scholarly journals Dynamic Change of COVID-19 Seroprevalence among Asymptomatic Population in Tokyo during the Second Wave

2020 ◽  
Author(s):  
Sawako Hibino ◽  
Kazutaka Hayashida ◽  
Andrew C Ahn ◽  
Yasutaka Hayashida
Keyword(s):  
Healthy Volunteers ◽  
Dynamic Change ◽  
Herd Immunity ◽  
Temporal Correlation ◽  
Population Level ◽  
Serological Response ◽  
Japanese Company ◽  
Serological Tests ◽  
Test Kit ◽  
Second Wave

Importance: Fatality rates related to COVID-19 in Japan have been low compared to Western Countries and have decreased despite the absence of lockdown. Serological tests monitored across the course of the second wave can provide insights into the population-level prevalence and dynamic patterns of COVID-19 infection. Objective: To assess changes in COVID-19 seroprevalence among asymptomatic employees working in Tokyo during the second wave. Design: We conducted an observational cohort study. Healthy volunteers working for a Japanese company in Tokyo were enrolled from disparate locations to determine seropositivity against COVID19 from May 26 to August 25, 2020. COVID-19 IgM and IgG antibodies were determined by a rapid COVID19 IgM/IgG test kit using fingertip blood. Across the company, tests were performed and acquired weekly. For each participant, serology tests were offered twice, separated by approximately a month, to provide self-reference of test results and to assess for seroconversion and seroreversion. Setting: Workplace setting within a large company. Participants: Healthy volunteers from 1877 employees of a large Japanese company were recruited to the study from 11 disparate locations across Tokyo. Participants having fever, cough, or shortness of breath at the time of testing were excluded. Main Outcome(s) and Measure(s): Seropositivity rate (SPR) was calculated by pooled data from each two-weeks window across the cohort. Either IgM or IgG positivity was defined as seropositive. Changes in immunological status against SARS-CoV-2 were determined by comparing results between two tests obtained from the same individual. Results: Six hundred fifteen healthy volunteers (mean + SD 40.8 + 10.0; range 19-69; 45.7 % female) received at least one test. Seroprevalence increased from 5.8 % to 46.8 % over the course of the summer. The most dramatic increase in SPR occurred in late June and early July, paralleling the rise in daily confirmed cases within Tokyo, which peaked on August 4. Out of the 350 individuals (mean + SD 42.5 + 10.0; range 19-69; 46.0 % female) who completed both offered tests, 21.4 % of those individuals who tested seronegative became seropositive and seroreversion was found in 12.2 % of initially seropositive participants. 81.1% of IgM positive cases at first testing became IgM negative in approximately one month. Conclusions and Relevance: COVID-19 infection may have spread widely across the general population of Tokyo despite the very low fatality rate. Given the temporal correlation between the rise in seropositivity and the decrease in reported COVID-19 cases that occurred without a shut-down, herd immunity may be implicated. Sequential testing for serological response against COVID-19 is useful for understanding the dynamics of COVID-19 infection at the population-level.

scholarly journals Dynamic change of COVID-19 seroprevalence among asymptomatic office workers in Tokyo from May through Dec 2020 during the second waves of COVID-19.

2021 ◽  
Author(s):  
Sawako Hibino ◽  
Kazutaka Hayashida ◽  
Andrew C Ahn ◽  
Yasutaka Hayashida
Keyword(s):  
Dynamic Change ◽  
Herd Immunity ◽  
Temporal Correlation ◽  
Population Level ◽  
Office Workers ◽  
Severe Illness ◽  
Serological Response ◽  
Test Kit ◽  
Asymptomatic Individuals

