Efficacy and safety of an inactivated whole-virion vaccine against COVID-19, QazCovid-in®, in healthy adults: A multicentre, randomised, single-blind, placebo-controlled phase 3 clinical trial with a 6-month follow-up

Transformative approaches in SARS-CoV-2 management: Vaccines, therapeutics and future direction

The global healthcare and economic challenges caused by the pandemic of COVID-19 reinforced the urgent demand for quick and effective therapeutic and preventative interventions. While vaccines served as the frontline of defense, antivirals emerged as adjunctive countermeasures, especially for people who developed infection, were immunocompromised, or were reluctant to be vaccinated. Beyond the serious complications of SARS-CoV-2 infection, the threats of long-COVID and the potential for zoonotic spillover continue to be significant health concerns that cannot be overlooked. Moreover, the incessant viral evolution, clinical safety issues, waning immune responses, and the emergence of drug-resistant variants pinpoint towards more severe viral threats in the future and call for broad-spectrum innovative therapies as a pre-pandemic preparedness measure. The present review provides a comprehensive up-to-date overview of the strategies utilized in the development of classical and next-generation vaccines against SARS-CoV-2, the clinical and experimental data obtained from clinical trials, while addressing safety risks that may arise. Besides vaccines, the review also covers recent breakthroughs in anti-SARS-CoV-2 drug discovery, emphasizing druggable viral and host targets, virus- and host-targeting antivirals, and highlighting mechanistically representative molecules that are either approved or are under clinical investigation. In conclusion, the integration of both vaccines and antiviral therapies, along with swift innovative strategies to address viral evolution and drug resistance is crucial to strengthen our preparedness against future viral outbreaks.

Immunobiology and immunotherapy of COVID-19

The SARS-CoV-2 outbreak in late 2019 triggered a major increase in activities related to immunobiology and immunotherapy to cope with and find solutions to end the COVID-19 pandemic. The unprecedented approach to research and development of drugs and vaccines against SARS-CoV-2 has substantially improved the understanding of immunobiology for COVID-19, which can also be applied to other infectious diseases. Major efforts were dedicated to the repurposing of existing antiviral drugs and the development of novel ones. For this reason, numerous approaches to evaluating interferons, immunoglobulins, and cytokine inhibitors have been conducted. Antibody-based therapies, especially employing monoclonal antibodies have also been on the agenda. Cell-based therapies involving dendritic cells, macrophages, and CAR T-cell approaches have been evaluated. Many existing antiviral drugs have been repurposed for COVID-19 and novel formulations have been tested. The extraordinarily rapid development of efficient vaccines led to the breakthrough of novel vaccine approaches such as mRNA-based vaccines saving millions of lives. Waning immunity of existing vaccines and emerging SARS-CoV-2 variants have required additional booster vaccinations and re-engineering of new versions of COVID-19 vaccines.

Determinants of COVID-19 Vaccine Uptake Among People Living with Human Immunodeficiency Virus

BackgroundHuman immunodeficiency virus (HIV) cases are rising in Central Asia and Kazakhstan. People living with HIV (PLWH) in Kazakhstan are at heightened risk of severe COVID-19. We conducted a study to evaluate determinants of COVID-19 vaccine uptake among PLWH in Kazakhstan.MethodsIn this cross-sectional study, 196 PLWH were recruited from the Almaty City AIDS Center (July 2022-January 2023). We used logistic regression to evaluate how multilevel factors are associated with COVID-19 vaccine uptake among PLWH in Kazakhstan.ResultsCOVID-19 vaccine non-uptake was associated with higher HIV stigma scores (AOR = 1.08, 95%CI:1.02,1.16, P = 0.017), a lower level of education (AOR = 2.53, 95%CI: 1.04,6.17, P = 0.0412), and never receiving the flu vaccine (AOR = 15.64, 95%CI:3.66,66.89, P = 0.0002). Participants with at least mild anxiety symptoms (AOR = 0.15, 95%CI:0.03,0.64, P = 0.0107) and a positive attitude towards vaccination (AOR = 0.79, 95%CI: 0.73,0.86, P < 0.0001) were less likely to remain unvaccinated against COVID-19.ConclusionsCOVID-19 vaccination campaigns should be tailored for PLWH and incorporate stigma reduction interventions within healthcare settings.

Safety, tolerability, and immunogenicity of PIKA-adjuvanted recombinant SARS-CoV-2 spike protein subunit vaccine in healthy adults: an open-label randomized phase I clinical trial

Purpose

This phase I study aimed to assess the safety, tolerability, and immunogenicity of the PIKA-adjuvanted recombinant severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike (S) protein subunit vaccine in healthy adults aged 18 years and older.

