Herd immunity or suppression strategy to combat COVID-19

Morphology and Function of Red Blood Cells in COVID-19 Patients: Current Overview 2023

In severe cases, SARS-CoV-2 infection leads to severe respiratory failure. Although angiotensin-converting enzyme 2 (ACE2) receptors are not expressed in red blood cells, SARS-CoV-2 can interact with red blood cells (RBCs) via several receptors or auxiliary membrane proteins. Recent data show that viral infection causes significant damage to the RBCs, altering their morphology, deformability, and aggregability. Loss of RBC deformability and/or increased aggregability favors the development of thrombotic processes in the microcirculation, as has been described to occur in COVID-19 patients. In addition, many patients also develop systemic endotheliitis associated with generalized coagulopathy. This manifests itself clinically as obstructive microthrombi in the area of the medium and smallest vessels, which can affect all internal organs. It is thought that such changes in the RBCs may contribute to the microangiopathy/microthrombosis associated with COVID-19 and may result in impaired capillary blood flow and tissue oxygenation.

Investigation of the Side Effects of COVID-19 Vaccines in Southern Iran: A Cross-Sectional Study

The COVID-19 disease is a newly emerging disease, and the COVID-19 vaccine is one of the necessities to prevent this disease. The present study aimed to investigate the side effects of COVID-19 vaccines in southern Iran. We used convenience sampling to conduct this cross-sectional study on 647 people living in cities under coverage in Kerman province, southern Iran. The data collection tool was a researcher-made questionnaire of vaccine symptoms and signs. The results were analyzed using ANOVA and Chi-squared tests by SPSS software (version 24). The mean age of the participants was 40.19±15.20. The results indicated that 431 people (66.6%) reported post-vaccination side effects, with 18.23% of them having severe side effects. We noticed the most severe side effects in AstraZeneca, Sinopharm, Sputnik, and Bharat. Fever, headache, and pain at the injection site were the most common side effects after vaccination in descending order, which had a statistically significant relationship with all types of vaccines (P=0.001). The side effects differed in the types of vaccines, and most of the vaccines had mild to moderate side effects. People with the B blood type showed the most severe side effects, while those with the AB showed the lowest rate of side effects. Therefore, the injection of the AstraZeneca vaccine in blood group B should be done with more caution. More attention should also be paid to blood groups B and A in the injection of COVID-19 vaccines. Moreover, health officials and the government should plan appropriate educational strategies to increase public awareness of the importance of vaccines in eradicating viral infections.

Resilient health systems for already resilient countries? Pandemic discourses in the post-COVID-19 era

This study aimed to reconstruct and analyze the discourses of the pandemic in the post-COVID-19 era. The methodology was based on a critical review of the scientific literature on the pandemic, selecting 80 non-biomedical, clinical, or pharmacological articles published in journals indexed in Scopus or Web of Science from a sample of the 500 most cited scientific articles on the pandemic in Google Scholar. The theoretical approach was based on the debates on predictability, unpredictability, determination, and indeterminacy in the health and social sciences. As a result, six theses on the pandemic were identified and analyzed: a) the thesis of the unpredictability of pandemics; b) the thesis of pandemic denial; c) the thesis of the pandemic as a failure in predictability systems; d) the thesis of the prevention of catastrophic events with timely interventions; e) the thesis of the structural postponement of predictive care by non-developed countries; and f) the environmentalist-health thesis, of foreseeing a critical phase for the planet and humanity. We concluded on the limits of resilience as the center in preparing Latin American health systems in the post-pandemic.

Genetic determination of regional connectivity in modelling the spread of COVID-19 outbreak for more efficient mitigation strategies

For the COVID-19 pandemic, viral transmission has been documented in many historical and geographical contexts. Nevertheless, few studies have explicitly modeled the spatiotemporal flow based on genetic sequences, to develop mitigation strategies. Additionally, thousands of SARS-CoV-2 genomes have been sequenced with associated records, potentially providing a rich source for such spatiotemporal analysis, an unprecedented amount during a single outbreak. Here, in a case study of seven states, we model the first wave of the outbreak by determining regional connectivity from phylogenetic sequence information (i.e. "genetic connectivity"), in addition to traditional epidemiologic and demographic parameters. Our study shows nearly all of the initial outbreak can be traced to a few lineages, rather than disconnected outbreaks, indicative of a mostly continuous initial viral flow. While the geographic distance from hotspots is initially important in the modeling, genetic connectivity becomes increasingly significant later in the first wave. Moreover, our model predicts that isolated local strategies (e.g. relying on herd immunity) can negatively impact neighboring regions, suggesting more efficient mitigation is possible with unified, cross-border interventions. Finally, our results suggest that a few targeted interventions based on connectivity can have an effect similar to that of an overall lockdown. They also suggest that while successful lockdowns are very effective in mitigating an outbreak, less disciplined lockdowns quickly decrease in effectiveness. Our study provides a framework for combining phylodynamic and computational methods to identify targeted interventions.

