Safety and efficacy of COVID-19 vaccines: A systematic review and meta-analysis of controlled and randomized clinical trials

Tortured confessions? Potentially erroneous statistical inferences may underpin misleading claims of harms in reanalyses of COVID-19 and HPV vaccines

The safety and efficacy of vaccination is a subject contentious in the public mind. Despite overwhelming evidence of their benefits to public health, COVID-19 and human papilloma virus (HPV) vaccines have been the focus of intense concerns. While the original phase III trials and post-market phase IV studies have continued to show their benefits and positive safety profile, some authors have attempted to reassess the original trial data, purporting to showing hidden harms for both COVID-19 and HPV vaccines. It is critical to ascertain why such divergent claims could stem from analysis of the same data, and this work accordingly examines these reports. In both cases, we find that erroneous statistical assumptions and unwarranted inferences are likely to have influenced the conclusions drawn, and identifies choices that would tend to result in spurious findings. This work also examines the wider issues with unregistered posthoc examinations on known trial data without preregistration, and how this may result in data-dredging, the torturing of data until it confesses to non-existent relationships, and how we might prevent against this on vaccine science.

Effective, but Safe? Physiologically Based Pharmacokinetic (PBPK)-Modeling-Based Dosing Study of Molnupiravir for Risk Assessment in Pediatric Subpopulations

Despite the end of COVID-19 pandemic, only intravenous remdesivir was approved for treatment of vulnerable pediatric populations. Molnupiravir is effective against viruses beyond SARS-CoV-2 and is orally administrable without CYP-interaction liabilities but has a burden of potential bone or cartilage toxicity, observed at doses exceeding 500 mg/kg/day in rats. Especially, activity of molnupiravir against viruses, such as Ebola, with high fatality rates and no treatment option warrants the exploration of potentially effective but safe doses for pediatric populations, i.e., neonates (0-27 days), infants (1-12 months), and children in early childhood (1-12 years). The bone and cartilage toxicity risk for these populations based on the preclinical results has not been systematically investigated yet. Using physiologically based pharmacokinetic (PBPK) modeling, we developed adult PBPK models for doses ranging from 50 to 1200 mg with minimal parameter optimization because of incorporation of CES1, a carboxylesterase. Therein, CES1 served as the main driver for conversion of molnupiravir to its active metabolite β-d-N4-hydroxycytidine (NHC). By incorporation of the ontogeny of CES1 for pediatric populations, we successfully developed PBPK models for different doses ranging from 10 to 75 mg/kg. For molnupiravir, efficacy is driven by the area under the curve (AUC). To achieve a similar AUC to that seen in adults, a dose of around 28 mg/kg BID was necessary in all three investigated pediatric subpopulations. This dose exceeded the safe dose observed in dogs and was slightly below the toxicity-associated human equivalent dose in rats. In summary, the pediatric PBPK models suggested that an efficacious dose posed a toxicity risk. These data confirmed the contraindication for children <18 years.

Receiving three doses of inactivated or mRNA COVID-19 vaccines was associated with lower odds of long COVID symptoms among people with a history of SARS-CoV-2 infection in Hong Kong, China: a cross-sectional survey study

High prevalence of long COVID symptoms has emerged as a significant public health concern. This study investigated the associations between three doses of COVID-19 vaccines and the presence of any and ≥3 types of long COVID symptoms among people with a history of SARS-CoV-2 infection in Hong Kong, China. This is a secondary analysis of a cross-sectional online survey among Hong Kong adult residents conducted between June and August 2022. This analysis was based on a sub-sample of 1,542 participants with confirmed SARS-CoV-2 infection during the fifth wave of COVID-19 outbreak in Hong Kong (December 2021 to April 2022). Among the participants, 40.9% and 16.1% self-reported having any and ≥3 types of long COVID symptoms, respectively. After adjusting for significant variables related to sociodemographic characteristics, health conditions and lifestyles, and SARS-CoV-2 infection, receiving at least three doses of COVID-19 vaccines was associated with lower odds of reporting any long COVID symptoms comparing to receiving two doses (adjusted odds ratio [AOR]: 0.69, 95% CI: 0.54, 0.87, P = .002). Three doses of inactivated and mRNA vaccines had similar protective effects against long COVID symptoms. It is important to strengthen the coverage of COVID-19 vaccination booster doses, even in the post-pandemic era.

