for influenza, and antiviral medications for treatment and chemoprophylaxis. Strategies to promote vaccine uptake are emphasized.

Examining Public Messaging on Influenza Vaccine over Social Media: Unsupervised Deep Learning of 235,261 Twitter Posts from 2017 to 2023

Although influenza vaccines are safe and efficacious, vaccination rates have remained low globally. Today, with the advent of new media, many individuals turn to social media for personal health questions and information. However, misinformation may be rife, and health communications may be suboptimal. This study, therefore, aimed to investigate the public messaging related to influenza vaccines by organizations over Twitter, which may have a far-reaching influence. The theoretical framework of the COM-B (capacity, opportunity, and motivation component of behavior) model was used to interpret the findings to aid the design of messaging strategies. Employing search terms such as "flu jab", "flu vaccine", "influenza vaccine", and '" influenza jab", tweets posted in English and by organizations from 1 January 2017 to 1 March 2023 were extracted and analyzed. Using topic modeling, a total of 235,261 tweets by organizations over Twitter were grouped into four main topics: publicizing campaigns to encourage influenza vaccination, public education on the safety of influenza vaccine during pregnancy, public education on the appropriate age to receive influenza vaccine, and public education on the importance of influenza vaccine during pregnancy. Although there were no glaring pieces of misinformation or misconceptions, the current public messaging covered a rather limited scope. Further information could be provided about influenza and the benefits of vaccination (capability), promoting community, pharmacist-led influenza vaccination, and other avenues (opportunity), and providing greater incentivization and support for vaccination (motivation).

Three-year COVID-19 and flu vaccinations among medical residents in a tertiary hospital in Italy: The threat of acceptance decline in seasonal campaigns

The COVID-19 vaccination campaign in Italy started in December 2020, and, due to the Omicron variant's emergence, a second booster dose was recommended for high-risk individuals and healthcare workers from July 2022. The aim of the study was to evaluate the vaccination coverages for the COVID-19 second booster dose and to identify predictors of its acceptance within the population of medical residents (MRs) of the Fondazione Policlinico Universitario "A. Gemelli" IRCCS (FPG) University Hospital. The study was conducted at FPG from October 4th to December 21st, 2022, and COVID-19 second booster dose and influenza vaccines were administered. The study analyzed collected data and conducted multivariate logistic regressions to explore potential predictors of vaccination adherence. The analyses performed were compared with the sample enrolled in FPG residency programs at the start of the COVID-19 vaccination campaign. 1968 MRs were involved in the 2022-2023 vaccination campaign (mean age 28.97, SD 3.44), and the second booster dose of COVID-19 vaccination coverage was low (18.80%). Almost all participants opted for co-administration of COVID-19 and influenza vaccinations, leading to a similar rate of influenza vaccination coverage (16.26%). Being a frontline resident, meaning a direct involvement in managing COVID-19 patients and vaccination campaigns, was the main predictor of vaccination adherence (OR 1.72, 95% CI 1.25-2.17). The dropping in influenza vaccination coverage in 2022-2023 and the low adherence to COVID-19 second booster dose among young physicians is concerning, calling for tailored vaccination campaigns and interventions.

Immune interference in effectiveness of influenza and COVID-19 vaccination

Vaccines are known to function as the most effective interventional therapeutics for controlling infectious diseases, including polio, smallpox, rabies, tuberculosis, influenza and SARS-CoV-2. Smallpox has been eliminated completely and polio is almost extinct because of vaccines. Rabies vaccines and Bacille Calmette-Guérin (BCG) vaccines could effectively protect humans against respective infections. However, both influenza vaccines and COVID-19 vaccines are unable to eliminate these two infectious diseases of their highly variable antigenic sites in viral proteins. Vaccine effectiveness (VE) could be negatively influenced (i.e., interfered with) by immune imprinting of previous infections or vaccinations, and repeated vaccinations could interfere with VE against infections due to mismatch between vaccine strains and endemic viral strains. Moreover, VE could also be interfered with when more than one kind of vaccine is administrated concomitantly (i.e., co-administrated), suggesting that the VE could be modulated by the vaccine-induced immunity. In this review, we revisit the evidence that support the interfered VE result from immune imprinting or repeated vaccinations in influenza and COVID-19 vaccine, and the interference in co-administration of these two types of vaccines is also discussed. Regarding the development of next-generation COVID-19 vaccines, the researchers should focus on the induction of cross-reactive T-cell responses and naive B-cell responses to overcome negative effects from the immune system itself. The strategy of co-administrating influenza and COVID-19 vaccine needs to be considered more carefully and more clinical data is needed to verify this strategy to be safe and immunogenic.

