Herd Immunity: A Success or a Failure

2020 ◽  
Vol 2 (1) ◽  
Keyword(s):  
Herd Immunity

ADDRESSING THE ISSUE OF СOVID-19, SARS-COV-2 VIRUS AND THE DISEASE

2020 ◽  
Vol 99 (6) ◽  
pp. 15-31
Author(s):  
A.A. Korenkova ◽  
◽  
E.M. Mayorova ◽  
V.V. Bahmetjev ◽  
M.V. Tretyak ◽  
...  
Keyword(s):  
Public Health ◽  
Immune Responses ◽  
Molecular Mechanisms ◽  
Herd Immunity ◽  
Significant Problem ◽  
Prevention Measures ◽  
Optimal Therapy ◽  
The World ◽  
Public Health Challenge ◽  
Coronavirus Infection

The new coronavirus infection has posed a major public health challenge around the world, but new data on the disease raises more questions than answers. The lack of optimal therapy is a significant problem. The article examines the molecular mechanisms of SARS-CoV-2 infection and the pathogenesis of COVID-19, special attention is paid to features of pathological processes and immune responses in children. COVID-19 leads to a wide diversity of negative outcomes, many of which can persist for at least months. Many of the consequences have yet to be identified. SARS-CoV-2 may provoke autoimmune reactions. Reinfection, herd immunity, vaccines and other prevention measures are also discussed in this review.

The Prospect of Herd Immunity to Curb COVID-19 in Bangladesh: A Review

2020 ◽  
Author(s):  
Onamika Rani Sarker ◽  
Sabyasachi Antor Chanda
Keyword(s):  
Herd Immunity

SARS-CoV-2 Seroprevalence Study in Pimpri-Chinchwad, Maharashtra, India Coinciding with Falling Trend – Do the Results Suggest Imminent Herd Immunity?

2020 ◽  
Author(s):  
Amitav Banerjee ◽  
Bhargav Gaikwad ◽  
Atul Desale ◽  
Sudhir L. Jadhav ◽  
Jitendra Bhawalkar ◽  
...  
Keyword(s):  
Herd Immunity ◽  
Seroprevalence Study

Can Mandated BCG Vaccine Promote herd Immunity against Novel Coronavirus? A Potential Solution at Hand to Tackle Covid-19 Pandemic

2020 ◽  
Vol 16 (1) ◽  
pp. 6-11
Author(s):  
Ashok Arasu ◽  
Pavithra Balakrishnan ◽  
Thirunavukkarasu Velusamy ◽  
Thiagarajan Ramesh
Keyword(s):  
Protective Factor ◽  
Herd Immunity ◽  
Bcg Vaccine ◽  
Intestinal Cells ◽  
Global Public Health ◽  
Wuhan City ◽  
Live Attenuated Vaccine ◽  
Angiotensin Converting Enzyme 2 ◽  
Lung Epithelial ◽  
Novel Coronavirus

The 2019 novel coronavirus (2019-nCoV) infection is an emerging pandemic that poses a severe threat to global public health. This pandemic started from the Wuhan City of Hubei Province in China, and is speculated to have originated from bats and spread among humans with an unknown intermediate transmitter. The virus binds to angiotensin-converting enzyme 2 (ACE2), which is abundantly expressed on various human cells, including lung epithelial and intestinal cells, thereby entering into these cells and causing infection. It is transmitted to other humans through airborne droplets from infected patients. Presently there are no specific treatments or vaccines that are available to curtail the spread of this disease. There are few indirect reports that explain the potential importance of the mandated BCG vaccine as a protective factor against COVID-19. There is a speculation that a live attenuated vaccine (BCG vaccine) can be beneficial against COVID-19 to develop the initial immune response, and can also spread in the community, thereby boosting herd immunity to fight against COVID-19. This review summarizes the conclusions of various reports on the BCG vaccine, and is an attempt to establish BCG-vaccination mediated herd immunity as an effective instant intermediate approach in curbing COVID-19 spread in highly populous countries.