COVID-19 vaccines: current and future challenges

As of December 2020, around 200 vaccine candidates for Coronavirus Disease 2019 (COVID-19) are being developed. COVID-19 vaccines have been created on a number of platforms and are still being developed. Nucleic acid (DNA, RNA) vaccines, viral vector vaccines, inactivated vaccines, protein subunit vaccines, and live attenuated vaccines are among the COVID-19 vaccine modalities. At this time, at least 52 candidate vaccines are being studied. Spike protein is the primary protein that COVID-19 vaccines are targeting. Therefore, it is critical to determine whether immunizations provide complete or fractional protection, whether this varies with age, whether vaccinated people are protected from reoccurring diseases, and whether they need booster shots if they've already been inoculated. Despite the enormous achievement of bringing several vaccine candidates to market in less than a year, acquiring herd immunity at the national level and much more so at the global level remains a major challenge. Therefore, we gathered information on the mechanism of action of presently available COVID-19 vaccines in this review and essential data on the vaccines' advantages and downsides and their future possibilities.

Bioaerosols and Airborne Transmission in the Dental Clinic

The importance of aerosols (particles suspended in air) produced during dental procedures became more apparent than ever during the COVID-19 pandemic. Concerns over transmission of infection in these aerosols led to unprecedented disruption to dental services across the world, adversely impacting patients' oral health. This article discusses the evidence related to airborne transmission of infectious diseases and the relevance to dentistry. The production of bioaerosols (aerosols carrying biological material) during dental procedures is explored, as well as how the potential risks posed by these bioaerosols can be controlled. A better understanding of dental bioaerosols is needed to prevent similar disruption to dental services in future outbreaks, and to reduce the risk of infection of dental professionals when treating patients with active infections who require urgent or emergency dental care.

Recent Advances in Designing Adeno-Associated Virus-Based Vaccines Against Viral Infections

Over 80% of the world's deadliest pandemics are caused by viral infections, and vaccination remains the most effective way to prevent these infections from spreading. Since the discovery of the first vaccine over two centuries ago, several vaccine design technologies have been developed. Next-generation vaccines, based on mRNA and viral vector technologies, have recently emerged as alternatives to traditional vaccines. Adenoviral vector-based vaccines against coronavirus disease 2019 have demonstrated a more sustained antibody response as compared to mRNA vaccines. However, this has not been without complications, with a few cases of severe adverse events identified in vaccinated individuals, and the underlying mechanism is the subject of intense investigation. Adeno-associated viral vectors induce a weaker cellular immune response compared to adenoviral vectors, and it is mainly for this reason that there has been a diminished interest in exploring them as a vaccine platform until recently. This review will discuss recent developments and the potential of adeno-associated viral vectors as anti-viral vaccines.

Aplastic Anemia in the light of the COVID-19 pandemic: infection, vaccination, and pathophysiologic mechanisms

Patients infected with SARS-CoV-2 and vaccinated against COVID-19 could develop aplastic anemia (AA). Comprehensive review and analysis were conducted through a selective literature search in PubMed, Scopus, EMBASE, and Web of Science. For this analysis, 26 studies were included, comprising 16 case reports, 7 case series, and 3 observational studies, totaling 53 patients. The causes of acquired or idiopathic AA are diverse; this review presents recent findings, including possible new etiologies such as SARS-CoV-2 infection and COVID-19 vaccines. This possible association is explored, addressing the existing gap, and aiming to improve daily medical practice. This article reviews the relationship between AA and SARS-CoV-2 infection, as well as COVID-19 vaccines, analyzing cases of de novo occurrence and relapses of AA. Although a definitive mechanistic link has not yet been established, possible underlying pathophysiological mechanisms are explored.

