scholarly journals Large-scale cross-sectional seroepidemiologic study of COVID-19 in Japan: Acquisition of herd immunity and the vaccines' efficacy

2022 ◽  
Author(s):  
Zhenxiao Ren ◽  
Mitsuhiro Nishimura ◽  
Lidya Handayani Tjan ◽  
Koichi Furukawa ◽  
Yukiya Kurahashi ◽  
...  
Keyword(s):  
Large Scale ◽  
Herd Immunity ◽  
Vaccination Rate ◽  
Enzyme Linked Immunosorbent Assay ◽  
Cross Sectional ◽  
Neutralizing Activity ◽  
Polymerase Chain ◽  
Hyogo Prefecture ◽  
Seroepidemiologic Study ◽  
Roll Out

Background: The COVID-19 pandemic situation has been changing drastically worldwide due to the continuous appearance of SARS-CoV-2 variants and the roll-out of mass vaccination. Periodic cross-sectional studies during the surge of COVID-19 cases is essential to elucidate the pandemic situation. Methods: Sera of 1,000 individuals who underwent a health check-up in Hyogo Prefecture Health Promotion Association clinics in Japan were collected in August and December 2021. Antibodies against SARS-CoV-2 N and S antigens were detected in the sera by an electrochemiluminescence immunoassay (ECLIA) and an enzyme-linked immunosorbent assay (ELISA), respectively. The sera's neutralization activities for the conventional SARS-CoV-2 (D614G), Delta, and Omicron variants were measured. Results: The seropositive rates for the antibody against N antigen were 2.1% and 3.9% in August and December 2021 respectively, demonstrating a Delta variant endemic during that time; the actual infection rate was approximately twofold higher than the rate estimated based on the polymerase chain reaction (PCR)-based diagnosis. The anti-S seropositive rate was 38.7% in August and it reached 90.8% in December, in concordance with the vaccination rate in Japan. In the December cohort, 78.7% of the sera showed neutralizing activity against the Delta variant, whereas that against the Omicron was much lower at 36.6%. Conclusions: These analyses revealed that herd immunity against SARS-CoV-2 including the Delta variant was established in December 2021, leading to convergence of the variants. The low neutralizing activity against the Omicron variant suggests the need for the further promotion of the prompt three-dose vaccination to overcome this variant's imminent 6th wave in Japan.

scholarly journals Large-scale seroepidemiologic surveillance of COVID-19 - Cross-sectional study in Hyogo prefecture of Japan in August, 2021

2021 ◽  
Author(s):  
Zhenxiao Ren ◽  
Koichi Furukawa ◽  
Mitsuhiro Nishimura ◽  
Yukiya Kurahashi ◽  
Silvia Sutandhio ◽  
...  
Keyword(s):  
Large Scale ◽  
Cross Sectional Study ◽  
Vaccination Rate ◽  
Mass Vaccination ◽  
Enzyme Linked Immunosorbent Assay ◽  
Cross Sectional ◽  
Pcr Diagnosis ◽  
Positive Rate ◽  
Hyogo Prefecture ◽  
Roll Out

The situation of the COVID-19 pandemic in Japan is drastically changing in the 2nd year, 2021, due to the appearance of SARS-CoV-2 variants of concern and the roll-out of mass vaccination. In addition to PCR diagnosis, periodic seroepidemiologic surveillance is important to analyze the epidemic situation. In this study, we analyzed the rate of seropositivity for the SARS-CoV-2 N and S antigens in Hyogo prefecture, Japan in August 2021. Sera collected from people who received a health check-up in a clinic of the Hyogo Prefecture Health Promotion Association were subjected to analysis of reactivity to the SARS-CoV-2 N and S antigens by electrochemiluminescence immunoassay (ECLIA) and enzyme-linked immunosorbent assay (ELISA), respectively. For a total 1,000 sera, the positive rates to N and S antigens were 2.1% and 38.7%, respectively. The infectious rate estimated by serological analysis based on the presence of the anti-N antibody was 2.5-fold higher than the value reported based on PCR-based analysis, and it increased five-fold compared to the rate determined by our previous seroepidemiologic study in October, 2020. The anti-S positive rate was almost consistent with the vaccination rate in this area. The observed high anti-S antibody level in the seropositive population may indicate that the mass vaccination in Japan is being performed smoothly at this time point, although the infectious rate has also increased.

