OBJECTIVES: To investigate the clinical characteristics of neonates infected with the Omicron variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). METHODS: A cross-sectional survey was conducted on 542 hospitalized neonates with confirmed coronavirus disease 2019 (COVID-19) in 27 hospitals in Shenzhen from December 7, 2022, to January 12, 2023 (during the Omicron variant epidemic period). The neonates were divided into two groups: asymptomatic infection and symptomatic infection. The clinical characteristics, results of laboratory examination, chest X-ray findings, and outcome were compared between the two groups. RESULTS: Among the 542 neonates, there were 285 males and 257 females. Among them, 515 (95.0%) were full-term infants, and 27 (5.0%) were preterm infants. The asymptomatic infection group had 60 cases, and the symptomatic infection group had 482 cases. Among them, 336 cases (69.7%) were mild, 125 cases (25.9%) were moderate, 15 cases (3.1%) were severe, and 6 cases (1.2%) were critical. Fever was the most common symptom (434 cases, 90.0%), followed by cough and/or spitting (183 cases, 38.0%), nasal congestion and/or runny nose (131 cases, 27.2%), shortness of breath (36 cases, 7.5%), and feeding intolerance (30 cases, 6.2%). Among the 325 cases who underwent chest X-ray examination, 136 cases (41.8%) had patchy or consolidative shadows in the lungs, 2 cases (0.6%) had pneumothorax, 2 cases (0.6%) had decreased lung transparency, and 185 cases (57.0%) showed no abnormality. Among the 396 cases (73.1%) who received treatment, 341 cases (86.1%) received symptomatic treatment, 137 cases (34.6%) received antibiotic treatment, 4 cases (1.0%) received immunoglobulin treatment, and 23 cases (5.8%) received respiratory support treatment. All 542 neonates were discharged from the hospital after their clinical symptoms were relieved, and the median hospital stay was 5 days. The white blood cell count, neutrophil count, hemoglobin, and procalcitonin were lower in the symptomatic infection group than those in the asymptomatic infection group (P<0.05), while the platelet count and blood glucose levels were higher in the symptomatic infection group than those in the asymptomatic infection group (P<0.05). The proportions of neonates with decreased neutrophil count, increased platelet count, and decreased hemoglobin concentration were higher in the symptomatic infection group than those in the asymptomatic group (P<0.05). CONCLUSIONS Most neonates with COVID-19 caused by the Omicron variant of SARS-CoV-2 are mild, with fever as the predominant symptom. Symptomatic neonates with COVID-19 are often accompanied by decreased neutrophil count, increased platelet count, and decreased hemoglobin level. Symptomatic treatment is the main treatment, and the prognosis is good.
Male ; Infant ; Female ; Humans ; Infant, Newborn ; SARS-CoV-2 ; COVID-19/therapy* ; Cross-Sectional Studies ; Asymptomatic Infections/epidemiology* ; Infant, Premature ; Fever

