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1.
J R Soc Interface ; 18(175): 20200683, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33530857

RESUMO

SARS-CoV-2 is an international public health emergency; high transmissibility and morbidity and mortality can result in the virus overwhelming health systems. Combinations of social distancing, and test, trace, and isolate strategies can reduce the number of new infections per infected individual below 1, thus driving declines in case numbers, but may be both challenging and costly. These interventions must also be maintained until development and (now likely) mass deployment of a vaccine (or therapeutics), since otherwise, many susceptible individuals are still at risk of infection. We use a simple analytical model to explore how low levels of infection, combined with vaccination, determine the trajectory to community immunity. Understanding the repercussions of the biological characteristics of the viral life cycle in this scenario is of considerable importance. We provide a simple description of this process by modelling the scenario where the effective reproduction number [Formula: see text] is maintained at 1. Since the additional complexity imposed by the strength and duration of transmission-blocking immunity is not yet clear, we use our framework to probe the impact of these uncertainties. Through intuitive analytical relations, we explore how the necessary magnitude of vaccination rates and mitigation efforts depends crucially on the durations of natural and vaccinal immunity. We also show that our framework can encompass seasonality or preexisting immunity due to epidemic dynamics prior to strong mitigation measures. Taken together, our simple conceptual model illustrates the importance of individual and vaccinal immunity for community immunity, and that the quantification of individuals immunized against SARS-CoV-2 is paramount.


Assuntos
/imunologia , Imunidade Coletiva , Vacinação , Número Básico de Reprodução , Epidemias , Humanos , Sistema Imunitário , Saúde Pública , Estações do Ano
2.
J Korean Med Sci ; 36(7): e59, 2021 Feb 22.
Artigo em Inglês | MEDLINE | ID: mdl-33619920

RESUMO

The formation of herd immunity through vaccination is a key point in overcoming the coronavirus disease 2019 (COVID-19) pandemic. To acquire herd immunity, a high vaccination rate is required, which is necessary to instill confidence in the public regarding the effectiveness and safety of the vaccine. In the real-world setting, thorough preparation of components, such as priority setting, vaccine delivery, logistics, and side-effect monitoring is necessary to overcome vaccine hesitancy. Each country prioritizes vaccination since healthcare workers, nursing facility residents, and the elderly population, and similar trends are found between countries. Vaccination is performed at large centers and medical institutions operated by the country, and variations are dependent on the environment of each country. The transport of mRNA vaccines is a challenging task, and to this end, each government is striving for safe distribution. In addition, each authority operates a surveillance system to monitor the safety of vaccines, and Korea needs to produce evidence for monitoring effects and side effects with expertise. Even after the acquisition of herd immunity, COVID-19 is highly likely to remain an endemic infectious disease, and a higher immunity level may be required because of variants of the virus. If the spread of variants of concern continues, a booster vaccination may be required. Therefore, non-pharmaceutical interventions, such as social distancing, wearing a mask, and epidemiological investigation should be maintained.


Assuntos
/imunologia , /imunologia , Vacinação , Humanos , Imunidade Coletiva
4.
Clin Infect Dis ; 72(3): 515-518, 2021 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-33527122

RESUMO

While the role of children in the transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remains to be defined, children likely play an important role based on our knowledge of other respiratory viruses. Children are more likely to be asymptomatic or have milder symptoms and less likely to present for healthcare and be tested for SARS-CoV-2. Thus, our current estimates are likely under-representative of the true burden of SARS-CoV-2 in children. Given the potential direct benefit of a SARS-CoV-2 vaccine in children and the substantial indirect benefit through community protection, or "herd immunity," we argue that planning and implementation of SARS-CoV-2 vaccines should include children. Furthermore, community protection occurred after widespread implementation of prior childhood vaccines against Streptococcus pneumoniae, rubella, and rotavirus. We detail considerations for vaccine clinical trials, potential barriers to the implementation of widespread vaccination and argue why children would be an ideal target population for vaccination.


