Comparative analysis of F-18 FDG PET/CT images between scrub typhus and systemic lupus erythematosus.

This study evaluated the use of F-18 fluorodeoxyglucose (FDG) PET/CT imaging to differentiate between scrub typhus and systemic lupus erythematosus (SLE) in patients presenting with lymphadenopathy. We carried out a retrospective analysis of 18 scrub typhus patients and seven SLE patients, using various imaging parameters, including lymph node size, spleen and liver lengths, the distance between the two farthest lesions (Dmax), and assessments of glucose metabolism. On FDG PET images, we measured the maximum standardized uptake value (SUVmax) of the lymph nodes, spleen, and liver and the mean standardized uptake value (SUVmean) of the liver and spleen. The Dmax values of scrub typhus patients were significantly longer than those of SLE patients, indicating that lymphadenopathy is more generalized in the patients with scrub typhus. The SUVmax values for the lymph node, spleen, and liver were also higher in patients with scrub typhus, while the SUVmean of the liver and spleen did not differ between the two groups. This study is the first to compare FDG PET/CT images between these two conditions, suggesting the potential of this imaging modality to provide critical diagnostic distinctions.

Severe Fever with Thrombocytopenia Syndrome in South Korea, 2016-2021: Clinical Features of Severe Progression and Complications.

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infection with a high case fatality rate. The serious clinical features need to be further defined. We performed a retrospective analysis among SFTS patients in South Korea during 2016-2021 to update the current status. The basic epidemiology of all reported cases was analyzed, and the detailed clinical data of the subjects were further collected from study hospitals selected in terms of their geographic location and capability of SFTS care. Cases of SFTS were reported across the country and were greatly increased since the initial endemic phase, even under the passive surveillance system. The case fatality rate remained at approximately 16.8%. Coinfections at admission were present in 7.8% of the patients. Major complications included bleeding (15.2%), hemophagocytic lymphohistiocytosis (6.7%), bacteremia or candidemia (4.0%), and invasive pulmonary aspergillosis (1.7%). It took a median 4 days from the onset of illness to hospital admission. Rapid clinical deterioration was observed with a median 1 day for intensive care unit admission, 3 days for mechanical ventilation, 4 days for renal replacement therapy, and 5 days for death, all after the hospitalization. Multivariate analysis showed that the fatality was associated with older age, bacteremia, or candidemia during hospitalization, and the presence of several variables at admission such as fever, altered mentality, aspartate aminotransferase >200 IU/L, serum creatinine level >1.2 mg/dL, and prolonged prothrombin time and activated partial thromboplastin time. Treatment options to improve clinical outcomes are limited, despite best supportive care. Specific treatment is urgently needed to change the fatal course.

Incidence of Clostridioides difficile Infections in Republic of Korea: A Prospective Study With Active Surveillance vs. National Data From Health Insurance Review & Assessment Service.

BACKGROUND: Since the emergence of hypervirulent strains of Clostridioides difficile, the incidence of C. difficile infections (CDI) has increased significantly. METHODS: To assess the incidence of CDI in Korea, we conducted a prospective multicentre observational study from October 2020 to October 2021. Additionally, we calculated the incidence of CDI from mass data obtained from the Health Insurance Review and Assessment Service (HIRA) from 2008 to 2020. RESULTS: In the prospective study with active surveillance, 30,212 patients had diarrhoea and 907 patients were diagnosed with CDI over 1,288,571 patient-days and 193,264 admissions in 18 participating hospitals during 3 months of study period; the CDI per 10,000 patient-days was 7.04 and the CDI per 1,000 admission was 4.69. The incidence of CDI was higher in general hospitals than in tertiary hospitals: 6.38 per 10,000 patient-days (range: 3.25-12.05) and 4.18 per 1,000 admissions (range: 1.92-8.59) in 11 tertiary hospitals, vs. 9.45 per 10,000 patient-days (range: 5.68-13.90) and 6.73 per 1,000 admissions (range: 3.18-15.85) in seven general hospitals. With regard to HIRA data, the incidence of CDI in all hospitals has been increasing over the 13-year-period: from 0.3 to 1.8 per 10,000 patient-days, 0.3 to 1.6 per 1,000 admissions, and 6.9 to 56.9 per 100,000 population, respectively. CONCLUSION: The incidence of CDI in Korea has been gradually increasing, and its recent value is as high as that in the United State and Europe. CDI is underestimated, particularly in general hospitals in Korea.