OBJECTIVES: With the continuous generation of new variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the pressure of epidemic prevention and control continues to increase in China. Omicron with stronger infectiousness, immune escape ability and repeated infection ability spread to many countries and regions around the world in a short period of time. China has also successively reported cases of imported Omicron infections. This study aims to understand the epidemiological characteristics of Omicron variant via analyzing the epidemiological characteristics of imported patients with Omicron in Hunan Province, and to provide reference for preventing and controlling the imported epidemics. METHODS: The clinical data of imported patients with coronavirus disease 2019 admitted to Hunan Province from December 16 to December 31, 2021 were retrospectively collected. The epidemiological information, general information, clinical classification, clinical symptoms, vaccination status, and lung CT were analyzed. Nasopharyngeal swabs and blood samples were collected. Virus nucleic acid was detected by magnetic beads method using SARS-CoV-2 detection kit. Ct values of ORF1ab gene and N gene were compared between asymptomatic infected patients and confirmed patients. The specific IgM and IgG antibodies were detected by chemiluminescence assay using SARS-CoV-2 IgM test kit and SARS-CoV-2 IgG test kit, respectively. Ct values of IgM and IgG antibodies were compared between asymptomatic infected patients and confirmed patients. RESULTS: Seventeen patients with Omicron variant infection were treated in Hunan, including 15 confirmed patients (5 common type and 10 mild type) and 2 asymptomatic infection patients. The 17 patients were all Chinese, they were generally young, and 16 were male. There were 9 patients with diseases. Of them 3 patients had respiratory diseases. All 17 patients had completed the whole process of vaccination, but only one person received a booster shot of SARS-CoV-2 vaccine. The clinical manifestations of the patients were mild, mainly including dry/painful/itchy throat, cough, and fatigue. The total protein and creatine in the asymptomatic infection and confirmed cases infected with Omicron variant were all within the normal range, but other biochemical indicators were abnormal. There were the significant differences in C-reactive protein and fibrinogen between asymptomatic infection and confirmed patients (both P<0.05). There were more patients with elevated C-reactive protein in confirmed patients than without confirmed ones. The detection rate of specific IgM and IgG antibodies on admission was 100%, and there was no significant difference in the specific antibody levels between asymptomatic infection and confirmed patients (P>0.05). There were no significant differences in Ct values of ORF1ab gene and N gene (21.35 and 18.39 vs 19.22 and 15.67) between the asymptomatic infection and the confirmed patients (both P>0.05). Only 3 patients had abnormal lung CT, showing a small amount of patchy and cord-like shadows. One of them had no abnormality on admission but had pulmonary lesions and migratory phenomenon after admission. CONCLUSIONS The patients with Omicron variant tend to be young people and have milder clinical symptoms, but the viral load is high and the infectiveness is strong. Therefore, the timely identification and effective isolation and control for asymptomatic infections and confirmed patients with mild symptoms are extremely important. In terms of epidemic prevention and control, the government still needs to strengthen the risk control of overseas input, adhere to normalized epidemic prevention and control measures, to effectively control the source of infection, cut off the route of transmission, and protect vulnerable people.
Asymptomatic Infections ; C-Reactive Protein ; COVID-19/virology* ; COVID-19 Vaccines ; China/epidemiology* ; Female ; Humans ; Immunoglobulin G ; Immunoglobulin M ; Male ; Retrospective Studies ; SARS-CoV-2

Objective: To analyze the time distribution of the first positive nucleic acid detection in imported cases infected with SARS-CoV-2 reported nationwide in China and provide references for further improvement of the prevention and control of COVID-19 in international travelers. Methods: The data of imported cases infected with SARS-CoV-2 reported by provinces from 24 July 2020 and 23 July 2021 were collected for the analysis on the time distribution of the first positive nucleic acid detection after entering China. Results: A total of 7 199 imported cases infected with SARS-CoV-2 were reported in 28 provinces during 24 July 2020 to 23 July 2021. The median interval (Q₁, Q₃) from the entry to the first positive nucleic acid detection of SARS-CoV-2 was 1 (0, 5) day. The imported cases who had the first positive nucleic acid detections within 14 days and 14 days later after the entry accounted for 95.15% (6 850/7 199) and 4.85% (349/7 199) respectively. Among these cases, 3.65% (263/7 199), 0.88% (63/7 199) and 0.32% (23/7 199) had the first positive nucleic acid detections within 15-21 days, 22-28 days and 28 days later after the entry respectively. The proportion of asymptomatic infections were 47.24% (3 236/6 850) and 63.61% (222/349) among the cases who had the first positive nucleic acid detections within 14 days and 14 days later after the entry respectively. A total of 39.54% (138/349) of cases infected with SARS-CoV-2 with the first positive nucleic acid detections 14 days later after the entry had inter-provincial travel after the discharge of entry point isolation. Conclusions: About 5% of the imported cases infected with SARS-CoV-2 were first positive 14 days later after the entry. In order to effectively reduce the risk of domestic COVID-19 secondary outbreaks caused by imported cases, it is suggested to add a nucleic acid test on 8^th -13^th day after the entry.
Asymptomatic Infections ; COVID-19 ; China/epidemiology* ; Humans ; Nucleic Acids ; SARS-CoV-2

Through literature review and group discussion, Special Expert Group for Control of the Epidemic of Novel Coronavirus Pneumonia of the Chinese Preventive Medicine Association formulated an update on the epidemiological characteristics of novel coronavirus pneumonia (NCP). The initial source of the 2019 novel coronavirus (2019-nCoV) was the Huanan seafood market in Wuhan, Hubei province, China, with pangolins as a potential animal host. Currently the main source of infection is NCP patients, and asymptomatic carriers may also be infectious. The virus is believed transmitted mostly via droplets or contact. People are all generally susceptible to the virus. The average incubation period was 5.2 days, and the basic reproductive number R(0) was 2.2 at the onset of the outbreak. Most NCP patients were clinically mild cases. The case fatality rate was 2.38%, and elderly men with underlying diseases were at a higher risk of death. Strategies for prevention and control of NCP include improving epidemic surveillance, quarantining the source of infection, speeding up the diagnosis of suspected cases, optimizing the management of close contacts, tightening prevention and control of cluster outbreaks and hospital infection, preventing possible rebound of the epidemic after people return to work from the Chinese Spring Festival holiday, and strengthening community prevention and control.
Aged ; Animals ; Asymptomatic Diseases/epidemiology* ; Betacoronavirus ; COVID-19 ; China/epidemiology* ; Contact Tracing ; Coronavirus ; Coronavirus Infections/epidemiology* ; Humans ; Infectious Disease Incubation Period ; Male ; Pandemics ; Pneumonia, Viral/epidemiology* ; Public Health Surveillance/methods* ; Quarantine ; SARS-CoV-2