Materials and Methods

This is a phase I, open-label, dose-escalation study at three dose levels (5 µg, 10 µg, and 20 µg) of the PIKA coronavirus disease 2019 (COVID-19) vaccine administered intramuscularly. The three vaccine arms are (A) subjects who have never received any COVID-19 vaccination or have had COVID-19 infection for >6 months prior to enrolment; (B1) subjects whose COVID-19 primary vaccination series was completed with an inactivated COVID-19 vaccine; and (B2) subjects whose primary series was completed with messenger RNA COVID-19 vaccine.

Results

Subjects who reported solicited adverse events (AEs) within seven days post-vaccination ranged from 35% to 60% within each vaccine arm. Most solicited AEs were mild local pain and tenderness. Systemic solicited AEs were only reported in Arm A. In all three vaccine arms, neutralizing antibody geometric mean titers were highest at day 28 (Arms B1 and B2) or day 35 (Arm A) than at baseline for all dose levels against the Wuhan (wild original SARS-CoV-2 virus, Wuhan-Hu-1), Delta (B.1.617.2), and Omicron (B.1.1.529) variants. These were sustained at day 183. Seroconversion rates at day 35 (Arm A, 85.7%-92.9%) or day 183 (Arms B1, 90.9%-100.0%, and B2, 18.2%-36.4%) and geometric mean fold rises were highest in the 5-µg dose level against all three variants.

Conclusion

The PIKA-adjuvanted recombinant SARS-CoV-2 S protein subunit vaccine showed promising immunogenicity profile with no safety concerns. A dose-dependent immune response was observed, with slight advantages seen in low-dose (5 µg and 10 µg) groups (ClinicalTrials.gov registration number: NCT05305300).

COVID-19: vaccination, therapeutics and a review of the science and public health

COVID-19, stemming from the SARS-CoV-2 virus, has initiated a worldwide respiratory pandemic. Remarkable headway has been made in the realm of vaccination, as nearly every nation has initiated COVID-19 vaccine deployment. However, a mere 32.6% of individuals in low-income countries have received only a single vaccine dose. Unprecedented research and development endeavors have yielded over 170 COVID-19 vaccines, several of which are now in practical use. These vaccines have demonstrated remarkable efficacy in averting severe illness, hospitalization, and fatalities from COVID-19, even against emerging variants. Research pursuits persist, concentrating on novel vaccine technologies, oral and nasal vaccines, broader coronavirus protection, and vaccine combinations. In the realm of therapeutics, there have been significant strides in developing oral antiviral medications and monoclonal antibodies. Nonetheless, challenges in COVID-19 vaccination persist, encompassing issues of hesitancy, accessibility, financial barriers, knowledge gaps, and logistical hindrances. Robust monitoring via global agencies and reporting systems remains pivotal. Strategies for enhancing vaccination efficacy are rooted in fostering trust, countering misinformation, and expanding access. As for therapeutics, the approach involves dedicated research, clinical trials, regulatory streamlining, stockpiling, and international collaboration. Telemedicine and public awareness campaigns play integral roles in this effort, with coordination being the linchpin for preserving lives and mitigating the disease's impact. The global campaign against COVID-19 has witnessed substantial advancements, with an ongoing research focus on developing vaccines and therapeutics that are not only more accessible and affordable but also more effective, particularly for populations in low-income countries and vulnerable communities.

Immune reactivity of two biological models to vaccination with inactivated vaccine QazVac against coronavirus infection COVID-19

INTRODUCTION

Specific prevention of a number of infectious diseases has been introduced into the vaccination schedule. The production of immunoprophylactic drugs, in order to establish standard properties, including safety and specific effectiveness, requires strict adherence to manufacturing regulations, and the reliability of the results obtained requires monitoring of these parameters. The specific effectiveness of vaccine preparations is standardized according to the indicators of stimulation of specific antibody response formed in the body of vaccinated model biological objects.

OBJECTIVE

Determination of the immune reactivity of white mice to vaccination with the QazVac vaccine to establish the possibility of using them as a biological model in assessing the immunogenicity of the vaccine instead of Syrian hamsters.

MATERIALS AND METHODS

The immune reactivity of model animals was assessed by the seroconversion rate, dynamics of antibody titers to the SARS-CoV-2 virus formed in the body after vaccination with the test vaccine. In the case of seropositivity of animals before administration of vaccine or placebo, the level of immune reactivity was calculated by the difference in antibody titers between control and vaccinated animals or by the difference in antibody titers before and after immunization. Specific antibodies were detected and their titer was determined using a neutralization reaction.

RESULTS

The research results showed that the tested biological models had approximately the same immune reactivity to the administration of the QazVac vaccine, confirmed by the level and dynamics of antibody titers. When analyzing the fold increase in antibody titers in comparison to those of control animals, Syrian hamsters were more reactive compared to mice. But SPF white mice were standardized in their lack of the immune reactivity to SARS-CoV-2 virus before the immunization.