Abstract Background COVID-19 deaths per capita in Japan have been low compared to Western Countries despite the absence of the lockdown. It is still unclear either the less spreading of the virus or, the less progression to the severe illness. Therefore, it is crucial to determine the seropositivity rates (SPR) in the general population. We determined SPR in healthy office workers in Tokyo with validation of results by comparing two test results from the same individual a month apart.Method Healthy office workers for a Japanese company in Tokyo were determined seropositivity against COVID19 weekly from May 26 to August 25, 2020, by a rapid COVID19 IgM/IgG test kit using fingertip blood. SPR was calculated by pooled data from each two-week window. For each participant, tests were offered twice, separated by a month, to provide self-reference to validate the results. The seropositive individuals were offered a follow-up test on Dec 8th or 15th, 2020, when the third wave loomed in Tokyo, to determine the persistence of the seropositivity.Results 615 volunteers (mean + SD 40.8 + 10.0; 45.7 % female) from 11 discrete locations received at least one test. 350 individuals completed two tests a month apart. The comparison showed that 93.2 % showed reasonable status changes and no instances with physiologically unexpected changes (e.g., IgG (+) turns IgM(+) in a month). Seroprevalence increased from 5.8 % to 46.8 %, paralleling the rise of the cases in Tokyo. Among 152 seropositive participants, 74 participants underwent the follow-up test in Dec 2020. 40.5 % turned seronegative in four months (mean ± S.D. 120 ± 17 days).Conclusion COVID-19 infection may have spread widely in Tokyo despite the low fatality. Given the temporal correlation between the rise in seropositivity and the peak out of COVID-19 cases without a lockdown, temporary herd immunity might be achieved. However, the relatively short-lived antibodies among the asymptomatic individuals may explain why the herd immunity strategy has not succeeded, and COVID-19 resurgence happens every several months. Moreover, sequential testing for serological response against COVID-19 is useful for understanding the dynamics of COVID-19 infection at the population level.

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 Evaluation of Vaccination Strategy Against Rabies in Hong Kong Macaques

2021 ◽  
Author(s):  
Omid Nekouei ◽  
Paolo Martelli ◽  
Sophie St-Hilaire ◽  
Hui Suk Wai ◽  
Karthiyani Krishnasamy ◽  
...  
Keyword(s):  
Hong Kong ◽  
Vaccination Strategy ◽  
Elisa Test ◽  
Enzyme Linked Immunosorbent Assay ◽  
Serological Response ◽  
Test Kit ◽  
In The Wild ◽  
The Government ◽  
Specific Association ◽  
Antibody Levels

Rabies is a fatal zoonotic disease that can affect all mammals. Following the directives of the rabies ordinance of the Government of Hong Kong, all wild macaques captured under an ongoing sterilization program (since 2000) were vaccinated against rabies. The main objective of this study was to assess the serological response to rabies vaccination in the population of Hong Kong macaques. An inactivated rabies vaccine was subcutaneously administered to captured macaques under anesthesia. In a 2015 field survey, blood samples from the animals were collected and stored in -80℃ freezer. In July 2021, all frozen sera from vaccinated animals were prepared and tested for antibodies against rabies virus using a commercial enzyme-linked immunosorbent assay (ELISA) test. The test results were dichotomized at the recommended cut-off point of the test kit. Sixty-five samples from the vaccinated macaques were available for this study. All of these animals had received at least one dose of vaccine (1 vaccination) between 2008 and 2015. The interval between the 1 vaccination and blood sampling dates ranged from 21 to 2,779 days. Only five of the 65 macaques had a second vaccination record at the time of sampling; all five had high antibody levels. Among the remaining macaques, 77% (46/60) were positive for rabies antibodies. No specific association was observed between the post-vaccination period and the antibody titer of these macaques and no adverse reactions to vaccination were reported. The current vaccination strategy in Hong Kong macaques appears to effectively elicit rabies antibodies in a high proportion of macaque populations in the wild (78-87%). However, reaching the precise level of protection against a potential challenge with the virus should further be investigated.

scholarly journals Impact of COVID-19 Variants on the Second Wave in India and Subsequent Discretion of Possibilities of the Third Wave