Objective: An outbreak of 2019 novel coronavirus diseases (COVID-19) in Wuhan, China has spread quickly nationwide. Here, we report results of a descriptive, exploratory analysis of all cases diagnosed as of February 11, 2020. Methods: All COVID-19 cases reported through February 11, 2020 were extracted from China's Infectious Disease Information System. Analyses included: 1) summary of patient characteristics; 2) examination of age distributions and sex ratios; 3) calculation of case fatality and mortality rates; 4) geo-temporal analysis of viral spread; 5) epidemiological curve construction; and 6) subgroup analysis. Results: A total of 72 314 patient records-44 672 (61.8%) confirmed cases, 16 186 (22.4%) suspected cases, 10567 (14.6%) clinical diagnosed cases (Hubei only), and 889 asymptomatic cases (1.2%)-contributed data for the analysis. Among confirmed cases, most were aged 30-79 years (86.6%), diagnosed in Hubei (74.7%), and considered mild/mild pneumonia (80.9%). A total of 1 023 deaths occurred among confirmed cases for an overall case-fatality rate of 2.3%. The COVID-19 spread outward from Hubei sometime after December 2019 and by February 11, 2020, 1 386 counties across all 31 provinces were affected. The epidemic curve of onset of symptoms peaked in January 23-26, then began to decline leading up to February 11. A total of 1 716 health workers have become infected and 5 have died (0.3%). Conclusions: The COVID-19 epidemic has spread very quickly. It only took 30 days to expand from Hubei to the rest of Mainland China. With many people returning from a long holiday, China needs to prepare for the possible rebound of the epidemic.
Adult ; Aged ; Asymptomatic Diseases/epidemiology* ; Betacoronavirus ; COVID-19 ; China/epidemiology* ; Coronavirus ; Coronavirus Infections/mortality* ; Disease Outbreaks ; Humans ; Middle Aged ; Mortality/trends* ; Pandemics ; Pneumonia, Viral/mortality* ; SARS-CoV-2

Plasmodium vivax is more challenging to control and eliminate than P. falciparum due to its more asymptomatic infections with low parasite densities making diagnosis more difficult, in addition to its unique biological characteristics. The potential re-introduction of incidence cases, either through borders or via human migrations, is another major hurdle to sustained control and elimination. The Republic of Korea has experienced re-emergence of vivax malaria in 1993 but is one of the 32 malaria-eliminating countries to-date. Despite achieving successful nationwide control and elimination of vivax malaria, the evolutionary characteristics of vivax malaria isolates in the Republic of Korea have not been fully understood. In this review, we present an overview of the genetic variability of such isolates to increase understanding of the epidemiology, diversity, and dynamics of vivax populations in the Republic of Korea.
Asymptomatic Infections ; Diagnosis ; Epidemiology ; Genetic Variation ; Human Migration ; Incidence ; Korea ; Malaria ; Malaria, Vivax ; Parasites ; Plasmodium vivax ; Plasmodium ; Population Characteristics ; Republic of Korea

OBJECTIVES: The rates of asymptomatic infection with Middle East Respiratory Syndrome (MERS) coronavirus vary. A serologic study was conducted to determine the asymptomatic MERS infection rate in healthcare workers and non-healthcare workers by exposure status.METHODS: Study participants were selected from contacts of MERS patients based on a priority system in 4 regions strongly affected by the 2015 MERS outbreak. A sero-epidemiological survey was performed in 1,610 contacts (average duration from exposure to test, 4.8 months), and the collected sera were tested using an enzyme-linked immunespecific assay (ELISA), immunofluorescence assay (IFA), and plaque reduction neutralization antibody test (PRNT). Among the 1,610 contacts, there were 7 ELISA-positive cases, of which 1 exhibited positive IFA and PRNT results.RESULTS: The asymptomatic infection rate was 0.060% (95% confidence interval, 0.002 to 0.346). The asymptomatic MERS case was a patient who had been hospitalized with patient zero on the same floor of the hospital at the same time. The case was quarantined at home for 2 weeks after discharge, and had underlying diseases, including hypertension, angina, and degenerative arthritis.CONCLUSIONS: The asymptomatic infection was acquired via healthcare-associated transmission. Thus, it is necessary to extend serologic studies to include inpatient contacts who have no symptoms.
Asymptomatic Infections ; Coronavirus ; Coronavirus Infections ; Cross Infection ; Delivery of Health Care ; Epidemiology ; Fluorescent Antibody Technique ; Humans ; Hypertension ; Inpatients ; Korea ; Middle East Respiratory Syndrome Coronavirus ; Middle East ; Osteoarthritis