Magnitude and Duration of Serum Neutralizing Antibody Titers Induced by a Third mRNA COVID-19 Vaccination against Omicron BA.1 in Older Individuals.

BACKGROUND: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant (B.1.1.529) is dominating coronavirus disease 2019 (COVID-19) worldwide. The waning protective effect of available vaccines against the Omicron variant is a critical public health issue. This study aimed to assess the impact of the third COVID-19 vaccination on immunity against the SARS-CoV-2 Omicron BA.1 strain in older individuals. MATERIALS AND METHODS: Adults aged ≥60 years who had completed two doses of the homologous COVID-19 vaccine with either BNT162b2 (Pfizer/BioNTech, New York, NY, USA, BNT) or ChAdOx1 nCoV (SK bioscience, Andong-si, Gyeongsangbuk-do, Korea, ChAd) were registered to receive the third vaccination. Participants chose either BNT or mRNA-1273 (Moderna, Norwood, MA, USA, m1273) mRNA vaccine for the third dose and were categorized into four groups: ChAd/ChAd/BNT, ChAd/ChAd/m1273, BNT/BNT/BNT, and BNT/BNT/m1273. Four serum specimens were obtained from each participant at 0, 4, 12, and 24 weeks after the third dose (V1, V2, V3, and V4, respectively). Serum-neutralizing antibody (NAb) activity against BetaCoV/Korea/KCDC03/2020 (NCCP43326, ancestral strain) and B.1.1.529 (NCCP43411, Omicron BA.1 variant) was measured using plaque reduction neutralization tests. A 50% neutralizing dilution (ND50) >10 was considered indicative of protective NAb titers. RESULTS: In total, 186 participants were enrolled between November 24, 2021, and June 30, 2022. The respective groups received the third dose at a median (interquartile range [IQR]) of 132 (125 - 191), 123 (122 - 126), 186 (166 - 193), and 182 (175 - 198) days after the second dose. Overall, ND50 was lower at V1 against Omicron BA.1 than against the ancestral strain. NAb titers against the ancestral strain and Omicron BA.1 variant at V2 were increased at least 30-fold (median [IQR], 1235.35 [1021.45 - 2374.65)] and 129.8 [65.3 - 250.7], respectively). ND50 titers against the ancestral strain and Omicron variant did not differ significantly among the four groups (P = 0.57). NAb titers were significantly lower against the Omicron variant than against the ancestral strain at V3 (median [IQR], 36.4 (17.55 - 75.09) vs. 325.9 [276.07 - 686.97]; P = 0.012). NAb titers against Omicron at V4 were 16 times lower than that at V3. Most sera exhibited a protective level (ND50 >10) at V4 (75.0% [24/32], 73.0% [27/37], 73.3% [22/30], and 70.6% [12/17] in the ChAd/ChAd/BNT, ChAd/ChAd/m1273, BNT/BNT/BNT, and BNT/BNT/m1273 groups, respectively), with no significant differences among groups (P = 0.99). CONCLUSION: A third COVID-19 mRNA vaccine dose restored waning NAb titers against Omicron BA.1. Our findings support a third-dose vaccination program to prevent the waning of humoral immunity to SARS-CoV-2.

No Association between SARS-CoV-2 Infection and the Polymorphism of the Toll-like Receptor 7 (TLR7) Gene in Female Population.

Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a single-stranded RNA virus. Toll-like receptor 7 (TLR7) recognizes single-stranded RNA viruses. The TLR7 gene plays a critical role in the human innate and adaptive immune response to SARS-CoV-2 infections. Genetic factors probably affect SARS-CoV-2 infection susceptibility. In the current study, our aim was to search for genetic variations associated with COVID-19 patients in the TLR7 gene of a Korean population. We designed five gene-specific primers to cover the coding region of the human TLR7 gene. Using amplicon sequencing, we screened the genetic polymorphisms in the coding region of the TLR7 gene in COVID-19 patients and healthy controls. The genotype frequencies, allele frequencies, and Hardy-Weinberg equilibrium (HWE) were examined. We identified a low-frequency synonymous single nucleotide polymorphism (SNP) (rs864058) in the coding region of the TLR7 gene. There were no significant differences in the genotype or allele frequencies of the TLR7 rs864058 polymorphism between COVID-19 female patients and healthy controls (p = 1.0). In conclusion, TLR7 (rs864058) polymorphism is low frequency in Korean populations and is not associated with SARS-CoV-2 infection.