Estimation of real COVID-19 cases in India during the first wave

In 2020, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spread across the world within a few months. The SARS-CoV-2 pandemic has had a devastating effect on humanity, with social and economic consequences. The continents of Europe and America have been hit the hardest. However, there has also been a huge loss of life in India, with the country having the fourth highest number of total deaths worldwide. Nevertheless, the infection and death rates per million and the case fatality ratio in India are substantially lower than those in many developed nations. Several explanations for this have been proposed, including genetics. Mathematical modelling has suggested that the actual number of infections is much higher than the number of reported cases. Therefore, to understand the dynamics of actual infection and the population-level immunity against SARS-CoV-2, a serosurvey (antibody testing) was performed among 2301 individuals in urban regions of 14 districts in six states of India. A notable outcome of this study was that a large proportion of the Indian population had an asymptomatic SARS-CoV-2 infection. The real infection rate in India was several fold higher than the reported number of cases. Therefore, a large number of people in the country have developed SARS-CoV-2-specific antibodies. In this survey, the seroprevalence (frequency antibody-positive) varied between 0.01 (95% CI 0.002-0.054) and 0.477 (95% CI 0.392-0.563), suggesting a high variability in viral transmission between the states and the possibility of future waves. In this study population, the frequency of asymptomatic infection was highest in the younger age groups. It was also found that the numbers of cases reported by the government were several-fold lower than the real incidence of infection. It is likely that the high number of asymptomatic cases was the main driver of this discrepancy.

Trends in Confirmed COVID-19 Cases in the Korean Military Before and After the Emergence of the Omicron Variant

BACKGROUND

Due to the higher transmissibility and increased immune escape of the omicron variant of severe acute respiratory syndrome coronavirus 2, the number of patients with coronavirus disease 2019 (COVID-19) has skyrocketed in the Republic of Korea. Here, we analyzed the change in trend of the number of confirmed COVID-19 cases in the Korean military after the emergence of the omicron variant on December 5, 2021.

METHODS

An interrupted time-series analysis was performed of the daily number of newly confirmed COVID-19 cases in the Korean military from September 1, 2021 to April 10, 2022, before and after the emergence of the omicron variant. Moreover, the daily number of newly confirmed COVID-19 cases in the Korean military and in the population of Korean civilians adjusted to the same with military were compared.

RESULTS

The trends of COVID-19 occurrence in the military after emergence of the omicron variant was significantly increased (regression coefficient, 23.071; 95% confidence interval, 16.122-30.020; P < 0.001). The COVID-19 incidence rate in the Korean military was lower than that in the civilians, but after the emergence of the omicron variant, the increased incidence rate in the military followed that of the civilian population.

CONCLUSION

The outbreak of the omicron variant occurred in the Korean military despite maintaining high vaccination coverage and intensive non-pharmacological interventions.

Topic Evolution of Chinese COVID-19 Policies Based on Co-Occurrence Clustering Network Analysis

This study aims to explore the changes of Chinese coronavirus disease-2019 (COVID-19) policy topics in the eclipse, outbreak, and convalescent stage of COVID-19 based on 4982 textual policies. By using the co-occurrence clustering network method, we find that the strict prevention and control of the epidemic is the only topic of policies in the eclipse stage. In the outbreak stage, strict epidemic prevention and control is still the most important policy topic. The policies of resuming work of “essential” enterprises and stabilizing market prices are important support and guarantee for fighting against COVID-19. In the convalescent stage, as the prevention and control of COVID-19 has become regular, promoting and ensuring the resumption of work in all sectors of society is the most important topic of the policies. Moreover, the success of Wuhan City’s fight against COVID-19 reflects China’s governance characteristics of “concentrating power to do a major event”. Finally, the possible improvements for Chinese COVID-19 policies are discussed, which can provide practical suggestions for government departments on how to effectively respond to public health emergencies.