scholarly journals SARS-CoV-2 IgG Antibodies Seroprevalence and Sera Neutralizing Activity in MEXICO: A National Cross-Sectional Study during 2020

2021 ◽  
Vol 9 (4) ◽  
pp. 850
Author(s):  
José Esteban Muñoz-Medina ◽  
Concepción Grajales-Muñiz ◽  
Angel Gustavo Salas-Lais ◽  
Larissa Fernandes-Matano ◽  
Constantino López-Macías ◽  
...  
Keyword(s):  
Immunosorbent Assay ◽  
Neutralizing Antibodies ◽  
Herd Immunity ◽  
Cross Sectional Study ◽  
Molecular Techniques ◽  
Diagnostic Methods ◽  
Molecular Diagnostic ◽  
Enzyme Linked Immunosorbent Assay ◽  
Cross Sectional ◽  
Neutralizing Activity

Until recently, the incidence of COVID-19 was primarily estimated using molecular diagnostic methods. However, the number of cases is vastly underreported using these methods. Seroprevalence studies estimate cumulative infection incidences and allow monitoring of transmission dynamics, and the presence of neutralizing antibodies in the population. In February 2020, the Mexican Social Security Institute began conducting anonymous unrelated sampling of residual sera from specimens across the country, excluding patients with fever within the previous two weeks and/or patients with an acute respiratory infection. Sampling was carried out weekly and began 17 days before Mexico’s first officially confirmed case. The 24,273 sera obtained were analyzed by chemiluminescent-linked immunosorbent assay (CLIA) IgG S1/S2 and, later, positive cases using this technique were also analyzed to determine the rate of neutralization using the enzyme-linked immunosorbent assay (ELISA). We identified 40 CLIA IgG positive cases before the first official report of SARS-CoV-2 infection in Mexico. The national seroprevalence was 3.5% in February and 33.5% in December. Neutralizing activity among IgG positives patients during overall study period was 86.1%. The extent of the SARS-CoV-2 infection in Mexico is 21 times higher than that reported by molecular techniques. Although the general population is still far from achieving herd immunity, epidemiological indicators should be re-estimated based on serological studies of this type.

scholarly journals SARS-CoV-2 infection is at herd immunity in the majority segment of the population of Qatar

2021 ◽  
Author(s):  
Mohamed H Al-Thani ◽  
Elmoubasher Farag ◽  
Roberto Bertollini ◽  
Hamad Eid Al Romaihi ◽  
Sami Abdeen ◽  
...  
Keyword(s):  
Total Population ◽  
Herd Immunity ◽  
Geographic Location ◽  
Population Based ◽  
Infection Prevalence ◽  
Cross Sectional ◽  
Previous Infection ◽  
Current Infection ◽  
Polymerase Chain ◽  
Population Based Survey

Abstract Background Qatar experienced a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) epidemic that disproportionately affected the craft and manual worker (CMW) population who comprise 60% of the total population. This study aimed to assess ever and/or current infection prevalence in this population. Methods A cross-sectional population-based survey was conducted during July 26-September 09, 2020 to assess both anti-SARS-CoV-2 positivity through serological testing and current infection positivity through polymerase chain reaction (PCR) testing. Associations with antibody and PCR positivity were identified through regression analyses. Results Study included 2,641 participants, 69.3% of whom were <40 years of age. Anti-SARS-CoV-2 positivity was 55.3% (95% CI: 53.3-57.3%) and was significantly associated with nationality, geographic location, educational attainment, occupation, and previous infection diagnosis. PCR positivity was 11.3% (95% CI: 9.9-12.8%) and was significantly associated with nationality, geographic location, occupation, contact with an infected person, and reporting two or more symptoms. Infection positivity (antibody and/or PCR positive) was 60.6% (95% CI: 58.6-62.5%). The proportion of antibody-positive CMWs that had a prior SARS-CoV-2 diagnosis was 9.3% (95% CI: 7.9-11.0%). Only seven infections were ever severe and one was ever critical—an infection severity rate of 0.5% (95% CI: 0.2-1.0%). Conclusions Six in every 10 CMWs have been infected, suggestive of reaching the herd immunity threshold. Infection severity was low with only one in every 200 infections progressing to be severe or critical. Only one in every 10 infections had been previously diagnosed suggestive of mostly asymptomatic or mild infections.

