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1.
Med Microbiol Immunol ; 211(4): 195-210, 2022 Aug.
Article in English | MEDLINE | ID: mdl-35780233

ABSTRACT

In the fight against coronavirus infection, control of the immune response is of decisive importance, an important component of which is the seroprevalence of antibodies to SARS-CoV-2. Immunity to SARS-CoV-2 is formed either naturally or artificially through vaccination. The purpose of this study was to assess the seroprevalence of antibodies to SARS-CoV-2 in the population of Kyrgyzstan. A cross-sectional randomized study of seroprevalence was carried out according to a program developed by Rospotrebnadzor and the St. Petersburg Pasteur Institute, taking into account WHO recommendations. The ethics committees of the Association of Preventive Medicine (Kyrgyzstan) and the St. Petersburg Pasteur Institute (Russia) approved the study. Volunteers (9471) were recruited, representing 0.15% (95% CI 0.14-0.15) of the total population, randomized by age and region. Plasma antibodies (Abs) to the nucleocapsid antigen (Nag) were determined. In vaccinated individuals, Abs to the SARS-CoV-2 receptor-binding domain antigen (RBDag) were determined. Differences were considered statistically significant at p < 0.05. The SARS-CoV-2 Nag Ab seroprevalence was 48.7% (95% CI 47.7-49.7), with a maximum in the 60-69 age group [59.2% (95% CI 56.6-61.7)] and a minimum in group 1-17 years old [32.7% (95 CI: 29.4-36.1)]. The highest proportion of seropositive individuals was in the Naryn region [53.3% (95% CI 49.8-56.8)]. The lowest share was in Osh City [38.1% (95% CI 32.6-43.9)]. The maximum SARS-CoV-2 Nag seropositivity was found in the health-care sector [57.1% (95% CI 55.4-58.8)]; the minimum was seen among artists [38.6% (95% CI 26.0-52.4)]. Asymptomatic SARS-CoV-2 Nag seropositivity was 77.1% (95% CI 75.6-78.5). Vaccination with Sputnik V or Sinopharm produced comparable Ab seroprevalence. SARS-CoV-2 Nag seropositivity in the Kyrgyz population was 48.75% (95% CI 47.7-49.7), with the mass vaccination campaign undoubtedly benefitting the overall situation.


Subject(s)
COVID-19 , Immunity, Herd , SARS-CoV-2 , Adolescent , Antibodies, Viral , COVID-19/epidemiology , Child , Child, Preschool , Cross-Sectional Studies , Humans , Infant , Kyrgyzstan/epidemiology , Seroepidemiologic Studies
2.
Multimedia | Multimedia Resources | ID: multimedia-9732

ABSTRACT

Também chamada de "imunidade de grupo". O vídeo apresenta conceitos sobre imunidade coletiva ou de rebanho, quando parte da população desenvolve anticorpos contra determinado agente patológico. No caso do novo coronavírus, a imunidade coletiva só será possível se uma grande parcela da população estiver vacinada contra a doença. O aplicativo FioLibras é um projeto do Instituto de Comunicação e Informação Científica e Tecnológica em Saúde da Fundação Oswaldo Cruz (Icict/Fiocruz), em parceria com o Núcleo de Estudos em Diversidade e Inclusão de Surdos da Universidade Federal Fluminense (Nuedis/UFF), e conta com financiamento do Fundo de Inovação da Fiocruz e do Ministério da Saúde, por meio do Programa Fiocruz de Fomento à Inovação (Inova Fiocruz).


Subject(s)
Immunity, Herd , Coronavirus Infections , Information Dissemination , Sign Language , e-Accessibility
3.
Phys Rev E ; 105(5): L052301, 2022 May.
Article in English | MEDLINE | ID: mdl-35706197

ABSTRACT

We study how the herd immunity threshold and the expected epidemic size depend on homophily with respect to vaccine adoption. We find that the presence of homophily considerably increases the critical vaccine coverage needed for herd immunity and that strong homophily can push the threshold entirely out of reach. The epidemic size monotonically increases as a function of homophily strength for a perfect vaccine, while it is maximized at a nontrivial level of homophily when the vaccine efficacy is limited. Our results highlight the importance of vaccination homophily in epidemic modeling.