SARS-CoV-2 Biology Insights, Part IV.Antibody-Dependent Enhancement (ADE) and the tricky “Herd Immunity”: narrative review (Preprint)

2020 ◽  
Author(s):  
Laura Lafon-Hughes
Keyword(s):  
Viral Infection ◽  
Viral Entry ◽  
Neutralizing Antibodies ◽  
Vaccine Development ◽  
Whooping Cough ◽  
Common Knowledge ◽  
Herd Immunity ◽  
Life Quality ◽  
Host Cells ◽  
System P

BACKGROUND It is common knowledge that vaccination has improved our life quality and expectancy since it succeeded in achieving almost eradication of several diseases including chickenpox (varicella), diphtheria, hepatitis A and B, measles, meningococcal, mumps, pneumococcal, polio, rotavirus, rubella, tetanus and whooping cough (pertussis) Vaccination success is based on vaccine induction of neutralizing antibodies that help fight the infection (e.g. by a virus), preventing the disease. Conversely, Antibody-dependent enhancement (ADE) of a viral infection occurs when anti-viral antibodies facilitate viral entry into host cells and enhance viral infection in these cells. ADE has been previously studied in Dengue and HIV viruses and explains why a second infection with Dengue can be lethal. As already reviewed in Part I and Part II, SARS-Cov-2 shares with HIV not only 4 sequences in the Spike protein but also the capacity to attack the immune system. OBJECTIVE As HIV presents ADE, we wondered whether this was also the case regarding SARS-CoV-2. METHODS A literature review was done through Google. RESULTS SARS-CoV-2 presents ADE. As SARS, which does not have the 4 HIV-like inserts, has the same property, ADE would not be driven by the HIV-like spike sequences. CONCLUSIONS ADE can explain the failure of herd immunity-based strategies and will also probably hamper anti-SARS-CoV-2 vaccine development. As reviewed in Part I, there fortunately are promising therapeutic strategies for COVID-19, which should be further developed. In the meantime, complementary countermeasures to protect mainly the youth from this infection are presented to be discussed in Part V Viewpoint.

scholarly journals COVID-19 Vaccine Intention among Healthcare Workers in Saudi Arabia: A Cross-Sectional Survey

Vaccines ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 835
Author(s):  
Mohammed Noushad ◽  
Mohammad Zakaria Nassani ◽  
Anas B. Alsalhani ◽  
Pradeep Koppolu ◽  
Fayez Hussain Niazi ◽  
...  
Keyword(s):  
Saudi Arabia ◽  
Healthcare System ◽  
Healthcare Workers ◽  
Vaccine Coverage ◽  
Vaccination Campaign ◽  
Herd Immunity ◽  
Positive Sign ◽  
Cross Sectional Survey ◽  
Cross Sectional ◽  
Public Health Strategies

The COVID-19 pandemic has caused largescale morbidity and mortality and a tremendous burden on the healthcare system. Healthcare workers (HCWs) require adequate protection to avoid onward transmission and minimize burden on the healthcare system. Moreover, HCWs can also influence the general public into accepting the COVID-19 vaccine. Therefore, determining COVID-19 vaccine intention among HCWs is of paramount importance to plan tailor-made public health strategies to maximize vaccine coverage. A structured questionnaire was administered in February and March 2021 among HCWs in Saudi Arabia using convenience sampling, proceeding the launch of the vaccination campaign. HCWs from all administrative regions of Saudi Arabia were included in the study. In total, 674 out of 1124 HCWs responded and completed the survey (response rate 59.9%). About 65 percent of the HCWs intended to get vaccinated. The intention to vaccinate was significantly higher among HCWs 50 years of age or older, Saudi nationals and those who followed the updates about COVID-19 vaccines (p < 0.05). The high percentage (26 percent) of those who were undecided in getting vaccinated is a positive sign. As the vaccination campaign gathers pace, the attitude is expected to change over time. Emphasis should be on planning healthcare strategies to convince the undecided HCWs into accepting the vaccine in order to achieve the coverage required to achieve herd immunity.

scholarly journals Are We Paving the Way to Dig Out of the “Pandemic Hole”? A Narrative Review on SARS-CoV-2 Vaccination: From Animal Models to Human Immunization