CONCLUSION

The data obtained indicate that the immune reactivity of white mice to the administration of the QazVac vaccine in terms of the rate and dynamics of the formation of virus-neutralizing antibodies is approximately equivalent to the immune reactivity of Syrian hamsters. Before immunization with the vaccine, SPF white mice, in contrast to Syrian hamsters, do not have humoral immunity specific to the SARS-CoV-2 virus. The immune reactivity equivalent to that observed of Syrian hamsters and the absence of antibodies to the SARS-CoV-2 virus at a baseline indicate the superiority of the use of white mice in assessing the immunogenicity of vaccines against COVID-19 and/or obtaining specific factors of humoral immunity.

Autoimmune response after SARS-CoV-2 infection and SARS-CoV-2 vaccines

The complicated relationships between autoimmunity, COVID-19, and COVID-19 vaccinations are described, giving insight into their intricacies. Antinuclear antibodies (ANA), anti-Ro/SSA, rheumatoid factor, lupus anticoagulant, and antibodies against interferon (IFN)-I have all been consistently found in COVID-19 patients, indicating a high prevalence of autoimmune reactions following viral exposure. Furthermore, the discovery of human proteins with structural similarities to SARS-CoV-2 peptides as possible autoantigens highlights the complex interplay between the virus and the immune system in initiating autoimmunity. An updated summary of the current status of COVID-19 vaccines is presented. We present probable pathways underpinning the genesis of COVID-19 autoimmunity, such as bystander activation caused by hyperinflammatory conditions, viral persistence, and the creation of neutrophil extracellular traps. These pathways provide important insights into the development of autoimmune-related symptoms ranging from organ-specific to systemic autoimmune and inflammatory illnesses, demonstrating the wide influence of COVID-19 on the immune system.

Comparative efficacy and safety of COVID-19 vaccines in phase III trials: a network meta-analysis

BACKGROUND

Over a dozen vaccines are in or have completed phase III trials at an unprecedented speed since the World Health Organization (WHO) declared COVID-19 a pandemic. In this review, we aimed to compare and rank these vaccines indirectly in terms of efficacy and safety using a network meta-analysis.

METHODS

We searched Embase, MEDLINE, and the Cochrane Library for phase III randomized controlled trials (RCTs) from their inception to September 30, 2023. Two investigators independently selected articles, extracted data, and assessed the risk of bias. Outcomes included efficacy in preventing symptomatic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and the incidence of serious adverse events (SAEs) according to vaccine type and individual vaccines in adults and elderly individuals. The risk ratio and mean differences were calculated with 95% confidence intervals using a Bayesian network meta-analysis.

RESULTS

A total of 25 RCTs involving 22 vaccines were included in the study. None of vaccines had a higher incidence of SAEs than the placebo. Inactivated virus vaccines might be the safest, with a surface under the cumulative ranking curve (SUCRA) value of 0.16. BIV1-CovIran showed the highest safety index (SUCRA value: 0.13), followed by BBV152, Soberana, Gam-COVID-Vac, and ZF2001. There were no significant differences among the various types of vaccines regarding the efficacy in preventing symptomatic SARS-CoV-2 infection, although there was a trend toward higher efficacy of the mRNA vaccines (SUCRA value: 0.09). BNT162b2 showed the highest efficacy (SUCRA value: 0.02) among the individual vaccines, followed by mRNA-1273, Abdala, Gam-COVID-Vac, and NVX-CoV2373. BNT162b2 had the highest efficacy (SUCRA value: 0.08) in the elderly population, whereas CVnCoV, CoVLP + AS03, and CoronaVac were not significantly different from the placebo.

CONCLUSIONS

None of the different types of vaccines were significantly superior in terms of efficacy, while mRNA vaccines were significantly inferior in safety to other types. BNT162b2 had the highest efficacy in preventing symptomatic SARS-CoV-2 infection in adults and the elderly, whereas BIV1-CovIran had the lowest incidence of SAEs in adults.

COVID-19 Vaccines: Where Did We Stand at the End of 2023?

Vaccine development against SARS-CoV-2 has been highly successful in slowing down the COVID-19 pandemic. A wide spectrum of approaches including vaccines based on whole viruses, protein subunits and peptides, viral vectors, and nucleic acids has been developed in parallel. For all types of COVID-19 vaccines, good safety and efficacy have been obtained in both preclinical animal studies and in clinical trials in humans. Moreover, emergency use authorization has been granted for the major types of COVID-19 vaccines. Although high safety has been demonstrated, rare cases of severe adverse events have been detected after global mass vaccinations. Emerging SARS-CoV-2 variants possessing enhanced infectivity have affected vaccine protection efficacy requiring re-design and re-engineering of novel COVID-19 vaccine candidates. Furthermore, insight is given into preparedness against emerging SARS-CoV-2 variants.

Effect of homologous or heterologous vaccine booster over two initial doses of inactivated COVID-19 vaccine

INTRODUCTION

Inactivated vaccines were delivered to low- and middle-income countries during the early pandemics of COVID-19. Currently, more than 10 inactivated COVID-19 vaccines have been developed. Most inactivated vaccines contain an inactivated whole-cell index SARS-CoV-2 strain that is adjuvant. Whole virions inactivated with aluminum hydroxide vaccines were among the most commonly used. However, with the emerging of COVID-19 variants and waning of the immunity of two doses of after 3 months, WHO and many local governments have recommended the booster-dose program especially with heterologous platform vaccine.