Subject(s)
Epidemics , Immunity, Herd , Epidemics/prevention & control , Vaccination
5.
J Math Biol ; 85(1): 2, 2022 Jun 30.
Article in English | MEDLINE | ID: mdl-35773525

ABSTRACT

We study a susceptible-exposed-infected-recovered (SEIR) model considered by Aguas et al. (In: Herd immunity thresholds for SARS-CoV-2 estimated from unfolding epidemics, 2021), Gomes et al. (In: J Theor Biol. 540:111063, 2022) where individuals are assumed to differ in their susceptibility or exposure to infection. Under this heterogeneity assumption, epidemic growth is effectively suppressed when the percentage of the population having acquired immunity surpasses a critical level - the herd immunity threshold - that is lower than in homogeneous populations. We derive explicit formulas to calculate herd immunity thresholds and stable configurations, especially when susceptibility or exposure are gamma distributed, and explore extensions of the model.


Subject(s)
COVID-19 , Epidemics , COVID-19/epidemiology , Humans , Immunity, Herd , Reinfection/epidemiology , SARS-CoV-2
6.
PLoS One ; 17(5): e0267840, 2022.
Article in English | MEDLINE | ID: mdl-35552553

ABSTRACT

We introduce a novel compartmental model accounting for the effects of vaccine efficacy, deployment rates and timing of initiation of deployment. We simulate different scenarios and initial conditions, and we find that higher abundancy and rate of deployment of low efficacy vaccines lowers the cumulative number of deaths in comparison to slower deployment of high efficacy vaccines. We also forecast that, at the same daily deployment rate, the earlier introduction of vaccination schemes with lower efficacy would also lower the number of deaths with respect to a delayed introduction of high efficacy vaccines, which can however, still achieve lower numbers of infections and better herd immunity.


Subject(s)
Vaccination , Vaccines , Immunity, Herd
7.
Cien Saude Colet ; 27(5): 1843-1848, 2022 May.
Article in Spanish, English | MEDLINE | ID: mdl-35544813

ABSTRACT

Although communicable diseases affect our bodies, they occur in a society that interprets and gives them meaning. Herd immunity provides the body protection; however, long-term protection requires shifts in the way people interpret and respond to disease, cultural transformation that enables the development of the knowledge, habits and skills that make herd immunity feasible and sustainable. Herd culture allows individuals to protect themselves and restrict their liberty in order to protect others; it is a form of exercising positive liberty and a necessary complement to herd immunity in a democratic society.


Aunque las enfermedades transmisibles afectan nuestros cuerpos, ocurren en una sociedad que las interpreta y dota de significado, y cuyos individuos causan o evitan. La inmunidad de rebaño permite lograr una protección del cuerpo, sin embargo, para su sustentabilidad, se requiere de cambios en la manera cómo las personas interpretan y responden a la enfermedad, de transformaciones culturales que permitan desarrollar conocimientos, hábitos y destrezas que hagan factible y sostenible la inmunidad de rebaño. La cultura de rebaño permite a los individuos protegerse y restringir su libertad para proteger a los demás, es una forma de ejercicio de la libertad positiva y el complemento necesario de la inmunidad del rebaño en la sociedad democrática.


Subject(s)
Communicable Diseases , Immunity, Herd , Exercise , Humans , Records , Vaccination
8.
Epidemics ; 39: 100581, 2022 06.
Article in English | MEDLINE | ID: mdl-35636311

ABSTRACT

We present a country specific method to calculate the COVID-19 vaccination coverage needed for herd immunity by considering age structure, age group-specific contact patterns, relative infectivity and susceptibility of children to adults, vaccination effectiveness and seroprevalence prior to vaccination. We find that across all six countries, vaccination of adults age 60 and above has little impact on Reff and this is could be due to the smaller number of contacts between this age group and the rest of the population according to the contact matrices used. If R0 is above 6, herd immunity by vaccine alone is unattainable for most countries either if vaccination is only available for adults or that vaccine effectiveness is lower at 65% against symptomatic infections. In this situation, additional control measures, booster shots, if they improve protection against infection, or the extension of vaccination to children, are required. For a highly transmissible variant with R0 up to 8, herd immunity is possible for all countries and for all four scenarios of varying relative infectivity and susceptibility of children compared to adults, if vaccine effectiveness is very high at 95% against symptomatic infections and that high vaccination coverage is achieved for both adults and children. In addition, we show that the effective reproduction number will vary between countries even if the same proportion of the population is vaccinated, depending on the demographics, the contact rates and the previous pre-vaccination seroprevalence in the country. This therefore means that care must be taken in extrapolating population level impacts of certain vaccine coverages from one country to another.


