Mental health and associated risk factors of Puerto Rico Post-Hurricane María.

BACKGROUND: Mental health disorders have an increased prevalence in communities that experienced devastating natural disasters. Maria, a category 5 hurricane, struck Puerto Rico on September 20, 2017, weakening the island's power grid, destroying buildings and homes, and limiting access to water, food, and health care services. This study characterized sociodemographic and behavioral variables and their association with mental health outcomes in the aftermath of Hurricane Maria. METHODS: A sample of 998 Puerto Ricans affected by Hurricane Maria was surveyed between December 2017 and September 2018. Participants completed a 5-tool questionnaire: Post-Hurricane Distress Scale, Kessler K6, Patient Health Questionnaire 9, Generalized Anxiety Disorder (GAD) 7, and Post-Traumatic Stress Disorder checklist for DSM-V. The associations of sociodemographic variables and risk factors with mental health disorder risk outcomes were analyzed using logistic regression analysis. RESULTS: Most respondents reported experiencing hurricane-related stressors. Urban respondents reported a higher incidence of exposure to stressors when compared to rural respondents. Low income (OR = 3.66; 95% CI = 1.34-11.400; p < 0.05) and level of education (OR = 4.38; 95% CI = 1.20-15.800; p < 0.05) were associated with increased risk for severe mental illness (SMI), while being employed was correlated with lower risk for GAD (OR = 0.48; 95% CI = 0.275-0.811; p < 0.01) and lower risk for SIM (OR = 0.68; 95% CI = 0.483-0.952; p < 0.05). Abuse of prescribed narcotics was associated with an increased risk for depression (OR = 2.94; 95% CI = 1.101-7.721; p < 0.05), while illicit drug use was associated with increased risk for GAD (OR = 6.56; 95% CI = 1.414-39.54; p < 0.05). CONCLUSION: Findings underline the necessity for implementing a post-natural disaster response plan to address mental health with community-based social interventions.

IgGκ Signal Peptide Enhances the Efficacy of an Influenza Vector Vaccine against Respiratory Syncytial Virus Infection in Mice.

Intranasal vaccination using influenza vectors is a promising approach to developing vaccines against respiratory pathogens due to the activation of the mucosa-associated immune response. However, there is no clear evidence of a vector design that could be considered preferable. To find the optimal structure of an influenza vector with a modified NS genomic segment, we constructed four vector expressing identical transgene sequences inherited from the F protein of the respiratory syncytial virus (RSV). Two vectors were designed aiming at transgene accumulation in the cytosol. Another two were supplemented with an IgGκ signal peptide prior to the transgene for its extracellular delivery. Surprisingly, adding the IgGκ substantially enhanced the T-cell immune response to the CD8 epitope of the transgene. Moreover, this strategy allowed us to obtain a better protection of mice from the RSV challenge after a single intranasal immunization. Protection was achieved without antibodies, mediated by a balanced T-cell immune response including the formation of the RSV specific effector CD8+ IFNγ+/IL10+-producing cells and the accumulation of Treg cells preventing immunopathology in the lungs of infected mice. In addition to the presented method for optimizing the influenza vector, our results highlight the possibility of achieving protection against RSV through a respiratory-associated T-cell immune response alone.

Preclinical Evaluation of TB/FLU-04L-An Intranasal Influenza Vector-Based Boost Vaccine against Tuberculosis.

Tuberculosis is a major global threat to human health. Since the widely used BCG vaccine is poorly effective in adults, there is a demand for the development of a new type of boost tuberculosis vaccine. We designed a novel intranasal tuberculosis vaccine candidate, TB/FLU-04L, which is based on an attenuated influenza A virus vector encoding two mycobacterium antigens, Ag85A and ESAT-6. As tuberculosis is an airborne disease, the ability to induce mucosal immunity is one of the potential advantages of influenza vectors. Sequences of ESAT-6 and Ag85A antigens were inserted into the NS1 open reading frame of the influenza A virus to replace the deleted carboxyl part of the NS1 protein. The vector expressing chimeric NS1 protein appeared to be genetically stable and replication-deficient in mice and non-human primates. Intranasal immunization of C57BL/6 mice or cynomolgus macaques with the TB/FLU-04L vaccine candidate induced Mtb-specific Th1 immune response. Single TB/FLU-04L immunization in mice showed commensurate levels of protection in comparison to BCG and significantly increased the protective effect of BCG when applied in a "prime-boost" scheme. Our findings show that intranasal immunization with the TB/FLU-04L vaccine, which carries two mycobacterium antigens, is safe, and induces a protective immune response against virulent M. tuberculosis.

