Seroprevalence of anti-SARS-CoV-2 antibodies in Japanese COVID-19 patients

Characterization of antibody response to SARS-CoV-2 Orf8 from three waves of COVID-19 outbreak in Thailand

A dynamic of virus adaptation and a mass vaccination campaign could significantly reduce the severity of clinical manifestations of COVID-19 and transmission. Hence, COVID-19 may become an endemic disease globally. Moreover, mass infection as the COVID-19 pandemic progressed affected the serology of the patients as a result of virus mutation and vaccination. Therefore, a need exists to acquire accurate serological testing to monitor the emergence of new outbreaks of COVID-19 to promptly prevent and control the disease spreading. In this study, the anti-Orf8 antibodies among samples collected in Thailand's first, fourth, and fifth waves of COVID-19 outbreaks compared with pre-epidemic sera were determined by indirect ELISA. The diagnostic sensitivity and specificity of the anti-Orf8 IgG ELISA for COVID-19 samples from the first, fourth, and fifth waves of outbreaks was found to be 100% compared with pre-epidemic sera. However, the diagnostic sensitivity and specificity of the anti-Orf8 IgG ELISA for a larger number of patient samples and controls from the fifth wave of outbreaks which were collected on day 7 and 14 after an RT-PCR positive result were 58.79 and 58.44% and 89.19 and 58.44%, respectively. Our data indicated that some of the controls might have antibodies from natural past infections. Our study highlighted the potential utility of anti-Orf8 IgG antibody testing for seroprevalence surveys but still warrants further investigations.

Performance evaluation of the Ortho VITROS SARS-CoV-2 Spike-Specific Quantitative IgG test by comparison with the surrogate virus neutralizing antibody test and clinical assessment

BACKGROUND

Despite the worldwide campaigns of COVID-19 vaccinations, the pandemic is still a major medical and social problem. The Ortho VITROS SARS-CoV-2 spike-specific quantitative IgG (VITROS S-IgG) assay has been developed to assess neutralizing antibody (NT antibody) against SARS-CoV-2 spike (S) antibodies. However, it has not been evaluated in Japan, where the total cases and death toll are lower than the rest of the world.

METHODS

The clinical performance of VITROS S-IgG was evaluated by comparing with the NT antibody levels measured by the surrogate virus neutralizing antibody test (sVNT). A total of 332 serum samples from 188 individuals were used. Of these, 219 samples were from 75 COVID-19 patients: 96 samples from 20 severe/critical cases (Group S), and 123 samples from 55 mild/moderate cases (Group M). The remaining 113 samples were from 113 healthcare workers who had received 2 doses of the BNT162b2 vaccine.

RESULTS

VITROS S-IgG showed good correlation with the cPass sVNT assay (Spearman rho = 0.91). Both VITROS S-IgG and cPass sVNT showed significantly higher plateau levels of antibodies in Group S compared to Group M. Regarding the humoral immune responses after BNT162b2 vaccination, individuals who were negative for SARS-CoV-2 nucleocapsid (N)-specific antibodies had statistically lower titers of both S-IgG and sVNT compared to individuals with a history of COVID-19 and individuals who were positive for N-specific antibodies without history of COVID-19. In individuals who were positive for N-specific antibodies, S-IgG and sVNT titers were similar to individuals with a history of COVID-19.

CONCLUSIONS

Although the automated quantitative immunoassay VITROS S-IgG showed a reasonable correlation with sVNT antibodies, there is some discrepancy between Vitros S-IgG and cPass sVNT in milder cases. Thus, VITROS S-IgG can be a useful diagnostic tool in assessing the immune responses to vaccination and herd immunity. However, careful analysis is necessary to interpret the results.

Validity and reliability of immunochromatographic IgM/IgG rapid tests for COVID-19 salivary diagnosis

OBJECTIVES

To assess the accuracy of three immunochromatographic rapid tests for salivary detection of immunoglobulin M (IgM) and immunoglobulin G (IgG) antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigens and the reliability of these tests comparing saliva with plasma samples.

MATERIALS AND METHODS

Plasma and saliva samples from 62 patients diagnosed with coronavirus disease 2019 (COVID-19) and 20 healthy volunteers were assayed. IgM/IgG antibody against SARS-COV-2 was detected using three immunochromatographic rapid tests and compared with real-time reverse transcription-polymerase chain reaction (qRT-PCR).

RESULTS

The tests' overall accuracy for detecting anti-SARS-CoV-2 antibodies ranged from 75.6 to 79.3 for saliva and 86.6-87.8 for plasma tests. The sensitivity of saliva and plasma tests increased with the severity of COVID-19 signs and symptoms. The chance of a positive plasma test in participants with a positive qRT-PCR test was 2.27 greater than a positive saliva test.