Estimating the cost of COVID-19 vaccine deployment and introduction in Ghana using the CVIC Tool

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Current COVID-19 vaccine supply market means LMICs will have to rely on a combination of different sources/types of vaccines to meet their demand.

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Deployment of COVID-19 vaccine plans in Ghana will cost $348.7–$436.1 million for coverage of 17.5 million of eligible Ghanaians.

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Vaccine cost constitute 78–83% of total cost whereas the total vaccination cost is 0.48–0.60% of the country’s 2020 GDP.

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The WHO-UNICEF CVIC tool is useful for comprehensive COVID-19 vaccine deployment costing and resource planning.

Background

This study estimated cost of COVID-19 vaccine introduction and deployment in Ghana.

Methods

Using the WHO-UNICEF COVID-19 Vaccine Introduction and deployment Costing (CVIC) tool Ghana’s Ministry of Health Technical Working Group for Health Technology Assessment (TWG-HTA) in collaboration with School of Public Health, University of Ghana, organized an initial two-day workshop that brought together partners to deliberate and agree on input parameters to populate the CVIC tool. A further 2–3 days validation with the Expanded Program of Immunization (EPI) and other partners to finalize the analysis was done. Three scenarios, with different combinations of vaccine products and delivery modalities, as well as time period were analyzed. The scenarios included AstraZeneca (40%), Johnson & Johnson (J&J) (30%), Moderna, Pfizer, and Sputnik V at 10% each; with primary schedule completed by second half of 2021 (Scenario 1); AstraZeneca (30%), J&J (40%), Moderna, Pfizer, and Sputnik V at 10% each with primary schedule completed by first half of 2022 (Scenario 2); and equal distribution (20%) among AstraZeneca, J&J, Moderna, Pfizer, and Sputnik V with primary schedule completed by second half of 2022 (Scenario 3).

Results

The estimated total cost of COVID-19 vaccination ranges between $348.7 and $436.1 million for the target population of 17.5 million. These translate into per person completed primary schedule cost of $20.9–$26.2 and per dose (including vaccine cost) of $10.5–$13.1. Again, per person completed primary schedule excluding vaccine cost was $4.5 and $4.6, thus per dose excluding vaccine also ranged from $2.2 – $2.3. The main cost driver was vaccine doses, including shipping, which accounts for between 78% and 83% of total cost. Further, an estimated 8,437–10,247 vaccinators (non-FTEs) would be required during 2021–2022 to vaccinate using a mix of delivery strategies, accounting for 8–10% of total cost.

Conclusion

These findings provide the estimates to inform resource mobilization efforts by government and other partners.

COVID-19 Passport as a Factor Determining the Success of National Vaccination Campaigns: Does It Work? The Case of Lithuania vs. Poland

As the ongoing COVID-19 pandemic poses a global threat, it is of utmost importance that governments should find effective means of combating vaccine hesitancy and encouraging their citizens to vaccinate. In our article, we compare the vaccination outcomes in the past months in two neighbouring post-communist EU states, Lithuania and Poland. Both introduced COVID-19 certificates, but only the former followed with gradual limitations for those who failed to get vaccinated, beginning with restricted access to restaurants, sports facilities and indoor events, and finally banning residents without a certificate from entering supermarkets or larger shops and using most services. By contrast, in Poland, the certificate remained a tool for international travel only. We show using statistical data that Lithuania’s strict policy, regardless of its social implications, led to markedly higher vaccination outcomes in all age groups than those in Poland at the time.

COVID-19 Vaccination: The Mainspring of Challenges and the Seed of Remonstrance

As of March 2020, the time when the coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) became a pandemic, our existence has been threatened and the lives of millions have been claimed. With this ongoing global issue, vaccines are considered of paramount importance in curtailing the outbreak and probably a prime gamble to bring us back to 'ordinary life'. To date, more than 200 vaccine candidates have been produced, many of which were approved by the Food and Drug Administration (FDA) for emergency use, with the research and discovery phase of their production process passed over. Capering such a chief practice in COVID-19 vaccine development, and manufacturing vaccines at an unprecedented speed brought many challenges into play and raised COVID-19 vaccine remonstrance. In this review, we highlight relevant challenges to global COVID-19 vaccine development, dissemination, and deployment, particularly at the level of large-scale production and distribution. We also delineate public perception on COVID-19 vaccination and outline the main facets affecting people's willingness to get vaccinated.