Safety and immunogenicity of the novel seasonal preservative- and adjuvant-free influenza vaccine: Blind, randomized, and placebo-controlled trial.

The producers of influenza vaccines are not capable today to meet the global demand for an influenza vaccine in case of pandemic, so the World Health Organization recommends to develop the own influenza vaccine production in each country. A domestic preservative- and adjuvant-free trivalent split vaccine against seasonal influenza was developed at the Research Institute for Biological Safety Problems. The paper presents the results of assessing safety and immunogenicity of the influenza split vaccine after single immunization of healthy volunteers aged 18-50 years in the course of Phase I Clinical Trials. This study was randomized, blind, and placebo-controlled. The volunteers were intramuscularly vaccinated with a dose of split vaccine or placebo. The study has shown that all local and systemic reactions had low degree of manifestation and short-term character, so there was no need in medication. Serious side effects were not observed. On day 21 post vaccination the portion of vaccinated persons with fourfold seroconversions to influenza А/H1N1pdm09 virus was 100.0%, to influenza А/H3N2 virus-95.5%, to influenza B virus-81.8%, and in placebo group this index was 0%. Seroprotection rates against influenza А/H1N1pdm09, А/H3N2 and B viruses were 95.5, 86.3, and 72.7%, respectively. Geometric mean titers (GMT) of antibodies by day 21 post vaccination reached 175.7 for influenza А/H1N1pdm09 virus, 64.2 for influenza А/H3N2 virus, and 37.6 for influenza B virus; in placebo group GMT growth was not observed. So, the seasonal influenza split vaccine is well tolerated and fits all immunogenicity criteria for human influenza vaccines.

A novel preservative-free seasonal influenza vaccine safety and immune response study in the frame of preclinical research.

The paper describes the results of preclinical testing of the preparation "Vaccine allantoic split-virus inactivated against seasonal influenza." Acute toxicity and local irritating effect, anaphylactic reactions to different antigens (vaccine and ovalbumin), delayed-type hypersensitivity to ram erythrocytes, humoral immune response in hemaggtination reaction, immunogenic activity was studied in laboratory animals of various species (mice, rats, guinea pigs). Comparative analysis of the results from testing immunogenic activity of the preparation under study and the commercial influenza vaccines was performed. The preclinical testing has demonstrated safety and immune response of the seasonal split influenza vaccine, so it may be recommended for clinical study on limited contingent of volunteers.

A genetically adjuvanted influenza B virus vector increases immunogenicity and protective efficacy in mice.

The existence of multiple antigenically distinct types and subtypes of influenza viruses allows the construction of a multivalent vector system for the mucosal delivery of foreign sequences. Influenza A viruses have been exploited successfully for the expression of extraneous antigens as well as immunostimulatory molecules. In this study, we describe the development of an influenza B virus vector whose functional part of the interferon antagonist NS1 was replaced by human interleukin 2 (IL2) as a genetic adjuvant. We demonstrate that IL2 expressed by this viral vector displays immune adjuvant activity in immunized mice. Animals vaccinated with the IL2 viral vector showed an increased hemagglutination inhibition antibody response and higher protective efficacy after challenge with a wild-type influenza B virus when compared to mice vaccinated with a control virus. Our results demonstrate that it is feasible to construct influenza B vaccine strains expressing immune-potentiating foreign sequences from the NS genomic segment. Based on these data, it is now hypothetically possible to create a trivalent (or quadrivalent) live attenuated influenza vaccine in which each component expresses a selected genetic adjuvant with tailored expression levels.

Adaptive mutation in nuclear export protein allows stable transgene expression in a chimaeric influenza A virus vector.