In Silico Design of miniACE2 Decoys with In Vitro Enhanced Neutralization Activity against SARS-CoV-2, Encompassing Omicron Subvariants

The COVID-19 pandemic has overwhelmed healthcare systems and triggered global economic downturns. While vaccines have reduced the lethality rate of SARS-CoV-2 to 0.9% as of October 2024, the continuous evolution of variants remains a significant public health challenge. Next-generation medical therapies offer hope in addressing this threat, especially for immunocompromised individuals who experience prolonged infections and severe illnesses, contributing to viral evolution. These cases increase the risk of new variants emerging. This study explores miniACE2 decoys as a novel strategy to counteract SARS-CoV-2 variants. Using in silico design and molecular dynamics, blocking proteins (BPs) were developed with stronger binding affinity for the receptor-binding domain of multiple variants than naturally soluble human ACE2. The BPs were expressed in E. coli and tested in vitro, showing promising neutralizing effects. Notably, miniACE2 BP9 exhibited an average IC50 of 4.9 µg/mL across several variants, including the Wuhan strain, Mu, Omicron BA.1, and BA.2 This low IC50 demonstrates the potent neutralizing ability of BP9, indicating its efficacy at low concentrations.Based on these findings, BP9 has emerged as a promising therapeutic candidate for combating SARS-CoV-2 and its evolving variants, thereby positioning it as a potential emergency biopharmaceutical.

COVID-19 Vaccination and Vaccine Hesitancy in the Gaza Strip from a Cross-Sectional Survey in 2023: Prevalence, Risk Factors, and Associations with Health System Interventions

BACKGROUND

Preventing COVID-19 in Gaza is crucial due to the devastation of advanced health services infrastructure by war. Despite the high protection offered by COVID-19 vaccines against severe disease, a 2021 survey in Gaza found only half of the population was vaccinated, and one-third was vaccine-hesitant. This follow-up study conducted in March 2023 aimed to re-evaluate vaccination levels, hesitancy, exposure to vaccine promotion efforts, and other risk factors in Gaza.

METHODS

A community-based cross-sectional survey with multistage stratified sampling was used. Associations of primary exposures and other determinants with vaccine status and hesitancy were quantified using bivariate and multivariable logistic regression.

RESULTS

In 2023, 63.5% of adults received at least one vaccine dose compared to 49.1% in 2021 (p < 0.001). Vaccine hesitancy prevalence was 31.7% in 2023 versus 34.1% in 2021 (p = 0.395). Adjusted odds of vaccination were 4.2 times higher among those referred by health workers compared to those not referred. Adjusted odds of vaccine hesitancy among those who received information on the vaccine from health workers were 0.3 times that of people who did not receive information.

CONCLUSIONS

Results suggest health workers could play a crucial role in future vaccination strategies, as their vaccine promotion efforts were linked to better vaccine outcomes. Investing in the skills development of community health workers to contribute to these efforts is recommended.

Prevalence of menstrual alterations following COVID-19 vaccination: systematic review & meta-analysis

BACKGROUND

COVID-19 vaccines can lead to diverse local and systemic side effects, but there is limited evidence concerning their association with menstrual cycle changes. This study aimed to assess the prevalence of menstrual cycle alterations after COVID-19 vaccination among adult women.

METHODS

We systematically searched the PubMed, Web of Science and Science Direct databases for observational studies that included adult women and investigated the range of menstrual alterations. The quality of the studies was evaluated via the Newcastle-Ottawa scale. All the data were analyzed via Comprehensive Meta-Analysis Software Version 4.0. Forest plots were created to calculate the individual and pooled prevalence rates of different types of menstrual changes and 95% confidence intervals (CI) via fixed-effects and random-effects models, as appropriate. Heterogeneity was assessed with Q statistics and the I2 test.

RESULTS

Eleven studies, encompassing 26,283 adult women, met our eligibility criteria. Among the selected studies, five were cohort studies, five were cross-sectional studies, and one employed a case‒control design. The menstrual changes included abnormal cycle duration, dysmenorrhea, irregular cycles, and abnormal cycle flow (heavy and light flow), with pooled percentages of 27.3% (CI: 7.2-64.6%), 22% (CI: 5.2-59.4%), 16% (CI: 5.8-37.2%), 11.7% (CI: 5.8-22%), and 5.5% (CI: 2.3-12.5%), respectively.