SARS-CoV-2 Herd Immunity of the Kyrgyz Population in 2021

2021 ◽  
Author(s):  
Anna Y. Popova ◽  
Omor T. Kasymov ◽  
Vyacheslav Y. Smolenski ◽  
Вячеслав Смирнов ◽  
Svetlana A. Egorova ◽  
...  
Keyword(s):  
Randomized Study ◽  
Herd Immunity ◽  
Statistical Processing ◽  
Cloud Service ◽  
Asymptomatic Infection ◽  
Enzyme Linked Immunosorbent Assay ◽  
Pasteur Institute ◽  
Cross Sectional ◽  
Saint Petersburg ◽  
Kyrgyz Population

Abstract Background. In the fight against coronavirus infection, an important direction is control of herd immunity to the pathogen. SARS-CoV-2 herd immunity is formed naturally as a result of manifest or asymptomatic infection, or artificially as a result of vaccination Aim: To assess the SARS-CoV-2 herd immunity status of the Kyrgyz population. Materials and methods. A cross-sectional, randomized study of SARS-CoV-2 herd immunity was carried out according to a program developed by Rospotrebnadzor, with the participation of the Saint Petersburg Pasteur Institute, taking into account WHO recommendations. In all study stages cloud service (internet) technologies were used. The ethics committees of the Preventive Medicine Association (Kyrgyzstan) and the Saint Petersburg Pasteur Institute (Russia) approved the study. A total of 9,471 volunteers were selected, representing 0.15% (95% CI 0.14-0.15) of the total population. They were randomized according to age and region. Antibodies (Abs) to the nucleocapsid antigen (Nag) were determined by enzyme-linked immunosorbent assay (ELISA) of volunteer blood plasma. For vaccinated individuals, Abs to the SARS-CoV-2 receptor-binding domain antigen (RBDag) were determined. Statistical processing of the results was carried out using Excel 2010 and other programs. Differences were designated as statistically significant at p<0.05. Results. The seroprevalence of the general population was 48.7% (95% CI 47.7-49.7), with a maximum in the group of '60-69 year old' (59.2% (56.6-61.7)) and a minimum in the group '1-17 y.o.' (32.7% (95 CI 29.4-36.1)). The largest proportion seropositive was found in the Chui region (51.3% (95% CI 47.9-54.8)). The lowest was in Osh city (38.1% (95 CI 32.6-43.9)). The maximum seropositivity was detected among healthcare workers (57.1% (95% CI 55.4-58.8); the minimum was noted among artists (38.6% (95% CI 26.0-52.4)). Asymptomatic SARS-CoV-2 positivity was 79.1% (96% CI 77.9-80.3). Vaccination with Sputnik V, EpiVacCorona, or Sinopharm formed comparable levels of immunity. Conclusions. The herd immunity to SARS-CoV-2 Nag is 48.75% (95% CI 47.7-49.7), and the overall immunity (Nag + RBDag) is 57%.

scholarly journals Will the Large-scale Vaccination Succeed in Containing the COVID-19 Epidemic and How Soon?