The development of influenza virus vectors with long insertions of foreign sequences remains difficult due to the small size and instable nature of the virus. Here, we used the influenza virus inherent property of self-optimization to generate a vector stably expressing long transgenes from the NS1 protein ORF. This was achieved by continuous selection of bright fluorescent plaques of a GFP-expressing vector during multiple passages in mouse B16f1 cells. The newly generated vector acquired stability in IFN-competent cell lines and in vivo in murine lungs. Although improved vector fitness was associated with the appearance of four coding mutations in the polymerase (PB2), haemagglutinin and non-structural (NS) segments, the stability of the transgene expression was dependent primarily on the single mutation Q20R in the nuclear export protein (NEP). Importantly, a longer insert, such as a cassette of 1299 nt encoding two Mycobacterium tuberculosis Esat6 and Ag85A proteins, could substitute for the GFP transgene. Thus, the inherent property of the influenza virus to adapt can also be used to adjust a vector backbone to give stable expression of long transgenes.

Transformative vaccination: A pentavalent shield against COVID-19 and influenza with betulin-based adjuvant for enhanced immunity.

The development of an effective combined vaccine represents a crucial strategy for preventing outbreaks of infectious diseases and reducing the burden on healthcare resources. Developing a combined vaccine against both influenza and the coronavirus is a promising approach, but it is still in the early stages of development. This paper reports on a novel combined pentavalent candidate vaccine that has shown promising results in mice, with statistically significant differences in mean antibody titer against the coronavirus and the influenza antigens compared to placebo. We have shown that the coronavirus antigen is capable of inducing an immune response autonomously, regardless of the presence of the influenza antigens in a combined vaccine. On the other hand, the presence of the coronavirus antigen in a combined vaccine showed to enhance the immune response against some of the studied influenza antigens, suggesting that these antigens may act in synergy and elicit an enhanced immune response. The absence of dose-dependent difference in mean antibody titer within the same antigenic groups of vaccine preparations suggested that even small amounts of the coronavirus and the influenza antigens could induce an immune response just as good as high-dose vaccine preparations, which certainly has important safety and cost implications. The vaccine is soon to be ready for clinical trials and mass production.

Phase I Clinical Study of the Subunit Betulin-Adjuvanted Tetravalent Candidate Influenza Vaccine TetraFluBet.

OBJECTIVES: This study aimed to determine the safety, tolerability and immunogenicity of TetraFluBet, an inactivated subunit influenza vaccine that contains a corpuscular immuno-adjuvant derived from natural betulin. METHODS: We conducted a prospective, randomized, open-labeled, single-center, phase I trial. The study was conducted in two stages: 5 volunteers in stage I and 25 volunteers in stage II. Eligible participants received one single dose (20 µg/0.5 mL) of TetraFluBet intramuscularly. Participants were followed for adverse events and reactogenicity. Seroconversion rate, seroprotection level, geometric mean titers (GMTs) of virus-neutralizing antibodies, IFN-γ induction and cell-mediated immunity were assessed. RESULTS: A total of 30 participants were enrolled. No vaccine-related serious adverse events were observed. The proportions of study participants with 4-fold seroconversions assessed by the HI assay (with 95% CIs) were 80.0% (62.7; 90.5), 70.0% (52.1; 83.3), 63.3% (45.5; 78.1) and 73.3% (55.6; 85.8) for influenza virus subtypes A (H1N1), A (H3N2), B1 and B2, respectively. Seroprotection levels (with 95% CIs) were 83.3% (66.4; 92.7), 83.3% (66.4; 92.7), 73.3% (55.6; 85.8) and 66.7% (48.8; 80.8), respectively. The fold increases in the GMTs of virus-neutralizing antibodies for subtype H1N1 was 6.50, for subtype H3N2 was 3.03, for subtype B1 was 3.56 and for subtype B2 was 6.07. The population of cytotoxic T-cells increased significantly in the post-vaccination period, indicating a strong CD3+CD8+ response. CONCLUSIONS: TetraFluBet tetravalent inactivated subunit vaccine with adjuvant demonstrated pronounced immunogenic properties, leading to the formation of both specific humoral and cellular immunity at a 20 µg dose.