Risk factors and clinical features for pulmonary paragonimiasis-associated pneumothorax.

BACKGROUND: Pulmonary paragonimiasis, a food-borne zoonotic helminthiasis, is a parasitic disease of the lung caused by infection with trematodes species of the genus Paragonimus. Although pneumothorax has been reported as occuring with paragonimiasis, to date no study has been performed concerning the clinical features and predictive risk factors for this condition. METHODS: This retrospective study, which aims to fill this gap, was conducted at Jeonbuk National University Hospital. All patients (aged ≥19 years) were diagnosed with paragonimiasis between May 2011 and December 2021. Medical records were reviewed and information concerning age, sex, vital signs, underlying diseases, clinical signs and symptoms, laboratory findings, radiologic findings, treatment, and clinical outcomes was collected. An odds ratio (OR) for the risk factors associated with pneumothorax was calculated using the binary logistic regression model. RESULTS: Among 179 consecutive patients diagnosed with pulmonary paragonimiasis, the postive rate of pneumothorax was 10.6% (19/179). Pneumothorax occurred mostly in the right lung (78.9%, 15/19), and intrapulmonary parenchymal lesions showed an ipsilateral relationship with pneumothorax (94.7%, 18/19). Fifteen patients (78.9%, 15/19) of pneumothorax associated with pulmonary paragonimiasis are accompanied by pleural effusion. Most of patients with pneumothorax (89.5%, 17/19) underwent chest tube insertion as a first treatment. Three patients (15.8%) showed relapses but in no case was a death recorded. Asthma (odds ratio [OR] 8.10, 95% confidence interval [CI] 1.43-45.91), chest pain (OR 8.15, 95% CI 2.70-24.58), and intrapulmonary lesions (OR 8.94, 95% CI 1.12-71.36) were independent risk factors for pulmonary paragonimiasis-associated pneumothorax. CONCLUSIONS: Our findings suggest that clinicians should keep in mind the possibility of pneumothorax when approached by patients with pulmonary paragonimiasis complaining of chest pain, accompanied by intrapulmonary lesions or with asthma as an underlying disease.

FDG PET/CT in Hantavirus Hemorrhagic Fever With Renal Syndrome.

ABSTRACT: A 58-year-old man with fever, myalgia, and dysuria was admitted to the hospital. Because of prolonged fever, FDG PET/CT was performed. Surprisingly, bilateral kidneys were rapidly enlarged for 5 days with the renal parenchyma showing intense hypermetabolism. FDG PET/CT demonstrated physiology of Hantavirus invading kidneys and causing nephritis. This case illustrates that FDG PET/CT could be the choice of image modality for diagnosis and treatment evaluation of patients suspected of hemorrhagic fever with renal syndrome. To the best of our knowledge, this is the first report of FDG PET/CT image for a patient with hemorrhagic fever with renal syndrome.

Temporal Dynamics of Serum Perforin and Granzyme during the Acute Phase of SARS-CoV-2 Infection.

BACKGROUND: As many SARS-CoV-2 infections are asymptomatic, it could be useful to be able to determine how much time has passed since infection. We explored the changes in the temporal levels of T cell-related proteins (including perforin and granzymes) in the sera of patients with SARS-CoV-2 infection using a commercially available assay. METHODS: This study enrolled 36 patients infected with SARS-CoV-2 and 20 healthy control participants. Blood samples were collected at three different times based on the number of days since symptom onset (early phase: 1-5 days, mid-phase: 6-10 days, late phase: 11-18 days). We assessed the temporal changes in the serum levels of perforin and granzymes in patients with SARS-CoV-2 infection by comparing the results with those obtained in the healthy control group. RESULTS: We identified a significantly low level of perforin in the early phase of SARS-CoV-2 infection (p < 0.01), which was restored to normal during the mid- and late phases of the infection. However, there was no difference in the temporal change in the level of granzymes in SARS-CoV-2-infected patients compared to the healthy control group. CONCLUSIONS: This finding suggests that SARS-CoV-2 infection paralyzed the perforin expression in the early period immediately after infection. Thus, serum perforin is a potential marker for identifying the acute phase of SARS-CoV-2 infection.