2021 ◽  
Author(s):  
Shilei Zhao ◽  
Tong Sha ◽  
Yongbiao Xue ◽  
Chung-I Wu ◽  
Hua Chen
Keyword(s):  
United States Of America ◽  
Vaccine Efficacy ◽  
Large Scale ◽  
Herd Immunity ◽  
Vaccination Rate ◽  
Epidemic Dynamics ◽  
Intervention Measures ◽  
Vaccination Scheme ◽  
Mutant Strains ◽  
Promising Solution

The availability of vaccines provides a promising solution to containing the COVID-19 pandemic. Here, we develop an epidemiological model to quantitatively analyze and predict the epidemic dynamics of COVID-19 under vaccination. The model is applied to the daily released numbers of confirmed cases of Israel and United States of America to explore and predict the trend under vaccination based on their current epidemic status and intervention measures. For Israel, of which 53.83% of the population was fully vaccinated, under the current intensity of NPIs and vaccination scheme, the pandemic is predicted to end between May 14, 2021 to May 16, 2021 depending on an immunity duration between 180 days and 365 days; Assuming no NPIs after March 24, 2021, the pandemic will ends later, between July 4, 2021 to August 26, 2021. For USA, if we assume the current vaccination rate (0.268% per day) and intensity of NPIs, the pandemic will end between February 3, 2022 and August 17, 2029 depending on an immunity duration between 180 days and 365 days. However, assuming an immunity duration of 180 days and with no NPIs, the pandemic will not end, and instead reach an equilibrium state with a proportion of the population remaining actively infected. Overall the daily vaccination rate should be chosen according to the vaccine efficacy and the immunity duration to achieve herd immunity. In some situations, vaccination alone cannot stop the pandemic, and NPIs are necessary both to supplement vaccination and accelerate the end of the pandemic. Considering that vaccine efficacy and duration of immunity may be reduced for new mutant strains, it is necessary to remain cautiously optimistic about the prospect of the pandemic under vaccination.

scholarly journals Seroprevalence of SARS-CoV-2 infection in the craft and manual worker population of Qatar

2020 ◽  
Author(s):  
Mohamed H. Al-Thani ◽  
Elmoubasher Farag ◽  
Roberto Bertollini ◽  
Hamad Eid Al Romaihi ◽  
Sami Abdeen ◽  
...  
Keyword(s):  
Total Population ◽  
Herd Immunity ◽  
Geographic Location ◽  
Population Based ◽  
Cross Sectional ◽  
Manual Worker ◽  
Previous Infection ◽  
Current Infection ◽  
Polymerase Chain ◽  
Population Based Survey

ABSTRACTBackgroundQatar experienced a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) epidemic that disproportionately affected the craft and manual worker (CMW) population who comprise 60% of the total population. This study aimed to assess the proportions of ever and/or current infection in this population.MethodsA cross-sectional population-based survey was conducted during July 26-September 09, 2020 to assess both anti-SARS-CoV-2 positivity through serological testing and polymerase chain reaction (PCR) positivity through PCR testing. Associations with antibody and PCR positivity were identified through regression analyses.ResultsStudy included 2,641 participants, 69.3% of whom were <40 years of age. Anti-SARS-CoV-2 positivity was estimated at 55.3% (95% CI: 53.3-57.3%) and was significantly associated with nationality, geographic location, educational attainment, occupation, presence of symptoms in the two weeks preceding the survey, and previous infection diagnosis. PCR positivity was assessed at 11.3% (95% CI: 9.9-12.8%) and was significantly associated with geographic location, contact with an infected person, and reporting two or more symptoms. Infection positivity (antibody and/or PCR positive) was assessed at 60.6% (95% CI: 9.9-12.8%). The proportion of antibody-positive CMWs that had a prior SARS-CoV-2 diagnosis was 9.3% (95% CI: 7.9-11.0%). Only seven infections were ever severe and one was ever critical—an infection severity rate of 0.5% (95% CI: 0.2-1.0%).ConclusionsSix in every 10 CMWs have been infected, suggestive of reaching the herd immunity threshold. Infection severity was low with only one in every 200 infections progressing to be severe or critical. Only one in every 10 infections had been previously diagnosed suggestive of mostly asymptomatic or minimally mild infections.

scholarly journals Joint CBC-ICT Interpretation for the pre-surgical screening of COVID 19 asymptomatic cases: A cross-sectional study

