Assessing the risk of vaccine-driven virulence evolution in SARS-CoV-2

The evolution of SARS-CoV-2 virulence, or lethality, threatens to exacerbate the burden of COVID-19 on society. How might COVID-19 vaccines alter selection for increased SARS-CoV-2 virulence? Framing current evidence surrounding SARS-CoV-2 biology and COVID-19 vaccines in the context of evolutionary theory indicates that prospects for virulence evolution remain uncertain. However, differential effects of vaccinal immunity on transmission and disease severity between respiratory compartments could select for increased virulence. To bound expectations for this outcome, we analyse an evo-epidemiological model. Synthesizing model predictions with vaccine efficacy data, we conclude that while vaccine-driven virulence remains a theoretical possibility, the risk is low if vaccines provide sustained robust protection against infection. Furthermore, we found that any increases in transmission concomitant with increases in virulence would be unlikely to threaten prospects for herd immunity in a highly immunized population. Given that virulence evolution would nevertheless impact unvaccinated individuals and populations with low vaccination rates, it is important to achieve high vaccination rates worldwide and ensure that vaccinal immunity provides robust protection against both infection and disease, potentially through the use of booster doses.

Download Full-text

No current evidence for risk of vaccine-driven virulence evolution in SARS-CoV-2

10.1101/2020.12.01.20241836 ◽

2020 ◽

Cited By ~ 1

Author(s):

Ian F. Miller ◽

C. Jessica E. Metcalf

Keyword(s):

Respiratory Tract ◽

Positive Association ◽

Preliminary Evidence ◽

Clinical Severity ◽

Current Evidence ◽

Upper Respiratory Tract ◽

Virulence Evolution ◽

Upper Respiratory ◽

Selection For ◽

Second Wave

AbstractVaccines that reduce clinical severity but not infection or transmission could drive the evolution of increased rates of pathogen-inflicted damage, or virulence. Preliminary evidence suggests that COVID-19 vaccines might have such differential effects, conferring greater protection in the lower respiratory tract, where viral growth most impacts severity, than in the upper respiratory tract, where infection is chiefly determined. However, the evolution of increased virulence can only occur under certain conditions, which include the existence of a positive association between transmission and severity linked to viral genetic variation. Here, we review the current evidence for these conditions, which does not point to a risk of vaccine driven virulence evolution. An evo-epidemiological model also indicates that upper respiratory tract protection can minimize or negate selection for increased virulence should these conditions be met. Despite low apparent risks, SARS-CoV-2 virulence should be monitored, and transmission-limiting characteristics should be prioritized for ‘second-wave’ vaccines.

Download Full-text

The Effect of Vaccination Rates on the Infection of COVID-19 under the Vaccination Rate below the Herd Immunity Threshold

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18147491 ◽

2021 ◽

Vol 18 (14) ◽

pp. 7491

Author(s):

Yi-Tui Chen

Keyword(s):

Infection Rate ◽

Herd Immunity ◽

The United States ◽

Vaccination Rate ◽

Infection Rates ◽

Vaccination Rates ◽

The United Kingdom ◽

The World ◽

Almost All ◽

The Impact

Although vaccination is carried out worldwide, the vaccination rate varies greatly. As of 24 May 2021, in some countries, the proportion of the population fully vaccinated against COVID-19 has exceeded 50%, but in many countries, this proportion is still very low, less than 1%. This article aims to explore the impact of vaccination on the spread of the COVID-19 pandemic. As the herd immunity of almost all countries in the world has not been reached, several countries were selected as sample cases by employing the following criteria: more than 60 vaccine doses per 100 people and a population of more than one million people. In the end, a total of eight countries/regions were selected, including Israel, the UAE, Chile, the United Kingdom, the United States, Hungary, and Qatar. The results find that vaccination has a major impact on reducing infection rates in all countries. However, the infection rate after vaccination showed two trends. One is an inverted U-shaped trend, and the other is an L-shaped trend. For those countries with an inverted U-shaped trend, the infection rate begins to decline when the vaccination rate reaches 1.46–50.91 doses per 100 people.