Assuntos
Vacinas Virais , Criança , Humanos , Imunidade Coletiva
5.
J Korean Med Sci ; 36(6): e54, 2021 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-33559409

RESUMO

Coronavirus disease 2019 (COVID-19), which started at the end of 2019 and has spread worldwide, has remained unabated in 2021. Since non-pharmaceutical interventions including social distancing are facing limitations in controlling COVID-19, additional absolute means to change the trend are necessary. To this end, coronavirus-specific antiviral drugs and vaccines are urgently needed, but for now, the priority is to promote herd immunity through extensive nationwide vaccination campaign. In addition to the vaccines based on the conventional technology such inactivated or killed virus or protein subunit vaccines, several vaccines on the new technological platforms, for example, nucleic acids-based vaccines delivered by viral carriers, nanoparticles, or plasmids as a medium were introduced in this pandemic. In addition to achieving sufficient herd immunity with vaccination, the development of antiviral treatments that work specifically against COVID-19 will also be necessary to terminate the epidemic completely.


Assuntos
/imunologia , /prevenção & controle , Adenoviridae/genética , /virologia , Variação Genética , Vetores Genéticos/genética , Humanos , Imunidade Coletiva , RNA Mensageiro/genética , RNA Mensageiro/imunologia , RNA Mensageiro/metabolismo , /isolamento & purificação , Glicoproteína da Espícula de Coronavírus/genética , Glicoproteína da Espícula de Coronavírus/imunologia
7.
Nat Med ; 27(2): 205-211, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33469205

RESUMO

After the recent announcement of COVID-19 vaccine efficacy in clinical trials by several manufacturers for protection against severe disease, a comprehensive post-efficacy strategy for the next steps to ensure vaccination of the global population is now required. These considerations should include how to manufacture billions of doses of high-quality vaccines, support for vaccine purchase, coordination of supply, the equitable distribution of vaccines and the logistics of global vaccine delivery, all of which are a prelude to a massive vaccination campaign targeting people of all ages. Furthermore, additional scientific questions about the vaccines remain that should be answered to improve vaccine efficacy, including questions regarding the optimization of vaccination regimens, booster doses, the correlates of protection, vaccine effectiveness, safety and enhanced surveillance. The timely and coordinated execution of these post-efficacy tasks will bring the pandemic to an effective, and efficient, close.


Assuntos
/imunologia , Ensaios Clínicos Fase III como Assunto , /fisiologia , /epidemiologia , Humanos , Imunidade Coletiva , Vacinação
9.
Vaccine ; 39(5): 780-785, 2021 01 29.
Artigo em Inglês | MEDLINE | ID: mdl-33414050

RESUMO

Although the direct health impact of Coronavirus disease (COVID-19) pandemic on child health is low, there are indirect impacts across many aspects. We compare childhood vaccine uptake in three types of healthcare facilities in Singapore - public primary care clinics, a hospital paediatric unit, and private paediatrician clinics - from January to April 2020, to baseline, and calculate the impact on herd immunity for measles. We find a 25.6% to 73.6% drop in Measles-Mumps-Rubella (MMR) uptake rates, 0.4 - 10.3% drop for Diphtheria-Tetanus-Pertussis-inactivated Polio-Haemophilus influenza (5-in-1), and 8.0-67.8% drop for Pneumococcal conjugate vaccine (PCV) across all 3 sites. Consequent herd immunity reduces to 74-84% among 12-month- to 2-year-olds, well below the 95% coverage that is protective for measles. This puts the whole community at risk for a measles epidemic. Public health efforts are urgently needed to maintain efficacious coverage for routine childhood vaccines during the COVID-19 pandemic.


Assuntos
/epidemiologia , Saúde da Criança/estatística & dados numéricos , Saúde Pública/normas , Cobertura Vacinal/estatística & dados numéricos , /prevenção & controle , Pré-Escolar , Vacina contra Difteria, Tétano e Coqueluche/administração & dosagem , Vacinas Anti-Haemophilus/administração & dosagem , Vacinas contra Hepatite B/administração & dosagem , Humanos , Imunidade Coletiva , Esquemas de Imunização , Lactente , Vacina contra Sarampo-Caxumba-Rubéola/administração & dosagem , Vacina Antipólio de Vírus Inativado/administração & dosagem , Estudos Retrospectivos , Singapura/epidemiologia
10.
JAMA Netw Open ; 4(1): e2033706, 2021 01 04.
Artigo em Inglês | MEDLINE | ID: mdl-33399860