2020 ◽  
Author(s):  
Tanzeel Imran ◽  
Humera Altaf Naz ◽  
Hamza Khan ◽  
Ali Haider Bangash ◽  
Laraib Bakhtiar Khan ◽  
...  
Keyword(s):  
Large Scale ◽  
Complete Blood Count ◽  
Cross Sectional Study ◽  
Future Research ◽  
Monocyte Count ◽  
Cross Sectional ◽  
Asymptomatic Patients ◽  
Screening Strategies ◽  
Polymerase Chain ◽  
Limited Health

AbstractBackgroundOn 26th, February 2020, first cases of COVID 19 were confirmed in Pakistan. Since then, surgeries were halted in a bid to prevent transmission. However, since such a long halt is infeasible, a general protocol of screening the carriers, especially asymptomatic carries, is a dire need of time. The objective of our study is to propose an economically feasible protocol of COVID 19 screening. Simple but effective screening strategies can help to restore the workings of hospital surgical departments.MethodsWe analyzed the clinical data of patients turning up for elective surgeries at the Rawal General Hospital (RGH), Islamabad from the 24th of March to the 15th of May, 2020. Asymptomatic patients with negative COVID 19 contact and travel histories were screened with COVID 19 Immunochromatography (ICT) IgM / IgG Ab Test. Complete blood count (CBC) was done and interpreted in conjunction with the ICT results.Results39 patients with a mean age of 49 years were studied. The result of ICT for COVID-19 was positive in 9 cases (23%). The entire positive ICT patients population expressed significantly lower lymphocyte count (p<0.01); 8 patients had high monocyte count (p<0.05) whereas only 4 patients had a combined high neutrophil and monocyte count (P<0.05). All of these four patients with high neutrophil count were females. The combined interpretation of CBC and ICT IgM / IgG Ab Test had a high accuracy in diagnosing asymptomatic COVID-19 carriers that were later confirmed by real-time reverse transcriptase-polymerase chain reaction (rRT-PCR).ConclusionWe propose that joint CBC-ICT interpretation should be adopted on a large scale to help in the diagnoses of asymptomatic carriers as both tests are simple and inexpensive and thus suit the developing countries’ limited health budget. Future research projects should be adopted in order to assess the accuracy of the proposed protocol on a large scale.

COVID-19 Vaccine Perception in South Korea: A Web-Crawling Approach (Preprint)

2021 ◽  
Author(s):  
Hocheol Lee ◽  
Eun Bi Noh ◽  
Sung Jong Park ◽  
Hae-Kweun Nam ◽  
Tae Ho Lee ◽  
...  
Keyword(s):  
Information Needs ◽  
Herd Immunity ◽  
Economic Loss ◽  
Cross Sectional Study ◽  
Vaccination Rate ◽  
World Health ◽  
Accurate Information ◽  
Web Crawling ◽  
Cross Sectional ◽  
Negative Perception

BACKGROUND The US Center for Disease Control and Prevention and the World Health Organization emphasized vaccination against the Coronavirus disease 2019 (COVID-19) because physical distancing proved inadequate to mitigate death, illness, and massive economic loss. OBJECTIVE The purpose of this study was to investigate Korean citizens’ perceptions of vaccines by examining their views on COVID-19, their positive and negative perceptions of each vaccine, and ways to enhance policies to increase vaccine acceptance. METHODS This cross-sectional study analyzed posts on NAVER and Instagram to examine Korean citizens’ acceptance of COVID-19 vaccines. The keywords searched were “vaccine,” “AstraZeneca,” and “Pfizer.” In total 8,100 posts in NAVER and 5,291 posts in Instagram were sampled through web crawling. Morphology analysis was performed, overlapping or meaningless words were removed, sentiment analysis was implemented, and three public health professionals reviewed the results. RESULTS The findings revealed a negative perception of COVID-19 vaccines; of the words crawled, the proportion of negative words for AstraZeneca was 71.0% and for Pfizer was 56.3%. Moreover, 70.5% considered Pfizer safe, while 30.4% thought AstraZeneca safe. Among words crawled with “vaccine,” “good” ranked first, with a frequency of 312 (13.4%). Meanwhile, “side effect” ranked highest, with a frequency of 163 (18.4%) for “AstraZeneca,” but 0.6%. for “Pfizer.” With “vaccine,” positive words were more frequently used, whereas with “AstraZeneca” and “Pfizer” negative words were prevalent. CONCLUSIONS There is a negative perception of AstraZeneca and Pfizer vaccines in Korea, with one in four people refusing vaccination. To address this, accurate information needs to be shared about vaccines including AstraZeneca, and the experiences of those vaccinated. Furthermore, government communication about risk management is required to increase the AstraZeneca vaccination rate for herd immunity before the vaccine expires.