Impact of COVID-19 on the Health-Related Quality of Life of Patients during Infection and after Recovery in Saudi Arabia

This study evaluated the impact of COVID-19 and other factors on the health-related quality of life (HRQoL) of Saudi patients during infection and after recovery using the EQ-5D-5L and EQ-VAS instruments. An observational prospective study was conducted in November 2022, during which 389 COVID-19 patients were surveyed during their visit to a medical center. Two weeks after their recovery, they were contacted again to re-evaluate their HRQoL (192 patients either refused to participate or withdrew). The mean of the EQ-5D-5L index and EQ-VAS scores significantly increased from (0.69 ± 0.29 and 63.16 ± 24.9) during infection to (0.92 ± 0.14 and 86.96 ± 15.3) after recovery. Specifically, COVID-19 patients experienced improvement of several HRQoL dimensions post recovery, such as better mobility, enhanced self-care, returning to usual activities, less pain/discomfort, and alleviated anxiety/depression. Multiple linear regression analyses showed that having a normal weight, being employed, not being anemic, and previously taking the BCG vaccine were positively associated with a greater change in the HRQoL. An interaction between being asthmatic and taking the influenza vaccine positively predicted a lower change in the HRQoL. Having a normal weight positively predicted a greater change in the perceived health state after recovery. Increasing the consumption of natural supplements (honey and curcuma) did not improve the HRQoL or the perceived health state. Based on these findings, COVID-19 mildly impacted the HRQoL of Saudis with varying effects depending on some socio-demographic/clinical characteristics of the patients.

Association of dual COVID-19 and seasonal influenza vaccination with COVID-19 infection and disease severity

The clinical guideline states that COVID-19 vaccination can be administered concurrently with Influenza (flu) vaccination (dual vaccination). Using data from the 2021 National Health Interview Survey, we conducted descriptive analysis and multivariate logistic regressions to examine the association between dual vaccination status and self-reported COVID-19 infection and severity. Among 21,387 (weighted 185,251,310) U.S. adults, about 22% did not receive either the flu or COVID-19 vaccine, 6.0% received the flu vaccine only, 29.1% received the COVID-19 vaccine only, and 42.5% received both vaccines. In the multivariate analysis, individuals with dual vaccination (OR, 0.65, 95% CI, 0.56-0.75) and COVID-19 vaccine only (OR, 0.71, 95% CI, 0.61-0.82) were significantly less likely to report COVID-19 infection when compared with those unvaccinated. There was no significant difference in self-reported COVID-19 symptom severity by vaccination status. The results suggest that dual vaccination may be an effective strategy to reduce the contagious respiratory disease burden.

Adverse reactions in young children receiving the coronavirus disease 2019 vaccine

BACKGROUND

We sought to investigate the occurrence of adverse reactions in Japanese children aged 6 months to 4 years who received the BNT162b2 coronavirus disease 2019 (COVID-19) vaccine, to examine parental considerations, and to evaluate potential risk factors associated with post-vaccination fever.

METHODS

This cross-sectional survey study targeted 1617 children aged 6 months to 4 years who received their primary doses of BNT162b2 from November 10, 2022, to April 30, 2023, in Okayama Prefecture. We surveyed the occurrence of local and systemic reactions within 1 week after vaccination, and described the incidence proportions of adverse reactions for 515 participants overall and by age group. The study also examined the impact of previous COVID-19 infection and co-administration of the seasonal influenza vaccine on post-vaccination fever. A survey also assessed parents' reasons for vaccinating their children and the sources of information they used.

