Modeling the competitive transmission of the Omicron strain and Delta strain of COVID-19.

Since November 2021, there have been cases of COVID-19's Omicron strain spreading in competition with Delta strains in many parts of the world. To explore how these two strains developed in this competitive spread, a new compartmentalized model was established. First, we analyzed the fundamental properties of the model, obtained the expression of the basic reproduction number, proved the local and global asymptotic stability of the disease-free equilibrium. Then by means of the cubic spline interpolation method, we obtained the data of new Omicron and Delta cases in the United States of new cases starting from December 8, 2021, to February 12, 2022. Using the weighted nonlinear least squares estimation method, we fitted six time series (cumulative confirmed cases, cumulative deaths, new cases, new deaths, new Omicron cases, and new Delta cases), got estimates of the unknown parameters, and obtained an approximation of the basic reproduction number in the United States during this time period as R 0 ≈ 1.5165 . Finally, each control strategy was evaluated by cost-effectiveness analysis to obtain the optimal control strategy under different perspectives. The results not only show the competitive transmission characteristics of the new strain and existing strain, but also provide scientific suggestions for effectively controlling the spread of these strains.

Safety and immunogenicity of homologous versus heterologous booster dose with AZD1222, mRNA-1273, or MVC-COV1901 SARS-CoV-2 vaccines in adults: An observer-blinded, multi-center, phase 2 randomized trial.

OBJECTIVES: To report the safety and immunogenicity profile of a protein subunit vaccine (MVC-COV1901) compared to AZD1222 and mRNA-1273 when given as a third (booster) dose to individuals who have completed different primary vaccine regimens. METHODS: Individuals were classified according to their primary vaccine regimens, including two-dose MVC-COV1901, AZD1222, or mRNA-1273. A third dose of either half-dose MVC-COV1901, full-dose MVC-COV1901, standard-dose AZD1222, half-dose mRNA-1273 was administered in a 1:1:1:1 treatment ratio to individuals with an interval range of 84-365 days after the second dose. Endpoints included safety, humoral immunogenicity, and cell-mediated immune response on trial days 15 and 29. Exploratory endpoint included testing against variants of concern (Omicron). RESULTS: Overall, 803 participants were randomized and boosted - 201 received half-dose MVC-COV1901, 196 received full-dose MVC-COV1901, 203 received AZD1222, and 203 received half-dose mRNA-1273. Reactogenicity was mild to moderate, and less in the MVC-COV1901 booster group. Heterologous boosting provided the best immunogenic response. Boosting with mRNA-1273 in MVC-COV1901 primed individuals induced the highest antibody titers, even against Omicron, and cell-mediated immune response. CONCLUSIONS: Overall, MVC-COV1901 as a booster showed the best safety profiles. MVC-COV1901 as a primary series, with either homologous or heterologous booster, elicited the highest immunogenic response. CLINICALTRIALS: gov registration NCT05197153.

Comparison of Delta and Omicron variant of COVID-19 infection cases in Montenegro

Introduction/Objective At the end of 2021, Omicron wave (B.1.1.529) SARS-CoV-2 variant superseded the Delta variant (B.1.617). The main goal of the research is to provide a detailed and comprehensive presentation of data related to people infected with the coronavirus in Montenegro. The specific goal of the research is to determine whether virus mutations influenced the course of the epidemic during its two-year duration. Methods This is a retrospective study. We used data from the Institute of Public Health of Montenegro. Our sample consisted of 127,134 people who tested positive for Delta or Omicron infection aged 0–100 years, who had a positive PCR test for COVID-19 between August 17, 2021 and April 17, 2022. Results The respondents aged 40–49 years were taken as a reference group for age. The results showed that the age group from 20 to 29 years old was affected 1.03 times more than the reference group – per-sons belonging to the age group of 30–39 years were affected 1.07 times more than the reference group. The Central region was taken as the reference group for the region. The results showed that people who live in southern region got sick 1.14 times more often and people who live in northern region got sick 1.20 times less than people from the central region. Conclusion The biggest predictor that a person would get sick is the age group. Also, the predictor is the region, and in our research, it was southern region. © 2023, Serbia Medical Society. All rights reserved.

An evaluation of the safety and immunogenicity of MVC-COV1901: Results of an interim analysis of a phase III, parallel group, randomized, double-blind, active-controlled immunobridging study in Paraguay.