TB/FLU-06E Influenza Vector-Based Vaccine in the Complex Therapy of Drug-Susceptible and Drug-Resistant Experimental Tuberculosis.

The steady rise of drug-resistant tuberculosis (TB), which renders standard therapy regimens ineffective, necessitates the development of innovative treatment approaches. Immunotherapeutic vaccines have the potential to effectively regulate the anti-TB immune response and enhance the efficacy of anti-TB treatment. In the present study, we aimed to evaluate the potency of the mucosal vector vaccine TB/FLU-06E as part of a complex treatment regimen for drug-susceptible (DS) or drug-resistant (DR) tuberculosis in C57BL/6 mice. Incorporating TB/FLU-06E into the treatment protocol significantly increased the effectiveness of therapy for both forms of tuberculosis. It was evidenced by higher survival rates and reduced pulmonary bacterial load (1.83 lg CFU for DS tuberculosis and 0.93 lg CFU for DR tuberculosis). Furthermore, the treatment reduced pathomorphological lesions in the lungs and stimulated the local and systemic T-helper 1 (Th1) and cytotoxic T-lymphocyte (CTL) anti-TB immune responses. Thus, therapeutic immunization with the TB/FLU-06E vaccine significantly enhances the efficacy of tuberculosis treatment, which is particularly important in DR tuberculosis.

Evaluation of the immunotoxicity and allergenicity of a new intranasal influenza vector vaccine against tuberculosis carrying TB10.4 and HspX antigens.

Objectives: A new vaccine candidate TB/FLU-05E has been developed at the Smorodintsev Research Institute of Influenza (Russia). The vaccine is based on the attenuated influenza strain A/PR8/NS124-TB10.4-2A-HspX that expresses mycobacterial antigens TB10.4 and HspX. This article describes the results of preclinical immunotoxicity and allergenicity studies of the new vector vaccine TB/FLU-05E against tuberculosis. Materials and Methods: The experiments were conducted on male CBA mice, С57/black/6 mice, and guinea pigs. The vaccine candidate was administered intranasally (7.7 lg TCID50/animal and 8.0 lg TCID50/animal) twice at a 21-day interval. The immunotoxic properties of the vaccine were assessed in mice according to the following parameters: spleen and thymus weight and their organ-to-body weight ratio, splenic and thymic cellularity, hemagglutination titer assay, delayed-type hypersensitivity test, and phagocytic activity of peritoneal macrophages. Histological examination of the thymus and spleen and white blood cell counts were also performed. Allergenicity of the vaccine was assessed in guinea pigs using conjunctival and general anaphylaxis reaction tests. Results: The results showed that double immunization with the TB/FLU-05E vaccine did not affect the phagocytic activity of peritoneal macrophages, cellular and humoral immunity after immunization with a heterologous antigen (sheep red blood cells), or the organ-to-body weight ratio of immunocompetent organs (thymus and spleen). The vaccine candidate demonstrated no allergenic properties. Conclusion: According to the results of this study, the TB/FLU-05E vaccine is well-tolerated by the immune system and demonstrates no immunotoxicity or allergenicity.

Longitudinal Analysis of Neuraminidase and Hemagglutinin Antibodies to Influenza A Viruses after Immunization with Seasonal Inactivated Influenza Vaccines.

Neuraminidase (NA)-based immunity could reduce the harmful impact of novel antigenic variants of influenza viruses. The detection of neuraminidase-inhibiting (NI) antibodies in parallel with anti-hemagglutinin (HA) antibodies may enhance research on the immunogenicity and duration of antibody responses to influenza vaccines. To assess anti-NA antibodies after vaccination with seasonal inactivated influenza vaccines, we used the enzyme-linked lectin assay, and anti-HA antibodies were detected in the hemagglutination inhibition assay. The dynamics of the anti-NA antibody response differed depending on the virus subtype: antibodies to A/H3N2 virus neuraminidase increased later than antibodies to A/H1N1pdm09 subtype neuraminidase and persisted longer. In contrast to HA antibodies, the fold increase in antibody titers to NA after vaccination poorly depended on the preexisting level. At the same time, NA antibody levels after vaccination directly correlated with titers before vaccination. A difference was found in response to NA antigen between split and subunit-adjuvanted vaccines and in NA functional activity in the vaccine formulations.