AREA COVERED

This review was conducted through a literature search of the MEDLINE database to identify articles published from 2020 to 2023 covered the inactivated COVID-19 vaccines primary series with homologous and heterologous booster focusing on safety, immunogenicity, efficacy, and effectiveness.

EXPERT OPINION

The inactivated vaccines, especially whole virion inactivated in aluminum hydroxide appeared to be safe and had good priming effects. Immune responses generated after one dose of heterologous boost were high and able to preventing severity of disease and symptomatic infection. A new approach to inactivated vaccine has been developed using inactivating recombinant vector virus-NDV-HXP-S vaccine.

Comparing the Efficacy and Adverse Events of Available COVID-19 Vaccines Through Randomized Controlled Trials: Updated Systematic Review and Network Meta-analysis

BACKGROUND

Different vaccines have so far been developed and approved to cope with COVID-19 in the world. The aim of this updated network meta-analysis (NMA) was to compare and rank all available vaccines in terms of efficacy and complications simultaneously. Study Design: A systematic review.

METHODS

Three major international databases, including Web of Science, Medline via PubMed, and Scopus, were searched through September 2023. The transitivity assumption was evaluated qualitatively in terms of epidemiologic effect modifiers. The exposure of interest in this study was receiving any available COVID-19 vaccine, and the primary outcome of interest was the incidence of symptomatic COVID-19. In this NMA, the relative risk of symptomatic COVID-19 was used to summarize the efficacy of vaccines in preventing COVID-19. The data were analyzed using the frequentist-based approach, and the results were reported using a random-effects model. Finally, the vaccines were ranked using a P-score.

RESULTS

In total, 34 randomized controlled trials (RCTs) met the eligibility criteria for this systematic review and NMA out of 3682 retrieved references. Based on the results of the NMA, mRNA-1273 was the most effective vaccine in preventing COVID-19 and demonstrated the highest P-score (0.93). The relative risk (RR) for mRNA-1273 versus placebo was 0.07 (95% confidence interval [CI]: 0.03, 0.17). The second and third-ranked vaccines were BNT-162b2 (RR=0.08; 95% CI: 0.04, 0.15; P-score=0.93) and Gam-COVID-Vac (0.09; 95% CI: 0.03, 0.25; 0.88).

CONCLUSION

Based on the results of this NMA, it seems that all available vaccines were effective in COVID-19 prevention. However, the top three ranked vaccines were mRNA-1273, BNT-162b2, and Gam-COVID-Vac, respectively.

Immunogenicity and safety of adjuvant-associated COVID-19 vaccines: A systematic review and meta-analysis of randomized controlled trials

Background

The benefits and risks of adjuvant-associated COVID-19 vaccines (ACVs) are unclear. The study aimed to assess the immunogenicity and safety of ACVs compared with controls (placebo or the same vaccine without adjuvants [NACVs]).

Methods

Randomized controlled trials sourced from PubMed, EMBASE, Web of Science, and Cochrane Library were systematically reviewed. Evaluators extracted information independently. The evidence quality was assessed using random-effects models. The risk of bias was assessed using the Cochrane Risk of Bias tool.

Results

Of the 33 studies, 27 analyzed immunogenicity (n = 9069, ACVs group; n = 3757, control), and 26 analyzed safety (n = 58669, ACVs groups; n = 30733 control). Compared with controls, full vaccination with ACVs produced significant immune responses (relative risk [RR] of seroneutralization reaction, 12.3; 95 % confidence interval [95 % CI], 6.92-21.89; standardized mean deviation of geometric mean titer 3.96, 95 % CI, 3.35-4.58). Additionally, ACVs produced significant immunoreactivity compared with NACVs only (P < 0.05). Furthermore, full vaccination with ACVs significantly increased the risk of local and systemic adverse reactions (AEs) compared with controls. However, vaccination with ACVs did not significantly increase the risk of systemic and localized AEs compared with vaccination with NACVs only (P > 0.05). It was observed that ACVs had a lower risk of all-cause mortality than controls (RR, 0.51; 95 % CI 0.30-0.87). It was further found that ACVs produced nAb response against all sublines of the Omicron variant, but the antibody titers were lower than those for the SARS-CoV-2 original strain.

Conclusions

The findings of this meta-analysis demonstrate that ACVs may have a superior effect and an acceptable safety in preventing COVID-19. Although these results suggest the potential of ACVs, further studies are required.