Subject(s)
COVID-19 , Immunity, Herd , Adult , COVID-19/epidemiology , COVID-19/prevention & control , COVID-19 Vaccines , Child , Humans , Middle Aged , Seroepidemiologic Studies , Vaccination/methods , Vaccination Coverage
9.
J R Soc Med ; 115(6): 239-240, 2022 06.
Article in English | MEDLINE | ID: mdl-35616315
10.
Viruses ; 14(4)2022 04 16.
Article in English | MEDLINE | ID: mdl-35458560

ABSTRACT

Human rabies can be prevented through mass dog vaccination campaigns; however, in rabies endemic countries, pulsed central point campaigns do not always achieve the recommended coverage of 70%. This study describes the development of a novel approach to sustain high coverage based on decentralized and continuous vaccination delivery. A rabies vaccination campaign was conducted across 12 wards in the Mara region, Tanzania to test this approach. Household surveys were used to obtain data on vaccination coverage as well as factors influencing dog vaccination. A total 17,571 dogs were vaccinated, 2654 using routine central point delivery and 14,917 dogs using one of three strategies of decentralized continuous vaccination. One month after the first vaccination campaign, coverage in areas receiving decentralized vaccinations was higher (64.1, 95% Confidence Intervals (CIs) 62.1-66%) than in areas receiving pulsed vaccinations (35.9%, 95% CIs 32.6-39.5%). Follow-up surveys 10 months later showed that vaccination coverage in areas receiving decentralized vaccinations remained on average over 60% (60.7%, 95% CIs 58.5-62.8%) and much higher than in villages receiving pulsed vaccinations where coverage was on average 32.1% (95% CIs 28.8-35.6%). We conclude that decentralized continuous dog vaccination strategies have the potential to improve vaccination coverage and maintain herd immunity against rabies.


Subject(s)
Dog Diseases , Rabies Vaccines , Rabies , Animals , Dog Diseases/prevention & control , Dogs , Immunity, Herd , Rabies/epidemiology , Rabies/prevention & control , Rabies/veterinary , Vaccination/veterinary , Vaccination Coverage
11.
Internist (Berl) ; 63(5): 476-483, 2022 May.
Article in German | MEDLINE | ID: mdl-35376975

ABSTRACT

Due to the effectiveness of vaccines some particularly threatening infectious diseases have become rare; however, vaccines are meanwhile the victims of their own success. Due to insufficient compliance and inadequate vaccination rates, there is a danger that the effectiveness of vaccination as a preventive measure will continuously disappear. In 2019 the World Health Organization classified doubts on the effectiveness of vaccines as 1 of the 10 greatest dangers to health worldwide. This article discusses important questions on vaccinations and vaccines as well as their effects in the interplay with the immune system. The following topics are covered: comparison of naturally acquired immunity and that acquired by vaccination, factors that necessitate a refresher vaccination, the role of herd immunity, prerequisites for successful eradication of a disease, influence of various T cells on the effect of vaccination, the role of immunologic memory, factors that influence protection by vaccination, vaccinations in cases of immunodeficiency, the potential and areas of implementation of passive immunization. In view of the corona pandemic and the running vaccination campaign, it must be hoped that this triggers a general renaissance of vaccinations against infectious diseases.


Subject(s)
Immunologic Memory , Vaccines , Humans , Immunity, Herd , Immunization Programs , Vaccination
12.
Nat Rev Immunol ; 22(6): 333-334, 2022 06.
Article in English | MEDLINE | ID: mdl-35440758
13.
Washington, D.C.; OPAS; 2022-04-28.
in Portuguese | PAHO-IRIS | ID: phr-55946

ABSTRACT

Um dos componentes essenciais de um sistema de vacinação seguro é a vigilância de eventos supostamente atribuíveis à vacinação ou imunização (ESAVI). Por meio dessa vigilância, busca-se detectar precocemente qualquer evento adverso que ocorra após a vacinação, a fim de controlar e classificar os riscos relacionados à vacina ou aos processos de fabricação, transporte, armazenamento e aplicação, bem como a qualquer situação inerente à pessoa vacinada ou para afastar a relação de tais eventos com a vacina. Este manual foi adaptado para a Região das Américas a partir do Manual Global para Vigilância de Eventos Adversos Pós-Vacinação, publicado pela Organização Mundial da Saúde em 2014. Ele fornece uma revisão técnica abrangente de todos os processos e procedimentos para implementar e operar sistemas de alta qualidade para a vigilância de ESAVI. Reúne a experiência de vários especialistas em segurança de vacinas da Região e do mundo, especialistas de programas nacionais de imunização, autoridades reguladoras nacionais e outras instituições que desenvolveram conhecimento relevante para a vigilância desses eventos. Espera-se que este documento sirva de guia para que os responsáveis pelos programas nacionais de imunização, os diretores de farmacovigilância das autoridades reguladoras nacionais e as demais instituições responsáveis pelo monitoramento da segurança das vacinas tenham ferramentas que facilitem sua tarefa e permitam a aplicação de normas internacionais em temas como detecção e investigação de ESAVI, análise de causalidade, gerenciamento de dados e comunicação de risco, entre outros.