Safety and Immunogenicity of Betuvax-CoV-2, an RBD-Fc-Based SARS-CoV-2 Recombinant Vaccine: Preliminary Results of the First-in-Human, Randomized, Double-Blind, Placebo-Controlled Phase I/II Clinical Trial.

COVID-19, being a life-threatening infection that evolves rapidly, remains a major public health concern calling for the development of vaccines with broad protection against different pathogenic strains and high immunogenicity. Aside from this, other concerns in mass immunization settings are also the scalability of production and relative affordability of the technology. In that regard, adjuvanted protein vaccines with particles mimicking the virus stand out among known vaccine technologies. The "Betuvax-CoV-2" vaccine, developed on the basis of a recombinant protein and an adjuvant, has already been tested in preclinical studies and has advanced to clinical evaluation. Open, double-blinded, placebo-controlled, randomized phase I/II clinical trial of the "Betuvax-CoV-2," recombinant protein subunit vaccine based on the S-protein RBD fused with the Fc-fragment of IgG, was conducted to evaluate safety and immunogenicity in response to the vaccination. METHODS: In the phase I/II clinical trial, 116 healthy adult men and women, ages 18-58, were enrolled: 20 in Stage I, and 96 in Stage II. In Stage I, 20 µg of the vaccine was administered intramuscularly on day 2, and either 5 µg (group 1) or 20 µg (group 2) on day 30. In Stage II, 20 µg of the vaccine was administered intramuscularly on day 2, and either 5 µg (group 3) or 20 µg (group 4) on day 30. In group 5, both injections were replaced with placebo. The primary outcome measures were safety (number of participants with adverse events throughout the study) and antigen-specific humoral immunity (SARS-CoV-2-specific antibodies measured by ELISA and CMIA). Antigen-specific cell-mediated immunity and changes in neutralizing antibodies (detected with a SARS-CoV-2 neutralization assay) were measured as a secondary outcome. The trial is registered with ClinicalTrials.gov (Study Identifier: NCT05270954). FINDINGS: Both vaccine formulations (20 µg + 5 µg and 20 µg + 20 µg) were safe and well tolerated. Most adverse events were mild, and no serious adverse events were detected. On day 51,anti-SARS-CoV-2 total and IgG antibody titers and anti-SARS-CoV-2 neutralizing antibodies were significantly higher in the vaccine groups (both formulations) than in the placebo. A more pronounced CD4+-mediated immune response was observed in the group of volunteers administered with the 20 + 20 µg vaccine formulation. INTERPRETATIONS: RBD-Fc-based COVID-19 "Betuvax-CoV-2" vaccine in doses (20 + 5 µg and 20 + 20 µg) demonstrated an excellent safety profile and induced a strong humoral response. Further research on the protective effectiveness of the "Betuvax-CoV-2" vaccine for the prevention of COVID-19 is on its way.

SARS-CoV-2 escape from cytotoxic T cells during long-term COVID-19.

Evolution of SARS-CoV-2 in immunocompromised hosts may result in novel variants with changed properties. While escape from humoral immunity certainly contributes to intra-host evolution, escape from cellular immunity is poorly understood. Here, we report a case of long-term COVID-19 in an immunocompromised patient with non-Hodgkin's lymphoma who received treatment with rituximab and lacked neutralizing antibodies. Over the 318 days of the disease, the SARS-CoV-2 genome gained a total of 40 changes, 34 of which were present by the end of the study period. Among the acquired mutations, 12 reduced or prevented the binding of known immunogenic SARS-CoV-2 HLA class I antigens. By experimentally assessing the effect of a subset of the escape mutations, we show that they resulted in a loss of as much as ~1% of effector CD8 T cell response. Our results indicate that CD8 T cell escape represents a major underappreciated contributor to SARS-CoV-2 evolution in humans.