CONCLUSIONS

This review highlights the prevalence of menstrual changes after COVID-19 vaccination and emphasizes the importance of considering menstrual health as an integral part of postvaccination monitoring and health care interventions. However, longitudinal studies are essential for establishing a definitive causal relationship between COVID-19 vaccination and menstrual alterations.

Prioritization of Vaccines for Introduction in the National Immunization Program in the Republic of Korea

This study presents a framework for determining the prioritization of vaccine introduction in the National Immunization Program (NIP) of the Republic of Korea, with a focus on case examples assessed in 2021 and 2023. We describe the predefined criteria for evaluating the prioritization of vaccines in the NIP and the established process in the Republic of Korea. These criteria included disease characteristics, vaccine characteristics, rationality and efficiency of resource allocation, and the acceptance of immunization. The process of prioritizing NIP introduction involved several sequential steps: a demand survey, evidence collection, preliminary evaluation, priority evaluation, and decision making. In 2021 and 2023, 14 and 25 committee members participated in evaluating the prioritization of vaccines in the NIP, respectively. Overall, 13 and 19 NIP vaccine candidates were included in the 2021 and 2023 evaluations, respectively. Through the Delphi survey and consensus processes, the priority order was determined: vaccination against Rotavirus infection was the top priority in 2021, while Influenza 4v (for chronic disease patients) took precedence in 2023. This study demonstrates an evidence-based decision-making process within the healthcare field. The outlined approach may provide valuable guidance for policymakers in other countries seeking to prioritize the inclusion of new vaccines in their NIP.

COVID-19 Vaccination and Public Health: Addressing Global, Regional, and Within-Country Inequalities

The COVID-19 pandemic, with over 775 million cases and 7 million deaths by May 2024, has drastically impacted global public health and exacerbated existing healthcare inequalities. The swift development and distribution of COVID-19 vaccines have been critical in combating the virus, yet disparities in access to and administration of the vaccine have highlighted deep-seated inequities at global, regional, and national levels. Wealthier nations have benefited from early access to vaccines, while low- and middle-income countries (LMICs) have faced persistent shortages. Initiatives such as COVAX aimed to address these disparities, but challenges persist. Socioeconomic factors, education, ethnic identity, and the healthcare infrastructure play crucial roles in vaccine equity. For example, lower-income individuals often face barriers such as poor access to healthcare, misinformation, and logistical challenges, particularly in rural areas. Addressing these inequities requires a multifaceted approach, integrating national policies with local strategies to enhance vaccines' accessibility, counter misinformation, and ensure equitable distribution. Collaborative efforts at all levels are essential to promote vaccine equity and effectively control the pandemic, ensuring that all populations have fair access to life-saving vaccines. This review explores these complex issues, offering insights into the barriers and facilitators of vaccine equity and providing recommendations to promote more equitable and effective vaccination programs. With a focus on the different levels at which vaccination policies are planned and implemented, the text provides guidelines to steer vaccination strategies, emphasizing the role of international cooperation and local policy frameworks as keys to achieving equitable vaccination coverage.

In vitro antibody-mediated SARS-CoV-2 infection suppression through human ACE2 receptor blockade

Vaccines and antibodies that specifically target or neutralize components of the SARS-CoV-2 virus are effective in prevention and treatment of human patients with SARS-CoV-2 infection. However, vaccines and SARS-CoV-2 neutralization antibodies target a subset of epitopes of viral proteins, and the fast evolution of the SARS-CoV-2 virus and the continuing emergence of SARS-CoV-2 variants confer SARS-CoV-2 immune escape from these therapies. ACE2 is the human cell receptor that serves as the entry point for SARS-CoV-2 into human cells and thus is the gatekeeper for SARS-CoV-2 infection of humans. We report here the development of 4G8C11, an anti-human ACE2 receptor monoclonal antibody that recognizes ACE2 on human cell surfaces. We determined that 4G8C11 blocks SARS-CoV-2 and variant infection of ACE2+ human cells. Furthermore, 4G8C11 has minimal effects on ACE2 receptor activity. 4G8C11 is therefore a monoclonal antibody for ACE2 receptor detection and potentially an effective immunotherapeutic agent for SARS-CoV-2 and variants.