RESUMO

Importance: Estimates of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) disease burden are needed to help guide interventions. Objective: To estimate the number of SARS-CoV-2 infections, symptomatic infections, hospitalizations, and deaths in the US as of November 15, 2020. Design, Setting, and Participants: In this cross-sectional study of respondents of all ages, data from 4 regional and 1 nationwide Centers for Disease Control and Prevention (CDC) seroprevalence surveys (April [n = 16 596], May, June, and July [n = 40 817], and August [n = 38 355]) were used to estimate infection underreporting multipliers and symptomatic underreporting multipliers. Community serosurvey data from randomly selected members of the general population were also used to validate the underreporting multipliers. Main Outcomes and Measures: SARS-CoV-2 infections, symptomatic infections, hospitalizations, and deaths. The median of underreporting multipliers derived from the 5 CDC seroprevalence surveys in the 10 states that participated in 2 or more surveys were applied to surveillance data of reported coronavirus disease 2019 (COVID-19) cases for 5 respective time periods to derive estimates of SARS-CoV-2 infections and symptomatic infections, which were summed to estimate SARS-CoV-2 infections and symptomatic infections in the US. Estimates of infections and symptomatic infections were combined with estimates of the hospitalization ratio and fatality ratio to derive estimates of SARS-CoV-2 hospitalizations and deaths. External validity of the surveys was evaluated with the April CDC survey by comparing results to 5 serosurveys (n = 22 118) that used random sampling of the general population. Internal validity of the multipliers from the 10 specific states was assessed in the August CDC survey by comparing multipliers from the 10 states to all states. A sensitivity analysis was conducted using the interquartile range of the multipliers to derive a high and low estimate of SARS-CoV-2 infections and symptomatic infections. The underreporting multipliers were then used to adjust the reported COVID-19 infections to estimate the full SARS-COV-2 disease burden. Results: Adjusting reported COVID-19 infections using underreporting multipliers derived from CDC seroprevalence studies in April (n = 16 596), May (n = 14 291), June (n = 14 159), July (n = 12 367), and August (n = 38 355), there were estimated medians of 46 910 006 (interquartile range [IQR], 38 192 705-60 814 748) SARS-CoV-2 infections, 28 122 752 (IQR, 23 014 957-36 438 592) symptomatic infections, 956 174 (IQR, 782 509-1 238 912) hospitalizations, and 304 915 (IQR, 248 253-395 296) deaths in the US through November 15, 2020. An estimated 14.3% (IQR, 11.6%-18.5%) of the US population were infected by SARS-CoV-2 as of mid-November 2020. Conclusions and Relevance: The SARS-CoV-2 disease burden may be much larger than reported COVID-19 cases owing to underreporting. Even after adjusting for underreporting, a substantial gap remains between the estimated proportion of the population infected and the proportion infected required to reach herd immunity. Additional seroprevalence surveys are needed to monitor the pandemic, including after the introduction of safe and efficacious vaccines.


Assuntos
/epidemiologia , Hospitalização/estatística & dados numéricos , Número Básico de Reprodução , /mortalidade , Estudos Transversais , Humanos , Imunidade Coletiva , Vigilância em Saúde Pública , Estudos Soroepidemiológicos , Estados Unidos/epidemiologia
11.
Science ; 371(6526): 230-231, 2021 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-33446540
12.
Artigo em Inglês | MEDLINE | ID: mdl-33431724

RESUMO

Search and find methods*) such as cluster tracing1)-6) or large-scale PCR testing**) of those who exhibit no symptoms or only mild symptoms of COVID-19 is shown by data analysis to be a powerful means to suppress the spread of COVID-19 instead of, or in addition to, lockdown of the entire population. Here we investigate this issue by analyzing the data from some cities and countries and we establish that search and find method is as powerful as lockdown of a city or a country. Moreover, in contrast to lockdown, it neither causes inconvenience to citizens nor does it disrupt the economy. Generally speaking, it is advisable that both social distancing and increased test numbers be employed to suppress spread of the virus. The product of the total test number with the rate of positive cases is the crucial index.