Pre-Clinical Safety and Immunogenicity Study of a Coronavirus Protein-Based Subunit Vaccine for COVID-19

Creating an effective and safe vaccine is critical to fighting the coronavirus infection successfully. Several types of COVID-19 vaccines exist, including inactivated, live attenuated, recombinant, synthetic peptide, virus-like particle-based, DNA and mRNA-based, and sub-unit vaccines containing purified immunogenic viral proteins. However, the scale and speed at which COVID-19 is spreading demonstrate a global public demand for an effective prophylaxis that must be supplied more. The developed products promise a bright future for SARS-CoV-2 prevention; however, evidence of safety and immunogenicity is mandatory before any vaccine can be produced. In this paper, we report on the results of our work examining the safety, toxicity, immunizing dose choice, and immunogenicity of QazCoVac-P, a Kazakhstan-made sub-unit vaccine for COVID-19. First, we looked into the product's safety profile by assessing its pyrogenicity in vaccinated rabbit models and using the LAL (limulus amebocyte lysate) test. We examined the vaccine's acute and sub-chronic toxicity on BALB/c mice and rats. The vaccine did not cause clinically significant toxicity-related changes or symptoms in our toxicity experiments. Finally, we performed a double immunization of mice, ferrets, Syrian hamsters, and rhesus macaques (Macaca mulatta). We used ELISA to measure antibody titers with the maximum mean geometric titer of antibodies in the animals' blood sera totaling approximately 8 log2. The results of this and other studies warrant recommending the QazCoVac-P vaccine for clinical trials.

COVID-19 Incidence Proportion as a Function of Regional Testing Strategy, Vaccination Coverage, and Vaccine Type

Introduction: The COVID-19 pandemic has become a serious challenge for humanity almost everywhere globally. Despite active vaccination around the world, the incidence proportion in different countries varies significantly as of May 2022. The reason may be a combination of demographic, immunological, and epidemiological factors. The purpose of this study was to analyze possible relationships between COVID-19 incidence proportion in the population and the types of SARS-CoV-2 vaccines used in different countries globally, taking into account demographic and epidemiological factors. Materials and methods: An initial database was created of demographic and immunoepidemiological information about the COVID-19 situation in 104 countries collected from published official sources and repository data. The baseline included, for each country, population size and density; SARS-CoV-2 testing coverage; vaccination coverage; incidence proportion; and a list of vaccines that were used, including their relative share among all vaccinations. Subsequently, the initial data set was stratified by population and vaccination coverage. The final data set was subjected to statistical processing both in general and taking into account population testing coverage. Results: After formation of the final data set (including 53 countries), it turned out that reported COVID-19 case numbers correlated most strongly with testing coverage and the proportions of vaccine types used, specifically, mRNA (V1); vector (V2); peptide/protein (V3); and whole-virion/inactivated (V4). Due to the fact that an inverse correlation was found between 'reported COVID-19 case numbers' with V2, V3, and V4, these three vaccine types were also combined into one analytic group, 'non-mRNA group' vaccines (Vnmg). When the relationship between vaccine type and incidence proportion was examined, minimum incidence proportion was noted at V1:Vnmg ratios (%:%) from 0:100 to 30:70. Maximum incidence proportion was seen with V1:Vnmg from 80:20 to 100:0. On the other hand, we have shown that the number of reported COVID-19 cases in different countries largely depends on testing coverage. To offset this factor, countries with low and extremely high levels of testing were excluded from the data set; it was then confirmed that the largest number of reported COVID-19 cases occurred in countries with a dominance of V1 vaccines. The fewest reported cases were seen in countries with a dominance of Vnmg vaccines. Conclusion: In this paper, we have shown for the first time that the level of reported COVID-19 incidence proportion depends not only on SARS-CoV-2 testing and vaccination coverage, which is quite logical, but probably also on the vaccine types used. With the same vaccination level and testing coverage, those countries that predominantly use vector and whole-virion vaccines feature incidence proportion that is significantly lower than countries that predominantly use mRNA vaccines.

Factors associated with COVID-19 vaccine confidence among primary care providers in Kazakhstan, March-April 2021

Introduction

Vaccination is a critical public health intervention, and vaccine hesitancy is a major threat. Globally, confidence in COVID-19 vaccines has been low, and rates of routine immunizations decreased during the COVID-19 pandemic. Because healthcare providers are a trusted source of information on vaccination in Kazakhstan, it was vital to understand their knowledge, attitudes and practices (KAP) related to both routine and COVID-19 vaccines.

Methods

From March to April 2021, we conducted a cross-sectional study among the healthcare providers responsible for vaccination in 54 primary care facilities in three cities in Kazakhstan. All consenting providers anonymously completed structured online questionnaires at their place of work. A provider was classified as having COVID-19 vaccine confidence if they planned to get a COVID-19 vaccine, believed that COVID-19 vaccines are important to protect their community and either believed the vaccine was important to protect themselves or believed that getting a vaccine was safer than getting COVID-19. Statistical analysis included chi-square, Spearman's rank correlation coefficient, and Poisson regression.