Vaccines and monoclonal antibodies: new tools for malaria control

SUMMARYMalaria remains one of the biggest health problems in the world. While significant reductions in malaria morbidity and mortality had been achieved from 2000 to 2015, the favorable trend has stalled, rather significant increases in malaria cases are seen in multiple areas. In 2022, there were 249 million estimated cases, and 608,000 malaria-related deaths, mostly in infants and children aged under 5 years, globally. Therefore, in addition to the expansion of existing anti-malarial control measures, it is critical to develop new tools, such as vaccines and monoclonal antibodies (mAbs), to fight malaria. In the last 2 years, the first and second malaria vaccines, both targeting Plasmodium falciparum circumsporozoite proteins (PfCSP), have been recommended by the World Health Organization to prevent P. falciparum malaria in children living in moderate to high transmission areas. While the approval of the two malaria vaccines is a considerable milestone in vaccine development, they have much room for improvement in efficacy and durability. In addition to the two approved vaccines, recent clinical trials with mAbs against PfCSP, blood-stage vaccines against P. falciparum or P. vivax, and transmission-blocking vaccine or mAb against P. falciparum have shown promising results. This review summarizes the development of the anti-PfCSP vaccines and mAbs, and recent topics in the blood- and transmission-blocking-stage vaccine candidates and mAbs. We further discuss issues of the current vaccines and the directions for the development of next-generation vaccines.

Predictive factors of coronavirus disease (COVID-19) vaccination series completion: a one-year longitudinal web-based observational study in Japan

Introduction

Addresing vaccine hesitancy is considered an important goal in management of the COVID-19 pandemic. We sought to understand what factors influenced people, especially those initially hesitant, to receive two or more vaccine doses within a year of the vaccine's release.

Methods

We conducted longitudinal Web-based observational studies of 3,870 individuals. The surveys were conducted at four different time points: January 2021, June 2021, September 2021, and December 2021. In the baseline survey (January 2021), we assessed vaccination intention (i.e., "strongly agree" or "agree" [acceptance], "neutral" [not sure], and "disagree" or "strongly disagree" [hesitance]), and assumptions about coronavirus disease (COVID-19), COVID-19 vaccine, COVID-19-related health preventive behavior, and COVID-19 vaccine reliability. In subsequent surveys (December 2021), we assessed vaccination completion (i.e., ≥2 vaccinations). To investigate the relationship between predictors of COVID-19 vaccination completion, a multivariable logistic regression model was applied. Adjusted odds ratios (AORs) and 95% confidence intervals (CIs) were calculated while adjusting for gender, age, marital status, presence of children, household income category, and presence of diseases under treatment. In a stratified analysis, predictors were determined based on vaccination intention.

Results

Approximately 96, 87, and 72% of those who demonstrated acceptance, were not sure, or hesitated had been vaccinated after 1 year, respectively. Overall, significant factors associated with COVID-19 vaccine compliance included the influence of others close to the index participant (social norms) (AOR, 1.80; 95% CI, 1.56-2.08; p < 0.001), vaccine confidence (AOR, 1.39; 95% CI, 1.18-1.64; p < 0.001) and structural constraints (no time, inconvenient location of medical institutions, and other related factors) (AOR, 0.80; 95% CI, 0.70-0.91; p = 0.001). In the group of individuals classified as hesitant, significant factors associated with COVID-19 vaccine compliance included social norms (AOR, 2.43; 95% CI, 1.83-3.22; p < 0.001), confidence (AOR, 1.44; 95% CI, 1.10-1.88; p = 0.008), and knowledge (AOR, 0.69; 95% CI, 0.53-0.88; p = 0.003).

Discussion

We found that dissemination of accurate information about vaccines and a reduction in structural barriers to the extent possible enhanced vaccination rates. Once the need for vaccination becomes widespread, it becomes a social norm, and further improvements in these rates can then be anticipated. Our findings may help enhance vaccine uptake in the future.