Temporal Dynamics of Serum Perforin and Granzymes in Three Different Clinical Stages of Virus-Induced Severe Fever with Thrombocytopenia Syndrome.

Virus-induced severe fever with thrombocytopenia syndrome (SFTS) induces a cell-mediated immune response that likely contributes to virus control in SFTS patients. To identify the temporal changes of the cell-mediated immune response, we investigated the changes in serum levels of perforin and granzymes at early periods after illness onset in SFTS patients. We analyzed 32 SFTS patients and compared the temporal patterns of serum perforin and granzyme A and B to that of 20 healthy control adults using the Mann-Whitney U test. Compared with healthy controls, the mean level of perforin was significantly reduced by 81% (P < 0.01) during the first week after illness onset, whereas granzyme B significantly increased by 4.6-fold (P = 0.02) in the first week after illness onset and decreased to normal afterward. During the study period, there was no significant difference in serum perforin and granzyme. These findings indicate that perforin and granzyme B in serum can be considered possible serologic markers that reflect the clinical stage of SFTS. Additional study is warranted for tracking circulating perforin and granzyme in different ages and for an extended period after illness onset.

Correction: Relative bradycardia in patients with COVID-19.

[This corrects the article DOI: 10.1186/s42444-022-00073-z.].

Maternal and Neonatal Outcomes in Pregnant Women With Coronavirus Disease 2019 in Korea.

BACKGROUND: This study aimed to describe the maternal, obstetrical, and neonatal outcomes in pregnant women with coronavirus disease 2019 (COVID-19) and identify the predictors associated with the severity of COVID-19. METHODS: This multicenter observational study included consecutive pregnant women admitted because of COVID-19 confirmed using reverse transcriptase-polymerase chain reaction (RT-PCR) test at 15 hospitals in the Republic of Korea between January 2020 and December 2021. RESULTS: A total of 257 women with COVID-19 and 62 newborns were included in this study. Most of the patients developed this disease during the third trimester. Nine patients (7.4%) developed pregnancy-related complications. All pregnant women received inpatient treatment, of whom 9 (3.5%) required intensive care, but none of them died. The gestational age at COVID-19 diagnosis (odds ratio [OR], 1.096, 95% confidence interval [CI], 1.04-1.15) and parity (OR, 1.703, 95% CI, 1.13-2.57) were identified as significant risk factors of severe diseases. Among women who delivered, 78.5% underwent cesarean section. Preterm birth (38.5%), premature rupture of membranes (7.7%), and miscarriage (4.6%) occurred, but there was no stillbirth or neonatal death. The RT-PCR test of newborns' amniotic fluid and umbilical cord blood samples was negative for severe acute respiratory syndrome coronavirus 2. CONCLUSION: At the time of COVID-19 diagnosis, gestational age and parity of pregnant women were the risk factors of disease severity. Vertical transmission of COVID-19 was not observed, and maternal severity did not significantly affect the neonatal prognosis.

Rapid and sensitive amplicon-based genome sequencing of SARS-CoV-2.

As SARS-CoV-2 variants of concern emerged, the genome sequencing of SARS-CoV-2 strains became more important. In this study, SARS-CoV-2 was sequenced using amplicon-based genome sequencing with MinION. The primer panel used in this study consisted of only 11 primer panels and the size of the amplicons was approximately 3 kb. Full genome sequences were obtained with a hundred copies of the SARS-CoV-2 genome, and 92.33% and 75.39% of the genome sequences were obtained with 10 copies of the SARS-CoV-2 genome. The few differences in nucleotide sequences originated from mutations in laboratory cultures and/or mixed nucleotide sequences. The quantification of the SARS-CoV-2 genomic RNA was done using RT-ddPCR methods, and the level of LoD indicated that this sequencing method can be used for any RT-qPCR positive clinical sample. The sequencing results of the SARS-CoV-2 variants and clinical samples showed that our methods were very reliable. The genome sequences of five individual clinical samples were almost identical, and the analysis of the sequence variance showed that most of these nucleotide substitutions were observed in the genome sequences of the other clinical samples, indicating this amplicon-based whole-genome sequencing method can be used in various clinical fields.

Three-dimensional network of nitrogen-doped carbon matrix-encapsulated Si nanoparticles/carbon nanofibers hybrids for lithium-ion battery anodes with excellent capability.