Results

Of 1,461 providers, 30% had COVID-19 vaccine confidence, 40% did not, and 30% would refuse vaccination. Participants were mostly female (92%) and ≤ 35 years old (57%). Additionally, 65% were nurses, 25% were family physicians, and 10% were pediatricians. Adequate KAP for routine vaccines was low (22, 17, and 32%, respectively). Adequate knowledge was highest among pediatricians (42%) and family physicians (28%) and lowest among nurses (17%). Misconceptions about vaccines were high; 54% believed that influenza vaccines cause flu, and 57% believed that there is a scientifically proven association between vaccination and autism and multiple sclerosis. About half (45%) of the practitioners felt confident answering patient vaccine-related concerns. In adjusted models, COVID-19 vaccine confidence was positively associated with adequate knowledge of vaccines (prevalence ratio: 1.2, 95% confidence interval: 1.0-1.4) and adequate attitudes related to routine vaccines (3.1, 2.7-3.6).

Conclusion

Our study uncovers critical areas for interventions to improve KAP related to routine immunizations and COVID-19 vaccine confidence among providers in Kazakhstan. The complex relationship between KAP of routine vaccines and COVID-19 vaccine confidence underscores the importance of addressing vaccine hesitancy more broadly and not focusing solely on COVID-19.

COVID-19: An Overview of SARS-CoV-2 Variants-The Current Vaccines and Drug Development

The world is presently in crisis facing an outbreak of a health-threatening microorganism known as COVID-19, responsible for causing uncommon viral pneumonia in humans. The virus was first reported in Wuhan, China, in early December 2019, and it quickly became a global concern due to the pandemic. Challenges in this regard have been compounded by the emergence of several variants such as B.1.1.7, B.1.351, P1, and B.1.617, which show an increase in transmission power and resistance to therapies and vaccines. Ongoing researches are focused on developing and manufacturing standard treatment strategies and effective vaccines to control the pandemic. Despite developing several vaccines such as Pfizer/BioNTech and Moderna approved by the U.S. Food and Drug Administration (FDA) and other vaccines in phase 4 clinical trials, preventive measures are mandatory to control the COVID-19 pandemic. In this review, based on the latest findings, we will discuss different types of drugs as therapeutic options and confirmed or developing vaccine candidates against SARS-CoV-2. We also discuss in detail the challenges posed by the variants and their effect on therapeutic and preventive interventions.

COVID-19 Vaccines over Three Years after the Outbreak of the COVID-19 Epidemic

The outbreak of COVID-19 started in December 2019 and spread rapidly all over the world. It became clear that the development of an effective vaccine was the only way to stop the pandemic. It was the first time in the history of infectious diseases that the process of the development of a new vaccine was conducted on such a large scale and accelerated so rapidly. At the end of 2020, the first COVID-19 vaccines were approved for marketing. At the end of March 2023, over three years after the outbreak of the COVID-19 pandemic, 199 vaccines were in pre-clinical development and 183 in clinical development. The candidate vaccines in the clinical phase are based on the following platforms: protein subunit, DNA, RNA, non-replication viral vector, replicating viral vector, inactivated virus, virus-like particles, live attenuated virus, replicating viral vector combined with an antigen-presenting cell, non-replication viral vector combined with an antigen-presenting cell, and bacterial antigen-spore expression vector. Some of the new vaccine platforms have been approved for the first time for human application. This review presents COVID-19 vaccines currently available in the world, procedures for assurance of the quality and safety of the vaccines, the vaccinated population, as well as future perspectives for the new vaccine platforms in drug and therapy development for infectious and non-infectious diseases.

T-cell immunity to SARS-CoV-2: what if the known best is not the optimal course for the long run? Adapting to evolving targets

Humanity did surprisingly well so far, considering how unprepared it was to respond to the coronavirus disease 2019 (COVID-19) threat. By blending old and ingenious new technology in the context of the accumulated knowledge on other human coronaviruses, several vaccine candidates were produced and tested in clinical trials in record time. Today, five vaccines account for the bulk of the more than 13 billion doses administered worldwide. The ability to elicit biding and neutralizing antibodies most often against the spike protein is a major component of the protection conferred by immunization but alone it is not enough to limit virus transmission. Thus, the surge in numbers of infected individuals by newer variants of concern (VOCs) was not accompanied by a proportional increase in severe disease and death rate. This is likely due to antiviral T-cell responses, whose evasion is more difficult to achieve. The present review helps navigating the very large literature on T cell immunity induced by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and vaccination. We examine the successes and shortcomings of the vaccinal protection in the light of the emergence of VOCs with breakthrough potential. SARS-CoV-2 and human beings will likely coexist for a long while: it will be necessary to update existing vaccines to improve T-cell responses and attain better protection against COVID-19.

Effectiveness of four vaccines in preventing SARS-CoV-2 infection in Almaty, Kazakhstan in 2021: retrospective population-based cohort study

Background

In February 2021 Kazakhstan began offering COVID-19 vaccines to adults. Breakthrough SARS-CoV-2 infections raised concerns about real-world vaccine effectiveness. We aimed to evaluate effectiveness of four vaccines against SARS-CoV-2 infection.