Download Full-text

COVID-19 Vaccination Rates by Global Universal Health Care Coverage Status

International Journal of Translational Medical Research and Public Health ◽

10.21106/ijtmrph.328 ◽

2021 ◽

Vol 5 (1) ◽

pp. 33-36

Author(s):

Deepa Dongarwar ◽

Hamisu M. Salihu

Keyword(s):

Health Care ◽

Herd Immunity ◽

Vaccination Rate ◽

Universal Health Care ◽

Vaccination Rates ◽

Creative Commons ◽

Universal Health Care Coverage ◽

Universal Health ◽

Open Access Article ◽

Better Than

Healthcare coverage and the type of insurance have always played huge roles in public health outcomes. With coronavirus disease-2019 (COVID-19) vaccination now available across the world, we sought to determine vaccination rates across countries with Universal Health Care (UHC) coverage versus those without. We utilized the vaccination information from the Coronavirus (COVID-19) Vaccinations website, and calculated early vaccination rate for each country as of January, 13, 2021 by dividing the total number of vaccinations given to the total population of the country. We observed that the average early vaccination rate for countries with UHC was 1.55%, whereas that for countries without UHC was 0.51%. Countries with UHC are performing much better than those without UHC in this initial race for providing herd immunity across the globe. Copyright © 2021 Dongarwar and Salihu. Published by Global Health and Education Projects, Inc. This is an open-access article distributed under the terms of the Creative Commons Attribution License CC BY 4.0.

Download Full-text

Demographics, perceptions, and socioeconomic factors affecting influenza vaccination among adults in the United States

PeerJ ◽

10.7717/peerj.5171 ◽

2018 ◽

Vol 6 ◽

pp. e5171 ◽

Cited By ~ 17

Author(s):

Kaja M. Abbas ◽

Gloria J. Kang ◽

Daniel Chen ◽

Stephen R. Werre ◽

Achla Marathe

Keyword(s):

United States ◽

Health Insurance ◽

Influenza Vaccination ◽

Vaccine Efficacy ◽

Herd Immunity ◽

The United States ◽

Vaccine Cost ◽

Factors Affecting ◽

Vaccination Rates ◽

Healthy People 2020

Objective The study objective is to analyze influenza vaccination status by demographic factors, perceived vaccine efficacy, social influence, herd immunity, vaccine cost, health insurance status, and barriers to influenza vaccination among adults 18 years and older in the United States. Background Influenza vaccination coverage among adults 18 years and older was 41% during 2010–2011 and has increased and plateaued at 43% during 2016–2017. This is below the target of 70% influenza vaccination coverage among adults, which is an objective of the Healthy People 2020 initiative. Methods We conducted a survey of a nationally representative sample of adults 18 years and older in the United States on factors affecting influenza vaccination. We conducted bivariate analysis using Rao-Scott chi-square test and multivariate analysis using weighted multinomial logistic regression of this survey data to determine the effect of demographics, perceived vaccine efficacy, social influence, herd immunity, vaccine cost, health insurance, and barriers associated with influenza vaccination uptake among adults in the United States. Results Influenza vaccination rates are relatively high among adults in older age groups (73.3% among 75 + year old), adults with education levels of bachelor’s degree or higher (45.1%), non-Hispanic Whites (41.8%), adults with higher incomes (52.8% among adults with income of over $150,000), partnered adults (43.2%), non-working adults (46.2%), and adults with internet access (39.9%). Influenza vaccine is taken every year by 76% of adults who perceive that the vaccine is very effective, 64.2% of adults who are socially influenced by others, and 41.8% of adults with health insurance, while 72.3% of adults without health insurance never get vaccinated. Facilitators for adults getting vaccinated every year in comparison to only some years include older age, perception of high vaccine effectiveness, higher income and no out-of-pocket payments. Barriers for adults never getting vaccinated in comparison to only some years include lack of health insurance, disliking of shots, perception of low vaccine effectiveness, low perception of risk for influenza infection, and perception of risky side effects. Conclusion Influenza vaccination rates among adults in the United States can be improved towards the Healthy People 2020 target of 70% by increasing awareness of the safety, efficacy and need for influenza vaccination, leveraging the practices and principles of commercial and social marketing to improve vaccine trust, confidence and acceptance, and lowering out-of-pocket expenses and covering influenza vaccination costs through health insurance.