2021 ◽  
pp. 115-126
Author(s):  
Sudarshan Ramaswamy ◽  
Meera Dhuria ◽  
Sumedha M. Joshi ◽  
Deepa H Velankar
Keyword(s):  
Herd Immunity ◽  
Sir Model ◽  
The Other ◽  
Third Wave ◽  
Focal Points ◽  
Current Analysis ◽  
The Third ◽  
The Impact ◽  
Second Wave ◽  
Insight Into

Introduction: Epidemiological comprehension of the COVID-19 situation in India can be of great help in early prediction of any such indications in other countries and possibilities of the third wave in India as well. It is essential to understand the impact of variant strains in the perspective of the rise in daily cases during the second wave – Whether the rise in cases witnessed is due to the reinfections or the surge is dominated by emergence of mutants/variants and reasons for the same. Overall objective of this study is to predict early epidemiological indicators which can potentially lead to COVID-19 third wave in India. Methodology: We analyzed both the first and second waves of COVID-19 in India and using the data of India’s SARS-CoV-2 genomic sequencing, we segregated the impact of the Older Variant (OV) and the other major variants (VOI / VOC).  Applying Kermack–McKendrick SIR model to the segregated data progression of the epidemic in India was plotted in the form of proportion of people infected. An equation to explain herd immunity thresholds was generated and further analyzed to predict the possibilities of the third wave. Results: Considerable difference in ate of progression of the first and second wave was seen. The study also ascertains that the rate of infection spread is higher in Delta variant and is expected to have a higher threshold (>2 times) for herd immunity as compared to the OV. Conclusion: Likelihood of the occurrence of the third wave seems unlikely based on the current analysis of the situation, however the possibilities cannot be ruled out. Understanding the epidemiological details of the first and second wave helped in understanding the focal points responsible for the surge in cases during the second wave and has given further insight into the future.

scholarly journals A narrative review on HPV vaccination among boys and men

2020 ◽  
pp. 9-12
Author(s):  
Vinod K Ramani ◽  
Radheshyam Naik
Keyword(s):  
Hpv Vaccine ◽  
Hpv Vaccination ◽  
Herd Immunity ◽  
Population Level ◽  
Hpv Infection ◽  
Level Control ◽  
Anogenital Warts ◽  
Indian Context ◽  
Present Generation ◽  
The Cost

Apart from cervical cancer, Human papillomavirus (HPV) infection is associated with head and neck as well as other anogenital cancers such as vulva, vagina, anus, and penis. HPV vaccine provides specific protection against the disease and its subsequent manifestations.Vaccination programs for men tend to improve population-level control of HPV infection and directly prevent HPV related disease such as anogenital warts and oropharyngeal cancers in males. HPV vaccine does not treat existing infection or lesions/cancer and is intended for individuals before initiation fo sexual activity or any other form of exposure to HPV.Many programs across the globe do not include vaccination for boys because of the cost and little recognition of the emerging epidemic of HPV associated cancers in men. In the Indian context, as screening is not feasible for non-cervical HPV associated cancers, its incidence mostly among men will continue to rise until the present generation of vaccinated adolescents reaches their middle-age.Vaccination will reduce transmission rates and increase herd immunity. This in-turn, will prevent not just cervical cancers but also other HPV-associated malignancies among men and women.

scholarly journals Epidemiological impact of SARS-CoV-2 vaccination: mathematical modeling analyses

2020 ◽  
Author(s):  
Monia Makhoul ◽  
Houssein H. Ayoub ◽  
Hiam Chemaitelly ◽  
Shaheen Seedat ◽  
Ghina R Mumtaz ◽  
...  
Keyword(s):  
Decision Making ◽  
Disease Progression ◽  
Vaccine Development ◽  
Severe Disease ◽  
Herd Immunity ◽  
Social Contact ◽  
Population Level ◽  
Contact Rate ◽  
Disease Case ◽  
Vaccine Impact