Three-dimensionally structured silicon (Si)-carbon (C) nanocomposites have great potential as anodes in lithium-ion batteries (LIBs). Here, we report a Nitrogen-doped graphene/carbon-encapsulated Si nanoparticle/carbon nanofiber composite (NG/C@Si/CNF) prepared by methods of surface modification, electrostatic self-assembly, cross-linking with heat treatment, and further carbonization as a potential high-performance anode for LIBs. The N-doped C matrix wrapped around Si nanoparticles improved the electrical conductivity of the composites and buffered the volume change of Si nanoparticles during lithiation/delithiation. Uniformly dispersed CNF in composites acted as conductive networks for the fast transport of ions and electrons. The entire tightly connected organic material of NG/C@Si and CNF prevented the crushing and shedding of particles and maintained the integrity of the electrode structure. The NG/C@Si/CNF composite exhibited better rate capability and cycling performance compared with the other electrode materials. After 100 cycles, the electrode maintained a high reversible specific capacity of 1371.4 mAh/g.

Serum proteomics of severe fever with thrombocytopenia syndrome patients.

BACKGROUND: Dabie bandavirus, also termed as severe fever with thrombocytopenia syndrome virus (SFTSV), was first isolated in China in 2010. At this time, the virus was found to have spread to South Korea, Japan, and other countries. A high case fatality rate is reported for SFTS, ranging from 12-50% within various sources. Several omics for clinical studies among SFTS patients as well as studies of cultured SFTSV have attempted to characterize the relevant molecular biology and epidemiology of the disease. However, a global serum proteomics analysis among SFTS patients has not yet been reported to date. METHODS: In the current study, we evaluated comparative serum proteomics among SFTS patients (eight recovered patients and three deceased patients) with the goal of identifying the protein expression patterns associated with the clinical manifestations of SFTS. RESULTS: The proteomic results in the current study showed that the coagulation factor proteins, protein S and protein C, were statistically significantly downregulated among the deceased patients. Downregulation of the complement system as well as prolonged neutrophil activation were also observed. Additionally, the downstream proteins of tumour necrosis factor alpha, neutrophil-activating cytokine, and interleukin-1ß, an inflammatory cytokine, were overexpressed. CONCLUSIONS: Thrombocytopenia and multiple organ failure are the major immediate causes of death among SFTS patients. In this study, serum proteomic changes related to thrombocytopenia, abnormal immune response, and inflammatory activation were documented in SFTS patients. These findings provide useful information for understanding the clinical manifestations of SFTS.

New Genotypes and Diversity of Orientia tsutsugamushi DNA samples from Patients with Scrub Typhus in South Korea as Determined by Multilocus Sequence Typing.

Orientia tsutsugamushi, an obligate intracellular organism, is the causative agent of scrub typhus. Multilocus sequence typing (MLST) is a genetic typing method that provides a unified bacterial isolate characterization approach. However, there are no comparative studies in South Korea on the genotypic properties of O. tsutsugamushi based on MLST. To conduct a comparative analysis with previous data collected from Thailand, Laos, and Japan, we investigated the genetic diversity of O. tsutsugamushi from 51 patients with scrub typhus in South Korea by using MLST. The MLST analysis revealed 10 new alleles in the housekeeping genes: gpsA, n = 2; mdh, n = 1; nrdB, n = 1; nuoF, n = 1; ppdK, n = 1; sucB, n = 2; and sucD, n = 2. These novel alleles led to the assignment of six new sequence types (STs) (ST93-98). The 51 samples corresponded to seven different STs (ST48 and ST93-98), with ST48 accounting for the largest proportion (49.0%) of O. tsutsugamushi STs in South Korea. Interestingly, O. tsutsugamushi from patients with scrub typhus in South Korea were clustered in two different clades, and the five Korean STs (ST48, ST93, ST94, ST95, and ST98) were close genetically to ST80, which was isolated from Laos. The remaining two STs (ST96 and ST97) were close genetically to ST49 (Ikeda, Japan). Overall, our results suggest that the relative genetic stability and the clonal populations of O. tsutsugamushi strains in South Korea have remained mostly conserved.

Decreased door-to-balloon time in patients with ST-segment elevation myocardial infarction during the early COVID-19 pandemic in South Korea: An observational study.