The COVID-19 Pandemic: A Health Crisis Managed or a Panic Response with Disastrous Future Consequences?

In 1 year, COVID-19 spread rapidly worldwide affecting all societies and most age-groups. It has taken not only a toll of human lives (approaching 220 million people infected with 4.55 million reported deaths at time of writing) but also decimated every economy as countries struggle to control infection rates by introducing draconian lockdown and social distancing measures, bringing great suffering well beyond medical effects of the disease. A parallel pandemic has resulted in a deluge of information emanating from both scientific as well as international news media including social media platforms. Fact and fiction, reality, and perception have become entangled; the only realistic solution, both medically as well as politically, is concerted global vaccination (which is currently underway) to reduce further infection by introducing universal immunity. However, public controversy rages due to widespread apprehension regarding necessity, immediate risks, and long-term safety of what is perceived as "fast-tracked" medication. While some concerns may be justified, much is due to misconception and misunderstanding. This review highlights some of the issues concerning the handling of the COVID-19 crisis by governments worldwide, the medical and scientific communities, and the media and how this may have laid the foundations for a far greater medical, social, and economic burden in the coming years. We present comparative data to challenge current conceptions of this disease in the more general context of human health to provide a perspective that seems to have been lost in the general panic. We need more rational approaches to the handling of a disease which is unlikely to disappear from our spectrum of afflictions even after the magnifying glass has been removed.

COVID-19 Vaccine Platforms: Challenges and Safety Contemplations

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a pandemic as of March 2020, creating a global crisis and claiming millions of lives. To halt the pandemic and alleviate its impact on society, economy, and public health, the development of vaccines and antiviral agents against SARS-CoV-2 was a dire need. To date, various platforms have been utilized for SARS-CoV-2 vaccine development, and over 200 vaccine candidates have been produced, many of which have obtained the United States Food and Drug Administration (FDA) approval for emergency use. Despite this successful development and licensure, concerns regarding the safety and efficacy of these vaccines have arisen, given the unprecedented speed of vaccine development and the newly emerging SARS-CoV-2 strains and variants. In this review, we summarize the different platforms used for Coronavirus Disease 2019 (COVID-19) vaccine development, discuss their strengths and limitations, and highlight the major safety concerns and potential risks associated with each vaccine type.

Intranasal Vaccination Strategy to Control the COVID-19 Pandemic from a Veterinary Medicine Perspective

Simple Summary

Intranasal vaccination is one of the methods used to stimulate mucosal immunity. It has been widely practised to control many human and animal respiratory diseases. Coronavirus disease 2019 (COVID-19) is a highly contagious respiratory disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which resulted in a global pandemic. COVID-19 has reminded some veterinarians of various contagious veterinary diseases, including coronavirus infections in animals. This article discusses the control of highly contagious diseases of veterinary importance with emphasis on an intranasal vaccination approach, and the potential of implementing similar strategies in human medicine to control the ongoing COVID-19 pandemic.

Abstract

The world is currently facing an ongoing coronavirus disease 2019 (COVID-19) pandemic. The disease is a highly contagious respiratory disease which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Current control measures used by many countries include social distancing, wearing face masks, frequent hand washing, self-isolation, and vaccination. The current commercially available vaccines are injectable vaccines, although a few intranasal vaccines are in trial stages. The reported side effects of COVID-19 vaccines, perceptions towards the safety of the vaccines, and frequent mutation of the virus may lead to poor herd immunity. In veterinary medicine, attaining herd immunity is one of the main considerations in disease control, and herd immunity depends on the use of efficacious vaccines and the vaccination coverage in a population. Hence, many aerosol or intranasal vaccines have been developed to control veterinary respiratory diseases such as Newcastle disease, rinderpest, infectious bronchitis, and haemorrhagic septicaemia. Different vaccine technologies could be employed to improve vaccination coverage, including the usage of an intranasal live recombinant vaccine or live mutant vaccine. This paper discusses the potential use of intranasal vaccination strategies against human COVID-19, based on a veterinary intranasal vaccine strategy.