AbstractBackgroundSeveral SARS-CoV-2 vaccine candidates are currently in the pipeline. This study aims to inform SARS-CoV-2 vaccine development, licensure, decision-making, and implementation by determining key preferred vaccine product characteristics and associated population-level impact.MethodsVaccination impact was assessed at various efficacies using an age-structured mathematical model describing SARS-CoV-2 transmission and disease progression, with application for China.ResultsA prophylactic vaccine with efficacy against acquisition (VES) of ≥70% is needed to eliminate this infection. A vaccine with VES <70% will still have a major impact, and may control the infection if it reduces infectiousness or infection duration among those vaccinated who acquire the infection, or alternatively if supplemented with a moderate social-distancing intervention (<20% reduction in contact rate), or complemented with herd immunity. Vaccination is cost-effective. For a vaccine with VES of 50%, number of vaccinations needed to avert one infection is only 2.4, one severe disease case is 25.5, one critical disease case is 33.2, and one death is 65.1. Gains in effectiveness are achieved by initially prioritizing those ≥60 years. Probability of a major outbreak is virtually zero with a vaccine with VES ≥70%, regardless of number of virus introductions. Yet, an increase in social contact rate among those vaccinated (behavior compensation) can undermine vaccine impact.ConclusionsEven a partially-efficacious vaccine can offer a fundamental solution to control SARS-CoV-2 infection and at high cost-effectiveness. In addition to the primary endpoint on infection acquisition, developers should assess natural history and disease progression outcomes and/or proxy biomarkers, since such secondary endpoints may prove critical in licensure, decision-making, and vaccine impact.

A Preliminary Evaluation of a Prototype Western Blot Confirmatory Test Kit for Syphilis

1994 ◽  
Vol 5 (6) ◽  
pp. 409-414 ◽  
Author(s):  
H Young ◽  
P J Walker ◽  
D Merry ◽  
A Mifsud
Keyword(s):  
Western Blot ◽  
False Positive ◽  
High Sensitivity ◽  
High Specificity ◽  
Confirmatory Test ◽  
Preliminary Evaluation ◽  
Serological Tests ◽  
Western Blot Test ◽  
Specificity And Sensitivity ◽  
Test Kit

A prototype Western blot kit was evaluated as a confirmatory test for syphilis using 131 sera characterized by other serological tests for syphilis. There were 114 treponemal sera (including 94 cases of early syphilis, 83 of which were untreated) and 17 non-treponemal problem sera (11 gave false positive reactions on screening with the TmpA recombinant antigen enzyme immunoassay (EIA), 3 gave false positive fluorescent treponemal antibody absorbed (FTA-abs) tests, and 3 false positive Captia Syphilis G EIA results). Based on the manufacturer's criteria of reactivity in multiple bands for designating a positive result the Western blot test gave a sensitivity of 99.1% (113/114) and a specificity of 88.2% (15/17) when indeterminate reactions were scored positive and 98.2% (112/114) and 100% (17/17) when indeterminate reactions were scored negative. Sensitivity was high in both treated and untreated infection. Corresponding sensitivities for the TPHA and FTA-abs when equivocal reactions were scored negative were 97.5% (111/114) and 99.1% (113/114). The high sensitivity of the FTA-abs in this study is probably due to the large number of untreated primary infections. Our results with the Western blot, confirm earlier studies using ‘in-house’ test systems and, support a role for a commercial Western blot test in the confirmatory diagnosis of syphilis. Further studies are required to confirm the high specificity and sensitivity of the kit in a larger series including a wider variety of non-treponemal cases as well as patients with untreated and treated infection.

scholarly journals Epidemiological Impact of SARS-CoV-2 Vaccination: Mathematical Modeling Analyses

Vaccines ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 668 ◽  
Author(s):  
Monia Makhoul ◽  
Houssein H. Ayoub ◽  
Hiam Chemaitelly ◽  
Shaheen Seedat ◽  
Ghina R. Mumtaz ◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Vaccine Development ◽  
Severe Disease ◽  
Herd Immunity ◽  
Social Contact ◽  
Population Level ◽  
Contact Rate ◽  
Disease Case ◽  
Major Outbreak ◽  
Vaccine Impact