BACKGROUND: Data from previous studies of the MVC-COV1901 vaccine, a subunit vaccine against SARS-CoV-2 based on the stable prefusion spike protein (S-2P) adjuvanted with CpG 1018 adjuvant and aluminum hydroxide, suggest that the vaccine is generally safe and elicits a good immune response in healthy adults and adolescents. By comparing with AZD1222, this study adds to the findings from previous trials and further evaluates the breadth of protection offered by MVC-COV1901. METHODS: In this phase 3, parallel group, randomized, double-blind, active-controlled trial conducted in 2 sites in Paraguay, we assigned adults aged 18-91 years in a 1:1 ratio to receive intramuscular doses of MVC-COV1901 or AZD1222 administered as scheduled in the clinical trial. Serum samples were collected on the day of vaccination and 14 days after the second dose. Primary and secondary safety and immunogenicity endpoints were assessed. In addition, other outcomes investigated were cross-reactive immunity against the Omicron strain and the induction of IgG subclasses. RESULTS: A total of 1,030 participants underwent randomization. Safety data was derived from this set while primary immunogenicity data involved a per-protocol immunogenicity (PPI) subset including 225 participants. Among the participants, 58% are seropositive at baseline. When compared against AZD1222, MVC-COV1901 exhibited superiority in terms of neutralizing antibody titers and non-inferiority in terms of seroconversion rates. Reactogenicity was generally mild and no serious adverse event was attributable to MVC-COV1901. Both vaccines have a Th1-biased response predominated by the production of IgG1 and IgG3 subclasses. Omicron-neutralizing titers were 44.5 times lower compared to wildtype-neutralizing titers among seronegative individuals at baseline. This fold-reduction was 3.0 times among the seropositive. CONCLUSION: Safety and immunogenicity data of MVC-COV1901 from the study in Paraguay confirm previous results. The previous infection coupled with vaccination of this vaccine may offer protection against the Omicron strain though its durability is still unknown.

Vaccination efficacy against post-COVID-19 symptoms in Delta and Omicron waves: a prospective cohort in East Indonesia

The post COVID-19 symptoms affect the productivity and the quality of life among survivors. It is imperative to identify the effect of virus variants and the vaccination against post-COVID-19 symptoms. There were 242 participants from the eastern part of Indonesia diagnosed with COVID-19 during July 2021-July to 2022 were recruited online. The participants underwent data collection and semi-clinical follow-up for post-COVID-19 symptoms within 30 days after the first symptoms or from the diagnosis day using a validated clinical questionnaire and physician confirmation. Fatigue was the most reported post-COVID-19 symptom (27.7%), followed by chronic cough (21.5%) and headache (15.3%). Adjusted by confounding factors in hierarchical logistic regression, the differences in post-COVID-19 symptoms were insignificant across different variants. Regarding vaccine efficacy against three post-COVID-19 symptoms, people with two-dose vaccination significantly reported lower post-COVID-19 chronic cough (adjusted Odds Ratio 0.244 95% CI OR 0.071-0.838), but the protection against fatigue and the chronic headache was insignificant. There is an indication that vaccine efficacy may be waning along with the emerging new variants. © 2023, Intelektual Pustaka Media Utama. All rights reserved.

Optimal control and cost-effectiveness analysis of a new COVID-19 model for Omicron strain.

Omicron, a mutant strain of COVID-19, has been sweeping the world since November 2021. A major characteristic of Omicron transmission is that it is less harmful to healthy adults, but more dangerous for people with underlying disease, the elderly, or children. To simulate the spread of Omicron in the population, we developed a new 9-dimensional mathematical model with high-risk and low-risk exposures. Then we analyzed its dynamic properties and obtain the basic reproduction number R 0 . With the data of confirmed cases from March 1, 2022 published on the official website of Shanghai, China, we used the weighted nonlinear least square estimation method to estimate the parameters, and get the basic reproduction number R 0 ≈ 1 . 5118 . Finally, we considered three control measures (isolation, detection and treatment), and studied the optimal control strategy and cost-effectiveness analysis of the model. The control strategy G is determined to be the optimal control strategy from the purpose of making fewer people infected. In strategy G, the three human control measures contain six control variables, and the control strength of these variables needs to be varied according to the pattern shown in Figure 11, so that the number of infections can be minimized and the percentage of reduction of infections can reach more than 95%.

Strain wars 2: Binding constants, enthalpies, entropies, Gibbs energies and rates of binding of SARS-CoV-2 variants.

SARS-CoV-2 virus is the cause of COVID-19 pandemic and belongs to RNA viruses, showing great tendency to mutate. Several dozens of mutations have been observed on the SARS-CoV-2 virus, during the last two years. Some of the mutated strains show a greater infectivity and are capable of suppressing the earlier strains, through interference. In this work, kinetic and thermodynamic properties were calculated for strains characterized by various numbers and locations of mutations. It was shown that mutations lead to changes in chemical composition, thermodynamic properties and infectivity. Through competition, the phenomenon of interference of various SARS-CoV-2 strains was explained, which results in suppression of the wild type by mutant strains. Standard Gibbs energy of binding and binding constant for the Omicron (B.1.1.529) strain were found to be ΔBG° = -45.96 kJ/mol and KB = 1.13 ∙ 10+8 M-1, respectively.

Omicron variant of SARS-CoV-2 imposes a new challenge for the global public health.

Since its first discovery, the Omicron variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has evoked another wave of infection and caused global concern and panic. Moreover, although the data are still limited, Omicron showed highly concerning characteristics, including higher transmissibility, extensive immune escape and potentially altered host range. We interpreted these characteristics based on currently available data and outlined some urgent questions, calling for a more comprehensive investigation.