Methods

We conducted a retrospective cohort analysis among adults in Almaty using aggregated vaccination data and individual-level breakthrough COVID-19 cases (≥14 days from 2nd dose) using national surveillance data. We ran time-adjusted Cox-proportional-hazards model with sensitivity analysis accounting for varying entry into vaccinated cohort to assess vaccine effectiveness for each vaccine (measured as 1-adjusted hazard ratios) using the unvaccinated population as reference (N = 565,390). We separately calculated daily cumulative hazards for COVID-19 breakthrough among vaccinated persons by age and vaccination month.

Results

From February 22 to September 1, 2021, in Almaty, 747,558 (57%) adults were fully vaccinated (received 2 doses), and 108,324 COVID-19 cases (11,472 breakthrough) were registered. Vaccine effectiveness against infection was 79% [sensitivity estimates (SE): 74%-82%] for QazVac, 77% (SE: 71%-81%) for Sputnik V, 71% (SE: 69%-72%) for Hayat-Vax, and 70% (SE: 65%-72%) for CoronaVac. Among vaccinated persons, the 90-day follow-up cumulative hazard for breakthrough infection was 2.2%. Cumulative hazard was 2.9% among people aged ≥60 years versus 1.9% among persons aged 18-39 years (p < 0.001), and 1.2% for people vaccinated in February-May versus 3.3% in June-August (p < 0.001).

Conclusion

Our analysis demonstrates high effectiveness of COVID-19 vaccines against infection in Almaty similar to other observational studies. Higher cumulative hazard of breakthrough among people ≥60 years of age and during variant surges warrants targeted booster vaccination campaigns.

Assessing the robustness of COVID-19 vaccine efficacy trials: systematic review and meta-analysis, January 2023

BackgroundVaccines play a crucial role in the response to COVID-19 and their efficacy is thus of great importance.AimTo assess the robustness of COVID-19 vaccine efficacy (VE) trial results using the fragility index (FI) and fragility quotient (FQ) methodology.MethodsWe conducted a Cochrane and PRISMA-compliant systematic review and meta-analysis of COVID-19 VE trials published worldwide until 22 January 2023. We calculated the FI and FQ for all included studies and assessed their associations with selected trial characteristics using Wilcoxon rank sum tests and Kruskal-Wallis H tests. Spearman correlation coefficients and scatter plots were used to quantify the strength of correlation of FIs and FQs with trial characteristics.ResultsOf 6,032 screened records, we included 40 trials with 54 primary outcomes, comprising 909,404 participants with a median sample size per outcome of 13,993 (interquartile range (IQR): 8,534-25,519). The median FI and FQ was 62 (IQR: 22-123) and 0.50% (IQR: 0.24-0.92), respectively. FIs were positively associated with sample size (p < 0.001), and FQs were positively associated with type of blinding (p = 0.023). The Spearman correlation coefficient for FI with sample size was moderately strong (0.607), and weakly positive for FI and FQ with VE (0.138 and 0.161, respectively).ConclusionsThis was the largest study on trial robustness to date. Robustness of COVID-19 VE trials increased with sample size and varied considerably across several other important trial characteristics. The FI and FQ are valuable complementary parameters for the interpretation of trial results and should be reported alongside established trial outcome measures.

Efficacy and effectiveness of inactivated vaccines against symptomatic COVID-19, severe COVID-19, and COVID-19 clinical outcomes in the general population: a systematic review and meta-analysis

Background

Inactivated, whole-virion vaccines have been used extensively in the SARS-CoV-2 pandemic. Its efficacy and effectiveness across regions have not been systematically evaluated. Efficacy refers to how well a vaccine performs in a controlled environment. Effectiveness refers to how well it performs in real world settings.

Methods

This systematic review and meta-analysis reviewed published, peer-reviewed evidence on all WHO-approved inactivated vaccines and evaluated their efficacy and effectiveness against SARS-CoV-2 infection, symptomatic infection, severe clinical outcomes, and severe COVID-19. We searched Pubmed (including MEDLINE), EMBASE (via OVID), Web of Science Core Collection, Web of Science Chinese Science Citation Database, and Clinicaltrials.gov.

Findings

The final pool included 28 studies representing over 32 million individuals reporting efficacy or effectiveness estimates of complete vaccination using any approved inactivated vaccine between January 1, 2019 and June 27, 2022. Evidence was found for efficacy and effectiveness against symptomatic infection (OR 0.21, 95% CI 0.16-0.27, I2 = 28% and OR 0.32, 95% CI 0.16-0.64, I2 = 98%, respectively) and infection (OR 0.53, 95% CI 0.49-0.57, I2 = 90% and OR 0.31, 95% CI 0.24-0.41, I2 = 0%, respectively) for early SARS-CoV-2 variants of concern (VoCs) (Alpha, Delta), and for waning of vaccine effectiveness with more recent VoCs (Gamma, Omicron). Effectiveness remained robust against COVID-related ICU admission (OR 0.21, 95% CI 0.04-1.08, I2 = 99%) and death (OR 0.08, 95% CI 0.00-2.02, I2 = 96%), although effectiveness estimates against hospitalization (OR 0.44, 95% CI 0.37-0.53, I2 = 0%) were inconsistent.