Assuntos
/prevenção & controle , Controle de Doenças Transmissíveis/métodos , África/epidemiologia , Infecções Assintomáticas/epidemiologia , Brasil/epidemiologia , /transmissão , China/epidemiologia , Controle de Doenças Transmissíveis/estatística & dados numéricos , Política de Saúde , Humanos , Imunidade Coletiva , Japão/epidemiologia , Los Angeles/epidemiologia , Modelos Biológicos , Modelos Estatísticos , New York/epidemiologia , Pandemias/prevenção & controle , Pandemias/estatística & dados numéricos , Quarentena , Sensibilidade e Especificidade , Suécia/epidemiologia , Tóquio/epidemiologia , Estados Unidos/epidemiologia
14.
Glob Health Res Policy ; 6(1): 3, 2021 01 29.
Artigo em Inglês | MEDLINE | ID: mdl-33509291

RESUMO

BACKGROUND: Epidemiological data indicate that a large part of population needs to be vaccinated to achieve herd immunity. Hence, it is of high importance for public health officials to know whether people are going to get vaccinated for COVID-19. The objective of the present study was to examine the willingness of adult residents in Greece to receive a COVID-19 vaccine. METHODS: A cross-sectional was survey conducted among the adult general population of Greece between April 28, 2020 to May 03, 2020 (last week of lockdown), using a mixed methodology for data collection: Computer Assisted Telephone Interviewing (CATI) and Computer Assisted web Interviewing (CAWI). Using a sample size calculator, the target sample size was found to be around 1000 respondents. To ensure a nationally representative sample of the urban/rural population according to the Greek census 2011, a proportionate stratified by region systematic sampling procedure was used to recruit particpants. Data collection was guided through a structured questionnaire. Regarding willingness to COVID-19 vaccination, participants were asked to answer the following question: "If there was a vaccine available for the novel coronavirus, would you do it?" RESULTS: Of 1004 respondents only 57.7% stated that they are going to get vaccinated for COVID-19. Respondents aged > 65 years old, those who either themselves or a member of their household belonged to a vulnerable group, those believing that the COVID-19 virus was not developed in laboratories by humans, those believing that coronavirus is far more contagious and lethal compared to the H1N1 virus, and those believing that next waves are coming were statistically significantly more likely to be willing to get a COVID-19 vaccine. Higher knowledge score regarding symptoms, transmission routes and prevention and control measures against COVID-19 was significantly associated with higher willingness of respondents to get vaccinated. CONCLUSION: A significant proportion of individuals in the general population are unwilling to receive a COVID-19 vaccine, stressing the need for public health officials to take immediate awareness-raising measures.


Assuntos
/administração & dosagem , Conhecimentos, Atitudes e Prática em Saúde , Aceitação pelo Paciente de Cuidados de Saúde/estatística & dados numéricos , Adulto , Idoso , Estudos Transversais , Feminino , Grécia , Humanos , Imunidade Coletiva , Entrevistas como Assunto , Masculino , Pessoa de Meia-Idade , Saúde Pública
15.
Sci Rep ; 11(1): 2003, 2021 01 21.
Artigo em Inglês | MEDLINE | ID: mdl-33479450

RESUMO

This paper studies the social acceptability and feasibility of a focused protection strategy against coronavirus disease 2019 (COVID-19). We propose a control scheme to develop herd immunity while satisfying the following two basic requirements for a viable policy option. The first requirement is social acceptability: the overall deaths should be minimized for social acceptance. The second is feasibility: the healthcare system should not be overwhelmed to avoid various adverse effects. To exploit the fact that the disease severity increases considerably with age and comorbidities, we assume that some focused protection measures for those high-risk individuals are implemented and the disease does not spread within the high-risk population. Because the protected population has higher severity ratios than the unprotected population by definition, the protective measure can substantially reduce mortality in the whole population and also avoid the collapse of the healthcare system. Based on a simple susceptible-infected-recovered model, social acceptability and feasibility of the proposed strategy are summarized into two easily computable conditions. The proposed framework can be applied to various populations for studying the viability of herd immunity strategies against COVID-19. For Japan, herd immunity may be developed by the proposed scheme if [Formula: see text] and the severity rates of the disease are 1/10 times smaller than the previously reported value, although as high mortality as seasonal influenza is expected.