The coronavirus disease 2019 (COVID-19) resulted in a marked decrease in the number of patient visits for acute myocardial infarction and delayed patient response and intervention in several countries. This study evaluated the effect of the COVID-19 pandemic on the number of patients, patient response time (pain-to-door), and intervention time (door-to-balloon) for patients with ST-segment elevation myocardial infarction (STEMI) and non-ST-segment elevation myocardial infarction (NSTEMI). Patients with STEMI or NSTEMI visiting a hospital in South Korea who underwent primary coronary intervention during the COVID-19 pandemic (January 29, 2020, to December 31, 2020) were compared with those in the equivalent period from 2018 to 2019. Patient response and intervention times were compared for the COVID-19 pandemic window (2020) and the equivalent period from 2018 to 2019. We observed no decrease in the number of patients with STEMI (P = .88) and NSTEMI (P = 1.00) during the COVID-19 pandemic compared to that in the previous years. Patient response times (STEMI: P = .39; NSTEMI: P = .59) during the overall COVID-19 pandemic period did not differ significantly. However, we identified a significant decrease in door-to-balloon time among patients with STEMI (14%; P < .01) during the early COVID-19 pandemic. We found that the number of patients with STEMI and NSTEMI was consistent during the COVID-19 pandemic and that no time delays in patient response and intervention occurred. However, the door-to-balloon time among patients with STEMI significantly reduced during the early COVID-19 pandemic, which could be attributed to decreased emergency care utilization during the early pandemic.

Proteomics-based diagnostic peptide discovery for severe fever with thrombocytopenia syndrome virus in patients.

BACKGROUND: Severe fever with thrombocytopenia syndrome (SFTS) virus is an emerging infectious virus which causes severe hemorrhage, thrombocytopenia, and leukopenia, with a high fatality rate. Since there is no approved therapeutics or vaccines for SFTS, early diagnosis is essential to manage this infectious disease. METHODS: Here, we tried to detect SFTS virus in serum samples from SFTS patients by proteomic analysis. Firstly, in order to obtain the reference MS/MS spectral data of SFTS virus, medium from infected Vero cell culture was used for shotgun proteomic analysis. Then, tryptic peptides in sera from SFTS patients were confirmed by comparative analysis with the reference MS/MS spectral data of SFTS virus. RESULTS: Proteomic analysis of culture medium successfully discovered tryptic peptides from all the five antigen proteins of SFTS virus. The comparative spectral analysis of sera of SFTS patients revealed that the N-terminal tryptic peptide of the nucleocapsid (N) protein is the major epitope of SFTS virus detected in the patient samples. The prevalence of the peptides was strongly correlated with the viral load in the clinical samples. CONCLUSIONS: Proteomic analysis of SFTS patient samples revealed that nucleocapsid (N) protein is the major antigen proteins in sera of SFTS patients and N-terminal tryptic peptide of the N protein might be a useful proteomic target for direct detection of SFTS virus. These findings suggest that proteomic analysis could be an alternative tool for detection of pathogens in clinical samples and diagnosis of infectious diseases.

ZnO Nanowire-Based Early Detection of SARS-CoV-2 Antibody Responses in Asymptomatic Patients with COVID-19.

A serological immunoassay based on enzyme-linked immunosorbent assay (ELISA) is a crucial tool for screening and identification of human SARS-CoV-2 seroconversion. Various immunoassays are developed to detect the spike 1 (S1) and nucleocapsid (NP) proteins of SARS-CoV-2; however, these serological tests have low sensitivity. Here, a novel microplate (MP) is developed on which a ZnO nanowire (NW) is fabricated by a modified hydrothermal synthesis method. This plate is coated with SARS-CoV-2 NP and used as a fluorescent immunoassay (FIA) to detect antibodies specific for SARS-CoV-2 NP. Compared with the bare MP, the ZnO-NW MP binds high levels (up to 5 µg mL-1) of SARS-CoV-2 NP tagged to histidine without any surface treatment. A novel serological assay based on the ZnO-NW MP is more sensitive than a commercial immunoassay, enabling early detection (within <5 days of a reverse transcription polymerase chain reaction-confirmed COVID-19 infection) of anti-SARS-CoV-2 NP IgG antibodies in asymptomatic patients with COVID-19. This is the first assay to detect early antibody responses to SARS-CoV-2 in asymptomatic patients. Therefore, this serological assay will facilitate accurate diagnosis of COVID-19, as well as estimation of COVID-19 prevalence and incidence.