New strategy to control covid-19 pandemic using lead/lag compensator

COVID-19 is still the main worldwide issue since the outbreak. Many strategies were implemented such as suppression, mitigation, and mathematical-engineering strategies, to control this pandemic. In this work, a lead/lag compensator is proposed to control an unstable Covid-19 nonlinear system after using some required assumptions. The control theory is involved with the unstable pandemic and other existing strategies until the invention of the vaccine is approved. In addition, the Most Valuable Player Algorithm (MVPA) is used to optimize the parameters of the proposed controller and to determine whether it is a lead or lag compensator. Finally, the simulation results are based on the daily reports of two pandemic cities: Hubei (China), and Lazio (Italy) since the outbreak began. It can be concluded that the lead/lag compensator can effectively control the COVID-19 system.

The main strategies adopted by the Toronto government in the COVID-19 pandemic: epidemiology study

Objetive To analyze the epidemiological data and the main government measures adopted against the COVID-19 pandemic. Methods Epidemiologic study built with data from the integrated Public Health Information System (iPHIS) and the official Government of Canada website in a time frame from January to July 2020. Results Toronto presents the first case of COVID 19 on January 23rd and until July 1st, 2020, it records a number of 14 468 cases, 12.574 recovered cases, 1.100 deaths and 171 institutional outbreaks. About 53,04% of the cases were female, aged 40-59 years (29,81%), followed by 20-39 years (28,37%). Contagion forms were analyzed: 56,40% had close contact with a case, 24,23% in the community, 10,30% in health services, 5,58% while traveling and 3,49% in institutions. Economic and financial actions, travel measures, support for Canadians abroad, public education, research and technology were developed. Conclusion The COVID-19 is a serious threat to public health around the world. Canada has a strong history of pandemic planning and has worked together with public health for its developed actions to become adaptable based on evolution, outbreak containment and prevention of further spread.

COVID-19 pandemic management and the rheumatology patient

We discuss the evidence behind mask use, including evidence for homemade masks, social distancing, and the local coronavirus disease-2019 (COVID-19) epidemics in countries that initially employed more limited public health interventions. Given the absence of data for specific interventions in the rheumatic disease population, we reviewed the evidence available for the general population. The risk of poor outcomes with COVID-19 in patients with rheumatic diseases is a potential concern given the immunosuppression associated with these conditions and disease-modifying anti-rheumatic drug therapy, as well as advancing age and many of the comorbidities present in such patients. Infection prevention is key, for both individual patients and their community. Given the data collected from the general population, we recommend ongoing proper mask use, social distancing, and hand hygiene for patients with rheumatic diseases and encourage providers to counsel these patients in prevention strategies and attempt to dispel abundant misinformation.

The COVID-19 pandemic through eyes of a NYC fertility center: a unique learning experience with often unexpected results

Affecting basic tenets of human existence such as health, economic as well as personal security and, of course, reproduction, the COVID-19 pandemic transcended medical specialties and professional disciplines. Yet, six months into the pandemic, there still exists no consensus on how to combat the virus in absence of a vaccine. Facing unprecedented circumstances, and in absence of real evidence on how to proceed, our organization early in the pandemic decided to act independently from often seemingly irrational guidance and, instead, to carefully follow a quickly evolving COVID-19 literature. Here described is the, likely, unique journey of a fertility center that maintained services during peaks of COVID-19 and political unrest that followed. Closely following publicly available data, we recognized relatively early that New York City and other East Coast regions, which during the initial COVID-19 wave between March and May represented the hardest-hit areas in the country, during the second wave, beginning in June and still in progress, remained almost completely unaffected. In contrast, south western regions, almost completely unaffected by the initial wave, were severely affected in the second wave. These two distinctively different infectious phenotypes suggested two likely explanations: The country was witnessing infections with two different SARS-CoV-2 viruses and NYC (along with the East Coast) acquired during the first wave much better immunity to the virus than south western regions. Both hypotheses since have been confirmed: East and West Coasts, indeed, were initially infected by two distinctively different lineages of the virus, with the East Coast lineage being 10-times more infectious. In addition, immunologists discovered an up to this point unknown long-term anti-viral innate (cellular) immune response which offers additional and much broader anti-viral immunity than the classical adaptive immunity via immobilizing antibodies that has been known for decades. Consequently, we predict that in the U.S., even in absence of an available vaccine, COVID-19, by September-October, will be at similarly low levels as are currently seen in NYC and other East Coast regions (generally < 1% test-positivity). We, furthermore, predict that, if current mitigation measures are maintained and no newly aggressive mutation of the virus enters the country, a significant fall-wave of COVID-19, in combination with the usual fall wave of influenza, appears unlikely. To continue serving patients uninterrupted throughout the pandemic, turned for all of our center's staff into a highly rewarding experience, garnered respect and appreciation from patients, and turned into an absolutely unique learning experience.