Download Full-text

Vaccination Against COVID-19: Emerging Issues and Future Prospects

Annals of the Russian academy of medical sciences ◽

10.15690/vramn1672 ◽

2021 ◽

Vol 76 (6) ◽

pp. 652-660

Author(s):

Gennadiy G. Onischenko ◽

Tatiana E. Sizikova ◽

Vitaliy N. Lebedev ◽

Sergey V. Borisevich

Keyword(s):

Effective Means ◽

Herd Immunity ◽

High Rate ◽

Vaccination Rates ◽

Actual Duration ◽

Entire Duration ◽

Mass Immunization ◽

Emerging Issues ◽

First Time

The most effective means of combating the COVID-19 pandemic s the formation of herd immunity, with the formation of an immune population to infection. Vaccination rates are continuously increasing. In early February 2021, WHO announced that the number of people vaccinated against the disease for the first time exceeded the number of infected. In early June 2021 the vaccinated number exceeded 2 billion which is more than 12 times the total number infected for the entire duration of the pandemic. The high rate of vaccination leads to the formulation of a number of questions concerning the effectiveness of vaccines currently used for mass immunization the level of herd immunity, necessary to stop the spread of the disease, the actual duration of the vaccination carried out, long-term prospects of the platforms, used in the creation of vaccines. The purpose of this paper is to substantiate reasoned answers to the questions posed.

Download Full-text

Investors and Exploiters in Ecology and Economics

10.7551/mitpress/9780262036122.001.0001 ◽

2018 ◽

Keyword(s):

Social Sciences ◽

Evolutionary Theory ◽

Herd Immunity ◽

Natural World ◽

The Other ◽

Independent Research ◽

Research Traditions ◽

The Social ◽

Widespread Phenomenon ◽

Cancerous Cells

In the natural world, some agents (investors) employ strategies that provide resources, services, or information while others (exploiters) achieve gain through these efforts. Such behavior coexists and is observable in many species at many levels: from bacteria which depend on the existence of biofilms to synthesize constituent proteins; to cancerous cells which employ angiogenesis in tumors; to parents who forego vaccinating their children yet benefit from herd immunity; to countries’ actions in the handling of greenhouse gases. To analyze such behavior, two independent research traditions have developed in parallel—one couched in evolutionary theory championed by behavioral ecologists, the other in the social sciences advocated by economists. This book looks for commonalities in understanding and approach, in an effort to spur research into this widespread phenomenon.

Download Full-text

Getting personal: how vaccination exemptions shape herd immunity

10.1101/500553 ◽

2018 ◽

Author(s):

Emma R Nedell ◽

Romain Garnier ◽

Saad B Omer ◽

Shweta Bansal

Keyword(s):

Policy Change ◽

Spatial Clustering ◽

Vaccine Coverage ◽

Herd Immunity ◽

The United States ◽

Vaccine Preventable Diseases ◽

Vaccination Rates ◽

Before And After ◽

Exemption Policy ◽

Epidemiological Effects

Background: State-mandated school entry immunization requirements in the United States play an important role in achieving high vaccine coverage and preventing outbreaks of vaccine-preventable diseases. Most states allow non-medical exemptions that let children remain unvaccinated on the basis of personal beliefs. However, the ease of obtaining such exemptions varies, resulting in a patchwork of state vaccination exemption laws, contributing to heterogeneity in vaccine coverage across the country. In this study, we evaluate epidemiological effects and spatial variations in non-medical exemption rates in the context of vaccine policies. Methods and Findings: We first analyzed the correlation between non-medical exemption rates and vaccine coverage for three significant childhood vaccinations and found that higher rates of non-medical exemptions were associated with lower vaccination rates of school-aged children in all cases. We then identified a subset of states where exemption policy has recently changed and found that the effects on statewide non-medical exemption rates varied widely. Focusing further on Vermont and California, we illustrated how the decrease in non-medical exemptions due to policy change was concurrent to an increase in medical exemptions (in CA) or religious exemptions (in VT). Finally, a spatial clustering analysis was performed for Connecticut, Illinois, and California, identifying clusters of high non-medical exemption rates in these states before and after a policy change occurred. The clustering analyses show that policy changes affect spatial distribution of non-medical exemptions within a state. Conclusions: Our work suggests that vaccination policies have significant impacts on patterns of herd immunity. Our findings can be used to develop evidence-based vaccine legislation.

Download Full-text

Phage Therapy for Multi-Drug Resistant Respiratory Tract Infections

Viruses ◽

10.3390/v13091809 ◽

2021 ◽

Vol 13 (9) ◽

pp. 1809

Author(s):

Joshua J. Iszatt ◽

Alexander N. Larcombe ◽

Hak-Kim Chan ◽

Stephen M. Stick ◽

Luke W. Garratt ◽

...