This study aims to inform SARS-CoV-2 vaccine development/licensure/decision-making/implementation, using mathematical modeling, by determining key preferred vaccine product characteristics and associated population-level impacts of a vaccine eliciting long-term protection. A prophylactic vaccine with efficacy against acquisition (VES) ≥70% can eliminate the infection. A vaccine with VES <70% may still control the infection if it reduces infectiousness or infection duration among those vaccinated who acquire the infection, if it is supplemented with <20% reduction in contact rate, or if it is complemented with herd-immunity. At VES of 50%, the number of vaccinated persons needed to avert one infection is 2.4, and the number is 25.5 to avert one severe disease case, 33.2 to avert one critical disease case, and 65.1 to avert one death. The probability of a major outbreak is zero at VES ≥70% regardless of the number of virus introductions. However, an increase in social contact rate among those vaccinated (behavior compensation) can undermine vaccine impact. In addition to the reduction in infection acquisition, developers should assess the natural history and disease progression outcomes when evaluating vaccine impact.

scholarly journals Application of a fast and cost-effective ‘three-in-one’ MMR ELISA as a tool for surveying anti-MMR humoral immunity: the Hungarian experience

2020 ◽  
Vol 148 ◽  
Author(s):  
K. Böröcz ◽  
Z. Csizmadia ◽  
Á. Markovics ◽  
N. Farkas ◽  
J. Najbauer ◽  
...  
Keyword(s):  
Humoral Immunity ◽  
Low Cost ◽  
Herd Immunity ◽  
Reference Method ◽  
Population Level ◽  
Cost Effective ◽  
Published Data ◽  
Mmr Vaccine ◽  
Igg Antibody ◽  
Automated Platform

Abstract In Hungary, between February 2017 and July 2019, 70 confirmed measles cases were reported, raising questions about the adequacy of population-level immunity. Although the assumed vaccination coverage is ≥99%, in a recent study, we detected potential gaps in the anti-measles humoral immunity. In Hungary, according to a decree by the Ministry of Public Welfare, beginning from 2021, the healthcare provider should conduct a serosurvey of anti-measles protection levels of healthcare professionals. To facilitate the compliance with this requirement, we developed a quick ‘three-in-one’ or ‘triple’ MMR (measles, mumps and rubella) indirect ELISA (IgG); an assay format that is currently not available commercially. High throughput applicability of the ‘three-in-one’ ELISA was verified using 1736 sera from routine laboratory residual samples, using an automated platform (Siemens BEP 2000 Advance). Assay verification was performed by comparing the full antigen repertoire-based ‘target’ assay with in-house ‘control’ assays using recombinant viral antigen coatings, and by validated commercially available kits. Indirect immunofluorescence was used as an independent reference method. Data were analysed using OriginLab, IBM SPSS, RStudio and MedCalc. In case of measles, we combined our current results with previously published data (Ntotal measles = 3523). Evaluation of anti-mumps and anti-rubella humoral antibody levels was based on the measurement of 1736 samples. The lowest anti-measles seropositivity (79.3%) was detected in sera of individuals vaccinated between 1978 and 1987. Considering the antigen-specific seropositivity ratios of all samples measured, anti-measles, -mumps and -rubella IgG antibody titres were adequate in 89.84%, 91.82% and 92.28%, respectively. Based on the virus-specific herd immunity threshold (HIT) values (HITMeasles = 92–95%, HITMumps = 75–86%, HITRubella = 83–86), it can be stated that regarding anti-measles immunity, certain age clusters of the population may have inadequate levels of humoral immunity. Despite the potential gaps in herd immunity, the use of MMR vaccine remains an effective and low-cost approach for the prevention of measles, mumps and rubella infections.

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