RESULTS

Adverse reactions were infrequent (5.2%, with fever ≥37.5°C; no cases exceeded 39°C) and did not increase with vaccine doses administered. The risk of post-vaccination fever was not statistically associated with a history of COVID-19-the adjusted risk ratio (aRR) was 0.99, and the 95% confidence interval (CI) was 0.41-2.39-but was associated with co-administration of the seasonal influenza vaccine (aRR 3.24, 95% CI 1.14-9.18). Parental decisions regarding vaccination were influenced by official government guidelines and primary care physicians' opinion.

CONCLUSION

This study provides valuable insight into the safety profile of the BNT162b2 vaccine in Japanese children aged 6 months to 4 years. Further research involving larger cohorts and appropriate control groups is needed.

Combining Influenza and COVID-19 Booster Vaccination Strategy to Improve Vaccination Uptake Necessary for Managing the Health Pandemic: A Systematic Review and Meta-Analysis

Background: The uptake of COVID-19 booster vaccines has been significantly low. Therefore, it is questionable whether combining the COVID-19 booster vaccines with influenza vaccines can increase the population’s interest in taking such vaccines and manage the health pandemic effectively. Methodology: In this systematic review and meta-analysis, a synthesis of the findings and summary of a total of 30 research articles based on the topic, ‘combining influenza and COVID-19 booster vaccination strategy’ was undertaken. The research articles were identified from three databases, namely, PubMed, Cochran Library, and Google Scholar using specific keywords and inclusion criteria. However, research articles that were not peer-reviewed and not published in English were excluded from the systematic review and meta-analysis. The average risk ratio of the intervention group getting a combination of COVID-19 booster and influenza vaccines from the samples of the included studies was 0.78 with regard to a 95% CI. Such risk ratio is based on the null hypothesis of the current study that combining COVID-19 booster and influenza vaccines can increase the uptake of COVID-19 booster vaccines. On the other hand, the heterogeneity between such studies was I2 = 35%, while the statistical significance of their findings occurred at p < 0.05. The average p-value of the included research studies was p = 0.62 with the proportion of studies with significant p-values being 63.33% which is equivalent to 19 out of 30 studies. Therefore, the null hypothesis was not rejected in more than half of the studies. Results: A synthesis of the chosen research articles revealed that when influenza and COVID-19 booster vaccines are combined, there is potential for an increase in the uptake of the latter, mainly because many populations have already been accustomed to taking influenza vaccines on an annual basis. Conclusions: In this way, through such findings, medical health experts can make informed decisions to increase the population’s willingness to receive the COVID-19 booster vaccines.

Parental Seasonal Influenza Vaccine Hesitancy and Associated Factors in Shanghai, China, during the COVID-19 Pandemic: A Cross-Sectional Study

BACKGROUND

Seasonal influenza may overlap with the COVID-19 pandemic, and children are one of the priority populations for influenza vaccination in China, yet vaccine coverage has been low. This study aimed to investigate the extent of parental influenza vaccine hesitancy (IVH) and to explore the associated factors.

METHODS

The study was conducted in Shanghai, China, from 1 June 2022 to 31 July 2022, using an anonymous questionnaire to survey a random sample of parents of children aged six months to 14 years. Binary logistic regression models were used to identify factors associated with IVH.

RESULTS

Of the 5016 parents, 34.05% had IVH. Multivariate analysis showed that after adjustment for non-modifiable markers (i.e., sociodemographic, health status, and past vaccination status), being affected by negative influenza vaccine news and having higher "complacency" were positively associated with parental IVH. Higher knowledge of influenza vaccination, being recommended by healthcare workers (HCWs), people around having a positive attitude toward influenza vaccine and having higher levels of "confidence" and "convenience" were negatively associated with parental IVH.

CONCLUSIONS

In China, public health education aimed at modifying vaccination-related attitudes and beliefs, as well as knowledge and societal influences, could help reduce influenza vaccination hesitancy.