2021 ◽  
Vol 9 (3) ◽  
pp. 53
Author(s):  
Giuseppe Tardiolo ◽  
Pina Brianti ◽  
Daniela Sapienza ◽  
Pia dell’Utri ◽  
Viviane Di Dio ◽  
...  
Keyword(s):  
Animal Models ◽  
Viral Vector ◽  
Herd Immunity ◽  
Population Level ◽  
Narrative Review ◽  
Therapeutic Interventions ◽  
Preclinical Research ◽  
Inactivated Vaccines ◽  
Preclinical And Clinical Studies ◽  
Social Upheaval

The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is a new pathogen agent causing the coronavirus infectious disease (COVID-19). This novel virus originated the most challenging pandemic in this century, causing economic and social upheaval internationally. The extreme infectiousness and high mortality rates incentivized the development of vaccines to control this pandemic to prevent further morbidity and mortality. This international scenario led academic scientists, industries, and governments to work and collaborate strongly to make a portfolio of vaccines available at an unprecedented pace. Indeed, the robust collaboration between public systems and private companies led to resolutive actions for accelerating therapeutic interventions and vaccines mechanism. These strategies contributed to rapidly identifying safe and effective vaccines as quickly and efficiently as possible. Preclinical research employed animal models to develop vaccines that induce protective and long-lived immune responses. A spectrum of vaccines is worldwide under investigation in various preclinical and clinical studies to develop both individual protection and safe development of population-level herd immunity. Companies employed and developed different technological approaches for vaccines production, including inactivated vaccines, live-attenuated, non-replicating viral vector vaccines, as well as acid nucleic-based vaccines. In this view, the present narrative review provides an overview of current vaccination strategies, taking into account both preclinical studies and clinical trials in humans. Furthermore, to better understand immunization, animal models on SARS-CoV-2 pathogenesis are also briefly discussed.

scholarly journals Estimating asymptomatic, undetected and total cases for the COVID-19 outbreak in Wuhan: a mathematical modeling study

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Xi Huo ◽  
Jing Chen ◽  
Shigui Ruan
Keyword(s):  
Disease Transmission ◽  
Large Scale ◽  
Transmission Rate ◽  
Control Strategies ◽  
Herd Immunity ◽  
Antibody Prevalence ◽  
Screening Process ◽  
Vaccination Programs ◽  
Prevalence Level ◽  
The Impact

Abstract Background The COVID-19 outbreak in Wuhan started in December 2019 and was under control by the end of March 2020 with a total of 50,006 confirmed cases by the implementation of a series of nonpharmaceutical interventions (NPIs) including unprecedented lockdown of the city. This study analyzes the complete outbreak data from Wuhan, assesses the impact of these public health interventions, and estimates the asymptomatic, undetected and total cases for the COVID-19 outbreak in Wuhan. Methods By taking different stages of the outbreak into account, we developed a time-dependent compartmental model to describe the dynamics of disease transmission and case detection and reporting. Model coefficients were parameterized by using the reported cases and following key events and escalated control strategies. Then the model was used to calibrate the complete outbreak data by using the Monte Carlo Markov Chain (MCMC) method. Finally we used the model to estimate asymptomatic and undetected cases and approximate the overall antibody prevalence level. Results We found that the transmission rate between Jan 24 and Feb 1, 2020, was twice as large as that before the lockdown on Jan 23 and 67.6% (95% CI [0.584,0.759]) of detectable infections occurred during this period. Based on the reported estimates that around 20% of infections were asymptomatic and their transmission ability was about 70% of symptomatic ones, we estimated that there were about 14,448 asymptomatic and undetected cases (95% CI [12,364,23,254]), which yields an estimate of a total of 64,454 infected cases (95% CI [62,370,73,260]), and the overall antibody prevalence level in the population of Wuhan was 0.745% (95% CI [0.693%,0.814%]) by March 31, 2020. Conclusions We conclude that the control of the COVID-19 outbreak in Wuhan was achieved via the enforcement of a combination of multiple NPIs: the lockdown on Jan 23, the stay-at-home order on Feb 2, the massive isolation of all symptomatic individuals via newly constructed special shelter hospitals on Feb 6, and the large scale screening process on Feb 18. Our results indicate that the population in Wuhan is far away from establishing herd immunity and provide insights for other affected countries and regions in designing control strategies and planing vaccination programs.

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