CONCLUSIONS

Although rapid immunochromatographic tests are more accurate using plasma than saliva, which was expected considering its original use, our findings support the use of saliva as a straightforward supplementary method to assess seroconversion in patients with COVID-19, with important sensitivity and sensibility, especially in severe and critical cases.

Seroprevalence of SARS-CoV-2 on health professionals via Bayesian estimation: a Brazilian case study before and after vaccines

The increasing number of COVID-19 infections brought by the current pandemic has encouraged the scientific community to analyze the seroprevalence in populations to support health policies. In this context, accurate estimations of SARS-CoV-2 antibodies based on antibody tests metrics (e.g., specificity and sensitivity) and the study of population characteristics are essential. Here, we propose a Bayesian analysis using IgA and IgG antibody levels through multiple scenarios regarding data availability from different information sources to estimate the seroprevalence of health professionals in a Northeastern Brazilian city: no data available, data only related to the test performance, data from other regions. The study population comprises 432 subjects with more than 620 collections analyzed via IgA/IgG ELISA tests. We conducted the study in pre- and post-vaccination campaigns started in Brazil. We discuss the importance of aggregating available data from various sources to create informative prior knowledge. Considering prior information from the USA and Europe, the pre-vaccine seroprevalence means are 8.04% and 10.09% for IgG and 7.40% and 9.11% for IgA. For the post-vaccination campaign and considering local informative prior, the median is 84.83% for IgG, which confirms a sharp increase in the seroprevalence after vaccination. Additionally, stratification considering differences in sex, age (younger than 30 years, between 30 and 49 years, and older than 49 years), and presence of comorbidities are provided for all scenarios.

Inferring the true number of SARS-CoV-2 infections in Japan

Introduction

In Japan, as of December 31, 2021, more than 1.73 million laboratory-confirmed cases have been reported. However, the actual number of infections is likely to be under-ascertained due to the epidemiological characteristics such as mild and subclinical infections and limited testing availability in the early days of the pandemic. In this study, we infer the true number of infections in Japan between January 16, 2020, and December 31, 2021, using a statistical modelling framework that combines data on reported cases and fatalities.

Methods

We used reported COVID-19 deaths and age-specific infection fatality ratios (IFR) to impute the true number of infections. Estimates of IFR were informed from published studies and were adjusted to reflect the effects of pharmaceutical interventions, mass vaccination, and evolving variants. To account for the uncertainty in IFR, we sampled values from relevant distributions.

Results

We estimated that as of December 31, 2021, 3.07 million (CrI: 2.05–4.24 million) people had been infected in Japan, which is 1.77 times higher than the 1.73 million reported cases. Our meta-analysis confirmed that these findings were consistent with the intermittent seroprevalence studies conducted in Japan.

Conclusions

We have estimated that a substantial number of COVID-19 infections in Japan were unreported, particularly in adults. Our approach provides a more realistic assessment of the true underlying burden of COVID-19. The results of this study can be used as fundamental components to strengthen population health control and surveillance measures.

The SARS-CoV-2 pandemic in Germany may represent the sum of a large number of local but independent epidemics each initiated by individuals aged 10 - 19 years, middle aged males, or elderly individuals

Many epidemiological aspects of the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) pandemics, particularly those affecting children, are still sparsely elucidated. Data on the first pandemic phase during the year 2020 indicated that children might serve as a virus reservoir. We now analyzed data on more than 530 000 SARS‐CoV‐2 polymerase chain reaction (PCR) and 12 503 anti‐SARS‐CoV‐2 antibody tests performed in the west of Germany until Week 4 of 2021. We show that children of at least 10 years of age may play a prominent role in the pandemic showing highest PCR‐positive rates in the first (Weeks 28–35), second (Weeks 42–48), and third wave (Week 50 of 2020–Week 2 2021) of the second pandemic phase, although the waves were not mainly initiated by children. The waves' kinetics differed even in nearby cities. Low PCR‐positive rates were confined to areas of lower population density. PCR‐positive rates were higher among middle‐aged males compared with women and among very old females compared with males. From Week 25, seroprevalence rates slowly increased to 50%, indicating ongoing virus activity. In conclusion, the SARS‐CoV‐2 pandemics is characterized by many local but interacting epidemics, initiated and driven by different social groups. Children may not be the main initiators of virus spreading but older children may significantly affect the course of the pandemic. High population density is associated with higher SARS‐CoV‐2 incidence.

A Case of ST-Elevation Acute Myocardial Infarction in a Nonhospitalized Patient with SARS-CoV-2 Pneumonia: Treatment with Primary Percutaneous Coronary Intervention

We experienced a case of primary percutaneous coronary intervention for ST-elevation myocardial infarction (STEMI) with coronavirus disease 2019 (COVID-19) using appropriate infection prevention protocol. However, recanalization was difficult due to severe coagulopathy. Further researches are needed to clarify optimal treatment for STEMI in patients with COVID-19.