Subject(s)
Immunization , Immunization Programs , Immunity, Herd , Mass Vaccination , Immunization, Passive , Vaccines , Vaccines, Attenuated , Adjuvants, Immunologic , Anti-Bacterial Agents
14.
Washington, D.C.; PAHO; 2022-04-28.
in English | PAHO-IRIS | ID: phr-55945

ABSTRACT

One of the essential components of the safe vaccination system is the surveillance of events supposedly attributable to vaccination or immunization (ESAVI). This surveillance is aimed at early detection of any adverse events that may occur following immunization, in order to monitor and classify risks related to a vaccine, the manufacturing process, transportation, storage, administration, and any preexisting condition in the vaccinated person, and to rule out an association between the event and the vaccine. This manual has been adapted for the Region of the Americas from the Global Manual on Surveillance of Adverse Events Following Immunization, published by the World Health Organization in 2014. It provides a comprehensive technical review of all processes and procedures for applying and implementing high-quality ESAVI surveillance systems. It brings together the expertise of vaccine safety specialists from the Region and from around the world, experts from national immunization programs, national regulatory bodies, and other institutions that have developed relevant knowledge on surveillance of these events. It is hoped that this document will serve as a guide to provide national immunization program managers, pharmacovigilance officers of national regulatory authorities, and other institutions responsible for monitoring vaccine safety with tools to facilitate their task, enabling them to apply international standards to issues such as event detection, event investigation, causality assessment, management of ESAVI data, and risk communication.


Subject(s)
Immunization , Immunization Programs , Immunity, Herd , Mass Vaccination , Immunization, Passive , Vaccines , Vaccines, Attenuated , Adjuvants, Immunologic , Anti-Bacterial Agents
15.
Epidemics ; 38: 100544, 2022 03.
Article in English | MEDLINE | ID: mdl-35240545

ABSTRACT

To contain the propagation of emerging diseases that are transmissible from human to human, non-pharmaceutical interventions (NPIs) aimed at reducing the interactions between humans are usually implemented. One example of the latter kind of measures is social distancing, which can be either policy-driven or can arise endogenously in the population as a consequence of the fear of infection. However, if NPIs are lifted before the population reaches herd immunity, further re-introductions of the pathogen would lead to secondary infections. Here we study the effects of different social distancing schemes on the large scale spreading of diseases. Specifically, we generalize metapopulation models to include social distancing mechanisms at the subpopulation level and model short- and long-term strategies that are fed with local or global information about the epidemics. We show that different model ingredients might lead to very diverse outcomes in different subpopulations. Our results suggest that there is not a unique answer to the question of whether contention measures are more efficient if implemented and managed locally or globally and that model outcomes depends on how the full complexity of human interactions is taken into account.


Subject(s)
COVID-19 , Epidemics , COVID-19/epidemiology , Humans , Immunity, Herd , Physical Distancing
16.
Science ; 375(6585): 1088-1089, 2022 03 11.
Article in English | MEDLINE | ID: mdl-35271331

ABSTRACT

How much do COVID-19 vaccines reduce transmission? The answer is a moving target.


Subject(s)
COVID-19 , Immunity, Herd , COVID-19/prevention & control , COVID-19 Vaccines , Humans , Immunity, Herd/immunology , SARS-CoV-2 , Vaccination/veterinary
17.
Soc Sci Med ; 298: 114800, 2022 04.
Article in English | MEDLINE | ID: mdl-35287066

ABSTRACT

Despite unprecedented progress in developing COVID-19 vaccines, global vaccination levels needed to reach herd immunity remain a distant target, while new variants keep emerging. Obtaining near universal vaccine uptake relies on understanding and addressing vaccine resistance. Simple questions about vaccine acceptance however ignore that the vaccines being offered vary across countries and even population subgroups, and differ in terms of efficacy and side effects. By using advanced discrete choice models estimated on stated choice data collected in 18 countries/territories across six continents, we show a substantial influence of vaccine characteristics. Uptake increases if more efficacious vaccines (95% vs 60%) are offered (mean across study areas = 3.9%, range of 0.6%-8.1%) or if vaccines offer at least 12 months of protection (mean across study areas = 2.4%, range of 0.2%-5.8%), while an increase in severe side effects (from 0.001% to 0.01%) leads to reduced uptake (mean = -1.3%, range of -0.2% to -3.9%). Additionally, a large share of individuals (mean = 55.2%, range of 28%-75.8%) would delay vaccination by 3 months to obtain a more efficacious (95% vs 60%) vaccine, where this increases further if the low efficacy vaccine has a higher risk (0.01% instead of 0.001%) of severe side effects (mean = 65.9%, range of 41.4%-86.5%). Our work highlights that careful consideration of which vaccines to offer can be beneficial. In support of this, we provide an interactive tool to predict uptake in a country as a function of the vaccines being deployed, and also depending on the levels of infectiousness and severity of circulating variants of COVID-19.