Keyword(s):

Respiratory Tract Infections ◽

Phage Therapy ◽

Respiratory Infections ◽

Current Evidence ◽

Drug Resistant ◽

Data Generation ◽

Bacteriophage Therapy ◽

Efficacy Data ◽

New Antibiotics ◽

Tract Infections

The emergence of multi-drug resistant (MDR) bacteria is recognised today as one of the greatest challenges to public health. As traditional antimicrobials are becoming ineffective and research into new antibiotics is diminishing, a number of alternative treatments for MDR bacteria have been receiving greater attention. Bacteriophage therapies are being revisited and present a promising opportunity to reduce the burden of bacterial infection in this post-antibiotic era. This review focuses on the current evidence supporting bacteriophage therapy against prevalent or emerging multi-drug resistant bacterial pathogens in respiratory medicine and the challenges ahead in preclinical data generation. Starting with efforts to improve delivery of bacteriophages to the lung surface, the current developments in animal models for relevant efficacy data on respiratory infections are discussed before finishing with a summary of findings from the select human trials performed to date.

Download Full-text

Impact of SARS-CoV-2 Vaccines on Covid-19 Incidence and Mortality in the United States

10.1101/2021.11.16.21266360 ◽

2021 ◽

Author(s):

Fang Fang ◽

John David Clemens ◽

Zuo-Feng Zhang ◽

Timothy F. Brewer

Keyword(s):

Negative Binomial ◽

Herd Immunity ◽

The United States ◽

Vaccination Rate ◽

Vaccine Hesitancy ◽

Percentage Increase ◽

Protective Effects ◽

Vaccination Rates ◽

Incidence And Mortality ◽

Before And After

Background: Despite safe and effective vaccines to prevent Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2) infections and disease, a substantial minority of the US remains resistant to getting vaccinated. It is imperative to know if expanding vaccination rates could reduce community-wide Coronavirus 2019 (COVID-19) disease, not just among those vaccinated. Methods: Negative binomial models were used to estimate associations between U.S. county-level vaccination rates and county-wide COVID-19 incidence and mortality between April 23rd and September 30th, 2021. A two-week lag and a four-week lag were introduced to assess vaccination rate impact on incidence and mortality, respectively. Stratified analyses were performed for county vaccination rates >40%, and before and after Delta became the dominant variant. Findings: Among 3,070 counties, each percentage increase in population vaccination rates reduced county-wide COVID-19 incidence by 0.9% (relative risk (RR) 0.9910 (95% CI: 0.9869, 0.9952)) and mortality by 1.9% (RR 0.9807 (95% CI: 0.9745, 0.9823)). Among counties with vaccination coverage >40%, each percentage increase in vaccination rates reduced COVID-19 disease by 1.5%, RR 0.9850 (95% CI: 0.9793, 0.9952) and mortality by 2.7% (RR 0.9727 (95% CI: 0.9632, 0.9823)). These associations were not observed among counties with <40% vaccination rates. Increasing vaccination rates from 40% to 80% would have reduced COVID-19 cases by 45.4% (RR 0.5458 (95% CI: 0.4335, 0.6873)) and deaths by 67.0% (RR 0.3305 (95% CI: 0.2230, 0.4898)). An estimated 5,989,952 COVID-19 cases could have been prevented and 127,596 lives saved had US population vaccination rates increased from 40% to 80%. Interpretations: Increasing U.S. SARS-CoV-2 vaccination rates results in population-wide reductions in COVID-19 incidence and mortality. Furthermore, increasing vaccination rates above 40% has protective effects among non-vaccinated persons. Given ongoing vaccine hesitancy in the U.S., increasing vaccination rates could better protect the entire community and potentially reach herd immunity. Funding: National Cancer Institute

Download Full-text

A Prevalent Focused Human Antibody Response to the Influenza Virus Hemagglutinin Head Interface

mBio ◽

10.1128/mbio.01144-21 ◽

2021 ◽

Author(s):

Kevin R. McCarthy ◽

Jiwon Lee ◽

Akiko Watanabe ◽

Masayuki Kuraoka ◽

Lindsey R. Robinson-McCarthy ◽

...

Keyword(s):

Influenza Virus ◽

Herd Immunity ◽

Influenza Viruses ◽

Influenza Vaccines ◽

Human Antibody ◽

Human Influenza ◽

Human Antibodies ◽

Influenza Virus Hemagglutinin ◽

Selection For ◽

Rapid Appearance

The rapid appearance of mutations in circulating human influenza viruses and selection for escape from herd immunity require prediction of likely variants for an annual updating of influenza vaccines. The identification of human antibodies that recognize conserved surfaces on the influenza virus hemagglutinin (HA) has prompted efforts to design immunogens that might selectively elicit such antibodies.

Download Full-text