A Review of the Progress and Challenges of Developing a Vaccine for COVID-19

A novel coronavirus, which has been designated as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), was first detected in December 2019 in Wuhan China and causes the highly infectious disease referred to as COVID-19. COVID-19 has now spread worldwide to become a global pandemic affecting over 24 million people as of August 26th, 2020 and claimed the life of more than 800,000 people worldwide. COVID-19 is asymptomatic for some individuals and for others it can cause symptoms ranging from flu-like to acute respiratory distress syndrome (ARDS), pneumonia and death. Although it is anticipated that an effective vaccine will be available to protect against COVID-19, at present the world is relying on social distancing and hygiene measures and repurposed drugs. There is a worldwide effort to develop an effective vaccine against SARS-CoV-2 and, as of late August 2020, there are 30 vaccines in clinical trials with over 200 in various stages of development. This review will focus on the eight vaccine candidates that entered Phase 1 clinical trials in mid-May, including AstraZeneca/Oxford's AZD1222, Moderna's mRNA-1273 and Sinovac's CoronaVac vaccines, which are currently in advanced stages of vaccine development. In addition to reviewing the different stages of vaccine development, vaccine platforms and vaccine candidates, this review also discusses the biological and immunological basis required of a SARS-CoV-2 vaccine, the importance of a collaborative international effort, the ethical implications of vaccine development, the efficacy needed for an immunogenic vaccine, vaccine coverage, the potential limitations and challenges of vaccine development. Although the demand for a vaccine far surpasses the production capacity, it will be beneficial to have a limited number of vaccines available for the more vulnerable population by the end of 2020 and for the rest of the global population by the end of 2021.

A Minimalist Strategy Towards Temporarily Defining Protection for COVID-19

Until either efficacious therapy or vaccination for COVID-19 is achieved, there will be a need to regain world economic stability while yet controlling the pandemic with current approaches. For those infected thus far, there is a prevailing perspective that devising recognition for protective immunity will progressively allow segments of society to return to some functionality more than is existing. At this time, the best correlates with protection from natural coronavirus infections are systemic neutralizing antibody and mucosal IgA. Serum neutralizing antibody more easily fulfills the latter requisite, but current live virus methods for neutralization prevent large-scale application. It is conceivable that the exposure of previously infected individuals can allow for the definition of protective thresholds of neutralizing antibody. Thereafter, many other antibody assays will be able to screen for surrogate protection after correlations with protective neutralizing antibody are made. Specificity of common antibody tests would benefit from confirmatory blocking systems or confirmatory immunoblotting fingerprints with well-defined antigen(s). The opportunity for the scientific community to make these assessments is evident in the current context of the COVID-19 epidemic given the large numbers of infected individuals worldwide. Such information will also be vital to guide vaccine development and/or immunotherapy.

Coronavirus herd immunity optimizer (CHIO)

In this paper, a new nature-inspired human-based optimization algorithm is proposed which is called coronavirus herd immunity optimizer (CHIO). The inspiration of CHIO is originated from the herd immunity concept as a way to tackle coronavirus pandemic (COVID-19). The speed of spreading coronavirus infection depends on how the infected individuals directly contact with other society members. In order to protect other members of society from the disease, social distancing is suggested by health experts. Herd immunity is a state the population reaches when most of the population is immune which results in the prevention of disease transmission. These concepts are modeled in terms of optimization concepts. CHIO mimics the herd immunity strategy as well as the social distancing concepts. Three types of individual cases are utilized for herd immunity: susceptible, infected, and immuned. This is to determine how the newly generated solution updates its genes with social distancing strategies. CHIO is evaluated using 23 well-known benchmark functions. Initially, the sensitivity of CHIO to its parameters is studied. Thereafter, the comparative evaluation against seven state-of-the-art methods is conducted. The comparative analysis verifies that CHIO is able to yield very competitive results compared to those obtained by other well-established methods. For more validations, three real-world engineering optimization problems extracted from IEEE-CEC 2011 are used. Again, CHIO is proved to be efficient. In conclusion, CHIO is a very powerful optimization algorithm that can be used to tackle many optimization problems across a wide variety of optimization domains.