Preclinical Safety Evaluation: Acute and Repeated-Dose Toxicity of a New Intranasal Recombinant Vector Vaccine TB/FLU-04L Against Tuberculosis.

BACKGROUND: Vaccination against tuberculosis is one of the most successful medical measures to reduce morbidity and mortality. The BCG vaccine has been in use for more than 100 years, but its efficacy is still controversial. New vaccine candidates may offer better protection than available BCG vaccine. In this work, we studied the acute and the repeated-dose toxicity study of a new vector vaccine TB/Flu-04L against tuberculosis. MATERIALS AND METHODS: The study was conducted on 60 BALB/c mice and 150 Wistar rats. The vaccine was administered intranasally and intravenously for the acute toxicity study. For the repeated-dose toxicity study, rats were intranasally immunized by 6.5 log10 TCID50 or 7.5 log10 TCID50 three times with 21-day intervals. Mortality, temperature, body weight, food and water consumption, hematological and biochemical parameters, urine analysis, as well as cardiovascular, respiratory, and central nervous system parameters were evaluated. A macroscopic examination of internal organs was performed. RESULTS: The TB/FLU-04L vaccine did not cause death among the mice and rats in the acute toxicity study. There were no pathological abnormalities in animal condition, behavior, food and water consumption, temperature, and body weight during the observation period. The results suggest that intranasal repeated-dose administration of the TB/FLU-04L vaccine does not exhibit significant toxicity in rats.Hematological and biochemistry analysis and the histological examination identified no toxicity-associated changes. CONCLUSIONS: The toxicity study in mice and rats showed that the intranasal vector vaccine TB/FLU-04L had no toxic effect. The tests confirm no adverse effects for laboratory animals in the studied parameters.

A New Intranasal Influenza Vector-Based Vaccine TB/FLU-04L Against Tuberculosis: Preclinical Safety Studies.

A recombinant vector vaccine TB/FLU-04L for the prevention of tuberculosis was developed in RIBSP CS MES RK and SRII. The vaccine is based on the attenuated influenza strain Flu NS106/ESAT-6_Ag85A expressing mycobacterial antigens Esat-6 and Ag85A. This research aimed to conduct pre-clinical safety studies of the vaccine as one of the basic and mandatory stages in the development and introduction of immunobiological preparations. The studies were performed at the research centers of the Republic of Kazakhstan and the Russian Federation.The experiment was conducted on ferrets, monkeys, and rabbits. The TB/FLU-04L vaccine was administered intranasally (7.5 lg TCID50/animal). The clinical signs, body weight, temperature, hematological parameters, and local irritant effects were monitored throughout the study. The results of the study demonstrated the safety of the TB/FLU-04L intranasal vector vaccine against tuberculosis since its administration in laboratory animals led to no adverse effects in any of the monitored parameters. No influenza A virus particles were isolated from samples of nasal washes.

Post-Hurricane Distress Scale (PHDS): Determination of General and Disorder-Specific Cutoff Scores.

The Post-Hurricane Distress Scale (PHDS) was developed to assess mental health risk in the aftermath of hurricanes. We derive both disorder-specific cutoff values and a single nonspecific cutoff for the PHDS for field use by disaster relief and mental health workers. Data from 672 adult residents of Puerto Rico, sampled 3 to 12 months after Hurricane Maria, were collected. Participants completed a five-tool questionnaire packet: PHDS, Kessler K6, Patient Health Questionnaire 9, Generalized Anxiety Disorder 7, and Post-Traumatic Stress Disorder Checklist for DSM V (PCL-5). ROC curves, AUC values, sensitivities, specificities, Youden's index, and LR+ ratios are reported. The recommended single cutoff value for the PHDS is 41, whereby a respondent with a PHDS score of 41 or above is deemed high-risk for a mental health disorder. The single field use PHDS cutoff demonstrated high specificity (0.80), an LR + ratio (2.84), and a sensitivity of 0.56. The mean ROC values of PHDS for Kessler K6, Patient Health Questionnaire 9, Generalized Anxiety Disorder 7, and PCL-5 were all above 0.74. The derived cutoff for the PHDS allows efficient assessment of respondents' and/or a community's risk status for mental health disorders in the aftermath of hurricanes and natural disasters.