scholarly journals Validation of a SARS-CoV-2 spike protein ELISA for use in contact investigations and sero-surveillance

2020 ◽  
Author(s):  
Brandi Freeman ◽  
Sandra Lester ◽  
Lisa Mills ◽  
Mohammad Ata Ur Rasheed ◽  
Stefany Moye ◽  
...  
Keyword(s):  
Disease Burden ◽  
Large Scale ◽  
Case Fatality ◽  
Asymptomatic Infection ◽  
Cross Reactivity ◽  
Spike Protein ◽  
Enzyme Linked Immunosorbent Assay ◽  
Specific Enzyme ◽  
Cross Sectional ◽  
Contact Investigations

AbstractSince emergence of SARS-CoV-2 in late 2019, there has been a critical need to understand prevalence, transmission patterns, to calculate the burden of disease and case fatality rates. Molecular diagnostics, the gold standard for identifying viremic cases, are not ideal for determining true case counts and rates of asymptomatic infection. Serological detection of SARS-CoV-2 specific antibodies can contribute to filling these knowledge gaps. In this study, we describe optimization and validation of a SARS-CoV-2-specific-enzyme linked immunosorbent assay (ELISA) using the prefusion-stabilized form of the spike protein [1]. We performed receiver operator characteristic (ROC) analyses to define the specificities and sensitivities of the optimized assay and examined cross reactivity with immune sera from persons confirmed to have had infections with other coronaviruses. These assays will be used to perform contact investigations and to conduct large-scale, cross sectional surveillance to define disease burden in the population.

Epidemiology of Q – Fever in Flocks of Sheep in Yobe State, Nigeria

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
S. G. Adamu
Keyword(s):  
Large Scale ◽  
Q Fever ◽  
Sampling Technique ◽  
Simple Random Sampling ◽  
Enzyme Linked Immunosorbent Assay ◽  
Epidemiological Investigation ◽  
Negative Bacterium ◽  
Cross Sectional ◽  
Livestock Farmers ◽  
Male Sheep

Q-fever is a zoonotic disease caused by Coxiella burnetii, an intracellular Gram-negative bacterium. A cross sectional epidemiological study was conducted to determine the seroprevalence of Q-fever in flocks of sheep in Yobe State, Nigeria. Simple random sampling technique was used in selecting the animals. A total of 420 blood samples from sheep of various ages were tested from April, 2018 to July, 2018 for Q-fever using indirect enzyme linked immunosorbent assay (ELISA). Out of the 420 sera tested 49 (11.7%) were seeropositive for Q fever. Of the 315 females sheep tested, 39 (12.4%) were seropositive and out of 105 male sheep tested, 10 (9.5%) were seropositive. There was no significant association (p>0.05) between the sex of sheep tested for Q fever. The seroprevalence was higher in animals greater than 2 years 41 (12.1%) than in animals less than 2 years 8 (9.8%). There were no significant associations between age and infection with Q-fever even though that animal greater than 2 years showed higher prevalence than those less than 2 years. The highest seroprevalence 22 (12.3%) was recorded in Yankasa sheep, and the least seroprevalence 8(9.9%) was recorded in Uda. The seroprevalence of 19 (13.6%), 16 (11.4%) and 14 (10.0%) were recorded in Damaturu, Potiskum and Gashua zones respectively. There was no significant association (p>0.05) between the breed and location of the animals tested for Q fever infection. This study concludes that Q-fever is endemic in sheep in Yobe State. Enlightenment campaign is recommended to educate the livestock farmers, herders and the general public on the dangers of Q-fever infection. There is need for large scale epidemiological investigation of the disease in other livestock farms in the state.

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