Interpretation

This study showed evidence of efficacy and effectiveness of inactivated vaccines for all outcomes, although inconsistent reporting of key study parameters, high heterogeneity of observational studies, and the small number of studies of particular designs for most outcomes undermined the reliability of the findings. Findings highlight the need for additional research to address these limitations so that more definitive conclusions can be drawn to inform SARS-CoV-2 vaccine development and vaccination policies.

Funding

Health and Medical Research Fund on COVID-19, Health Bureau of the Government of the Hong Kong SAR.

Efficacy of Approved Versus Unapproved Vaccines for Severe Acute Respiratory Syndrome Coronavirus 2 Infection in Randomized Blinded Clinical Trials

Background

Five severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines are approved in North America and/or Europe: Pfizer/BioNTech, Moderna, Janssen, Oxford-AstraZeneca, and Novavax. Other vaccines have been developed, including Sinopharm, SinoVac, QazVac, Covaxin, Soberana, Zifivax, Medicago, Clover, and Cansino, but they are not approved in high-income countries. This meta-analysis compared the efficacy of US Food and Drug Administration (FDA)/European Medicines Agency (EMA)-approved and -unapproved vaccines in randomized clinical trials (RCTs).

Methods

A systematic review of trial registries identified RCTs of SARS-CoV-2 vaccines. Risk of bias was assessed using the Cochrane tool (RoB 2). In the meta-analysis, relative risks of symptomatic infection and severe disease were compared for each vaccine versus placebo, using Cochrane-Mantel Haenszel Tests (random effects method).

Results

Twenty-two RCTs were identified and 1 was excluded for high-risk of bias. Ten RCTs evaluated 5 approved vaccines and 11 RCTs evaluated 9 unapproved vaccines. In the meta-analysis, prevention of symptomatic infection was 84% (95% confidence interval [CI], 68%-92%) for approved vaccines versus 72% (95% CI, 66%-77%) for unapproved vaccines, with no significant difference between vaccine types (P = .12). Prevention of severe SARS-CoV-2 infection was 94% (95% CI, 75%-98%) for approved vaccines versus 86% (95% CI, 76%-92%) for unapproved vaccines (P = .33). The risk of serious adverse events was similar between vaccine types (P = .12).

Conclusions

This meta-analysis of 21 RCTs in 390 459 participants showed no significant difference in efficacy between the FDA/EMA-approved and -unapproved vaccines for symptomatic or severe infection. Differences in study design, endpoint definitions, variants, and infection prevalence may have influenced results. New patent-free vaccines could lower costs of worldwide SARS-CoV-2 vaccination campaigns significantly.

Efficacy of COVID-19 vaccines: a systematic review and network meta-analysis of phase 3 randomized controlled trials

Several vaccines have been approved for the prevention of COVID-19. However, no head-to-head trials comparing their clinical efficacy have been performed. This network meta-analysis aims to identify those, among the competing existing vaccines, conferring the maximum protection against COVID-19. A literature search was done in Medline (via PubMed), Embase and Cochrane Library databases for phase 3 randomized controlled trials evaluating the efficacy of different COVID-19 vaccines. Search results were screened and eligible studies were included to perform a network meta-analysis in software 'R' version 4.1.2 using a random effect model. Cochrane's 'Risk of Bias tool (RoB2)' was used for quality assessment. Raw data from the included studies was used for network meta-analysis. Assessment of inconsistency was not possible as no study compared two or more vaccines directly. A forest plot for indirect comparison of various COVID-19 vaccines was obtained. Rankogram and 'P' scores were obtained to rank the vaccines based on the indirect evidence of their comparative efficacy. A total of 17 randomized controlled trials evaluating the efficacy of 16 COVID-19 vaccines, were included in the network meta-analysis. A total of 361,386 participants was included in this network meta-analysis. Overall risk of bias among included studies was of 'some concern'. All the COVID-19 vaccines had a statistically significant reduction of risk for contracting symptomatic SARS-CoV-2 in comparison to the placebo, however, the maximum protection (RR 0.05) was with BNT126b2. The indirect comparison also revealed BNT126b2 vaccine confers the highest protection against symptomatic SARS-CoV-2 infection in comparison to all others included, with a 'P' score of 0.9771 followed by mRNA-1273, rAD26 & rAD5 and NVX-CoV2373. The evidence generated from this network meta-analysis indicates the good efficacy of all the included vaccines in preventing symptomatic COVID-19 as compared to placebo. The BNT126b2 vaccine was found to provide the highest protection against symptomatic SARS-CoV-2 among all included followed by mRNA-1273, rAD26 & rAD5, NVX-CoV2373 and others.