Subject(s)
COVID-19 , Vaccines , COVID-19/prevention & control , COVID-19 Vaccines/therapeutic use , Humans , Immunity, Herd , Vaccination
18.
Article in Spanish | PAHO-IRIS | ID: phr-55850

ABSTRACT

[RESUMEN]. Ante la pandemia de la enfermedad por el coronavirus 2019 (COVID-19, por su sigla en inglés), la preocupación de toda la humanidad es alcanzar la anhelada inmunidad colectiva que permita superar esta crisis sanitaria en la que se vive. Estimar la eficacia que se podría alcanzar en una población al combinar vacunas de distintas marcas o tecnologías sería un elemento valioso para los tomadores de decisiones en el ámbito de la salud pública en la presente pandemia y en futuros escenarios similares. El presente artículo busca brindar una fórmula matemática que permita estimar la probable eficacia contra la COVID-19 al administrar dos vacunas en una población específica. Estas vacunas, aplicadas en serie, podrían ser de tecnologías y marcas distintas.


[ABSTRACT]. In the face of the coronavirus disease 2019 (COVID-19) pandemic, the entire world is concerned with achieving desired herd immunity to overcome the current health crisis. Estimating the efficacy that could be attained in a population by combining vaccines of different brands or technologies would be a valuable asset for public health decision-makers in the present pandemic and in similar future scenarios. This article provides a mathematical formula to estimate probable efficacy against COVID-19 when administering two vaccines in a specific population. These vaccines, given in a series, could be of different technologies and brands.


[RESUMO]. A pandemia da doença causada pelo coronavírus 2019 (COVID-19) criou a preocupação em toda a humanidade em alcançar a tão desejada imunidade coletiva para superar esta crise sanitária que o mundo está vivendo. Estimar a possível eficácia a ser obtida em uma população ao combinar vacinas de diferentes marcas ou tecnologias seria um recurso inestimável às autoridades de saúde pública na pandemia atual e em situações semelhantes futuras. O presente artigo apresenta uma fórmula matemática para estimar a provável eficácia contra a COVID-19 da vacinação em série com duas vacinas de diferentes marcas e tecnologias em uma determinada população.


Subject(s)
COVID-19 Vaccines , Efficacy , Immunity, Herd , COVID-19 Vaccines , Efficacy , Immunity, Herd , COVID-19 Vaccines , Efficacy , Immunity, Herd
19.
J R Soc Interface ; 19(188): 20210896, 2022 03.
Article in English | MEDLINE | ID: mdl-35259954

ABSTRACT

An age-structured SEIR model simulates the propagation of COVID-19 in the population of Northern Ireland. It is used to identify optimal timings of short-term lockdowns that enable long-term pandemic exit strategies by clearing the threshold for herd immunity or achieving time for vaccine development with minimal excess deaths.


Subject(s)
COVID-19 , COVID-19/epidemiology , COVID-19/prevention & control , Communicable Disease Control , Humans , Immunity, Herd , Northern Ireland/epidemiology , SARS-CoV-2
20.
J Correct Health Care ; 28(2): 71-74, 2022 04.
Article in English | MEDLINE | ID: mdl-35143356

ABSTRACT

Controlling the transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been challenging in the community and prison systems. Where herd immunity lies for this virus is unknown, although estimates have ranged from 60% to 80%. Since the start of the pandemic, there have been multiple SARS-CoV-2 outbreaks within U.S. prison systems, which may provide more insight on where true herd immunity lies. We reviewed data from the California Department of Corrections and Rehabilitation to investigate the cumulative incidence of infection and found levels in 14 (40%) of 35 prisons were >60%. These data and existing literature suggest that in prison environments, prevalence of immunity often needs to reach >70% before transmission slows. Similar levels may be needed in the general population before transmission is suppressed.


Subject(s)
COVID-19 , Prisoners , COVID-19/epidemiology , Humans , Immunity, Herd , Incidence , SARS-CoV-2
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