Assuntos
/prevenção & controle , Controle de Doenças Transmissíveis/métodos , /metabolismo , Transmissão de Doença Infecciosa/prevenção & controle , Estudos de Viabilidade , Humanos , Imunidade Coletiva/imunologia , Imunidade Coletiva/fisiologia , Japão/epidemiologia , Modelos Estatísticos , Pandemias
17.
Rev. esp. quimioter ; 33(6): 392-398, dic. 2020. tab
Artigo em Espanhol | IBECS | ID: ibc-195990

RESUMO

Los coronavirus (CoVs) son un amplio grupo de virus en el que se encuentra el SARS-CoV-2 (familia Coronaviridae, subfamilia Coronavirinae, género Betacoronavirus y subgénero Sarbecovirus). Sus principales proteínas estructurales son la de membrana (M), la de envoltura (E), la nucleocápside (N) y la espicular (S). La respuesta inmune frente a SARS-CoV-2 implica la vertiente celular y humoral, con anticuerpos neutralizantes potencialmente defensivos fundamentalmente dirigidos frente al antígeno S. Aunque los datos de seroprevalencia se asumen muy frecuentemente como marcadores de protección, no necesariamentelo son. En España se estima que al menos cuatro quintas partes de la población deberían estar inmuno-protegidas para asegurar la inmunidad de grupo. Dada la alta tasa de letalidad por COVID-19, la adquisición de esta protección únicamente mediante el contagio natural no es asumible y se debe abogar por otras medidas como puede ser la inmunización masiva. En la actualidad existen varios prototipos de vacunas (que incluyen virus vivos, vectores virológicos, péptidos y proteínas y ácidos nucleicos) en diversas etapas de evaluación clínica. Se prevé que en breve alguna de estas nuevas vacunas se encuentre ya disponible en el mercado. En este texto se revisan aspectos relacionados con estos asuntos


The coronavirus are a wide group of viruses among that the SARS-CoV-2 is included (family Coronaviridae, subfamily Coronavirinae, genus Betacoronavirus and subgenus Sarbecovirus). Its main structural proteins are the membrane (M), the envelope (E), the nucleocapsid (N) and spike (S). The immune response to SARS-CoV-2 involves the cellular and the humoral sides, with neutralizing antibodies fundamentally directed against the S antigen. Although the seroprevalence data are frequently assumed as protection markers, no necessarily they are. In Spain, it is estimated that, to assure the herd immunity, at least four-fifths of the population should be immunoprotected. Due the high fatality rate of COVID-19, the acquisition of the protection only by the natural infection it not assumable and other measures as the mass immunization are required. Currently, there are several vaccine prototypes (including life virus, viral vectors, peptides and proteins and nucleic acid) in different phase of clinical evaluation. Foreseeably, some of these news vaccines would be soon commercially available. In this text, aspects related to these issues are reviewed


Assuntos
Humanos , Infecções por Coronavirus/prevenção & controle , Pneumonia Viral/prevenção & controle , Betacoronavirus/imunologia , Vacinação , Vacinas Virais/imunologia , Pandemias , Anticorpos Antivirais/imunologia , Infecções por Coronavirus/epidemiologia , Infecções por Coronavirus/imunologia , Ensaios Clínicos como Assunto/classificação , Reações Cruzadas/imunologia , Imunidade Coletiva/imunologia , Imunização , Testes de Neutralização/métodos , Proteínas Estruturais Virais
20.
PLoS One ; 15(12): e0242132, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33326421

RESUMO

A quantitative COVID-19 model that incorporates hidden asymptomatic patients is developed, and an analytic solution in parametric form is given. The model incorporates the impact of lock-down and resulting spatial migration of population due to announcement of lock-down. A method is presented for estimating the model parameters from real-world data, and it is shown that the various phases in the observed epidemiological data are captured well. It is shown that increase of infections slows down and herd immunity is achieved when active symptomatic patients are 10-25% of the population for the four countries we studied. Finally, a method for estimating the number of asymptomatic patients, who have been the key hidden link in the spread of the infections, is presented.


Assuntos
/patologia , Imunidade Coletiva , Modelos Teóricos , Infecções Assintomáticas/epidemiologia , /imunologia , França/epidemiologia , Humanos , Itália/epidemiologia , Japão/epidemiologia , Quarentena , Suíça/epidemiologia
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