Design and Immunological Properties of the Novel Subunit Virus-like Vaccine against SARS-CoV-2.

The COVID-19 pandemic is ongoing, and the need for safe and effective vaccines to prevent infection and to control spread of the virus remains urgent. Here, we report the development of a SARS-CoV-2 subunit vaccine candidate (Betuvax-CoV-2) based on RBD and SD1 domains of the spike (S) protein fused to a human IgG1 Fc fragment. The antigen is adsorbed on betulin adjuvant, forming spherical particles with a size of 100-180 nm, mimicking the size of viral particles. Here we confirm the potent immunostimulatory activity of betulin adjuvant, and demonstrate that two immunizations of mice with Betuvax-CoV-2 elicited high titers of RBD-specific antibodies. The candidate vaccine was also effective in stimulating a neutralizing antibody response and T cell immunity. The results indicate that Betuvax-CoV-2 has good potential for further development as an effective vaccine against SARS-CoV-2.

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.

Background: Vaccination remains the primary measure to prevent the spread of the SARS-CoV-2 virus, further necessitating the use of effective licensed vaccines. Methods: From Dec 25, 2020, to July 11, 2021, we conducted a multicenter, randomised, single-blind, placebo-controlled phase 3 efficacy trial of the QazCovid-in® vaccine with a 180-day follow-up period in three clinical centres in Kazakhstan. A total of 3000 eligible participants aged 18 years or older were randomly assigned (4:1) to receive two doses of the vaccine (5 µg each, 21 days apart) or placebo administered intramuscularly. QazCovid-in® is a whole-virion formaldehyde-inactivated anti-COVID-19 vaccine, adjuvanted with aluminium hydroxide. The primary endpoint was the incidence of symptomatic cases of the SARS-CoV-2 infection confirmed by RT-PCR starting from day 14 after the first immunisation. The trial was registered with ClinicalTrials.gov NCT04691908. Findings: The QazCovid-in® vaccine was safe over the 6-month monitoring period after two intramuscular immunisations inducing only local short-lived adverse events. The concomitant diseases of participants did not affect the vaccine safety. Out of 2400 vaccinated participants, 31 were diagnosed with COVID-19; 43 COVID-19 cases were recorded in 600 placebo participants with onset of 14 days after the first dose within the 180-day observation period. Only one severe COVID-19 case was identified in a vaccine recipient with a comorbid chronic heart failure. The protective efficacy of the QazCovid-in® vaccine reached 82·0% (95% CI 71.1-88.5) within the 180-day observation period. Interpretation: Two immunisations with the inactivated QazCovid-in® vaccine achieved 82·0% (95% CI 71.1-88.5) protective efficacy against COVID-19 within a 180-day follow-up period. Funding: The work was funded by the Science Committee of the Ministry of Education and Science of Kazakhstan within the framework of the Scientific and Technical Program "Development of a vaccine against coronavirus infection COVID-19". State registration number 0.0927.

SARS-CoV-2 Subunit Virus-like Vaccine Demonstrates High Safety Profile and Protective Efficacy: Preclinical Study.

Public health threat coming from a rapidly developing COVID-19 pandemic calls for developing safe and effective vaccines with innovative designs. This paper presents preclinical trial results of "Betuvax-CoV-2", a vaccine developed as a subunit vaccine containing a recombinant RBD-Fc fusion protein and betulin-based spherical virus-like nanoparticles as an adjuvant ("Betuspheres"). The study aimed to demonstrate vaccine safety in mice, rats, and Chinchilla rabbits through acute, subchronic, and reproductive toxicity studies. Along with safety, the vaccine demonstrated protective efficacy through SARS-CoV-2-neutralizing antibody production in mice, rats, hamsters, rabbits, and primates (rhesus macaque), and lung damage and infection protection in hamsters and rhesus macaque model. Eventually, "Betuvax-CoV-2" was proved to confer superior efficacy and protection against the SARS-CoV-2 in preclinical studies. Based on the above results, the vaccine was enabled to enter clinical trials that are currently underway.