OBJECTIVES: The rates of asymptomatic infection with Middle East Respiratory Syndrome (MERS) coronavirus vary. A serologic study was conducted to determine the asymptomatic MERS infection rate in healthcare workers and non-healthcare workers by exposure status. METHODS: Study participants were selected from contacts of MERS patients based on a priority system in 4 regions strongly affected by the 2015 MERS outbreak. A sero-epidemiological survey was performed in 1,610 contacts (average duration from exposure to test, 4.8 months), and the collected sera were tested using an enzyme-linked immunespecific assay (ELISA), immunofluorescence assay (IFA), and plaque reduction neutralization antibody test (PRNT). Among the 1,610 contacts, there were 7 ELISA-positive cases, of which 1 exhibited positive IFA and PRNT results. RESULTS: The asymptomatic infection rate was 0.060% (95% confidence interval, 0.002 to 0.346). The asymptomatic MERS case was a patient who had been hospitalized with patient zero on the same floor of the hospital at the same time. The case was quarantined at home for 2 weeks after discharge, and had underlying diseases, including hypertension, angina, and degenerative arthritis. CONCLUSIONS: The asymptomatic infection was acquired via healthcare-associated transmission. Thus, it is necessary to extend serologic studies to include inpatient contacts who have no symptoms.
Asymptomatic Infections ; Coronavirus ; Coronavirus Infections* ; Cross Infection ; Delivery of Health Care ; Epidemiology ; Fluorescent Antibody Technique ; Humans ; Hypertension ; Inpatients ; Korea* ; Middle East Respiratory Syndrome Coronavirus* ; Middle East* ; Osteoarthritis

PURPOSE: Enterovirus (EV) infection in children can manifest various diseases from asymptomatic infection to nonspecific febrile illness, hand-foot-mouth disease, and aseptic meningitis. This study was aimed to investigate epidemiology and clinical significance of various genotypes of EV infections in pediatric inpatient. METHODS: We collected the stool samples from the admitted pediatric patients in Inha University Hospital from March 2014 to March 2015. EV detection and genotype identification were performed by real-time RT-PCR and semi-nested RT-PCR. Phylogenetic trees were constructed by neighbor joining method. RESULTS: A total of 400 samples were collected during study period and 112 patients (28%) were diagnosed with EV infections. The mean age of EV positive patients was 2.66 years (0.1-14) and sex ratio was 1.73:1. Genetic sequences of EVs were identified; coxsackievirus B5 (17, 15.2%), coxsackievirus A16 (13, 11.6%), enterovirus 71 (10, 8.9%), and coxsackievirus A2 (9, 8.0%). Nonspecific febrile illness (96, 86%) was the most common clinical manifestation and the duration of fever was 0-11 days (mean 3.1 days). Rash (44, 39%) and meningitis (43, 38%) were followed. Patients who were attending daycare center or had siblings accounted for 82.1%. Phylogenetic relationship tree revealed 6 distinct genogroups among 56 types of EVs. CONCLUSIONS: This study is the report of epidemiology, serotype distribution and clinical manifestations of children with EV infection in Incheon. This data will be helpful for further study about the epidemiology of EV infection in Korea.
Asymptomatic Infections ; Child ; Enterovirus* ; Epidemiology* ; Exanthema ; Fever ; Genotype ; Humans ; Incheon* ; Inpatients* ; Korea ; Meningitis ; Meningitis, Aseptic ; Sex Ratio ; Siblings ; Trees

PURPOSE: Human metapneumovirus(hMPV) is a respiratory viral pathogen that causes a wide spectrum of illnesses, ranging from asymptomatic infection to severe bronchiolitis. The virus has been identified world widely, but so far it has not been published in Korea. METHODS: We obtained clinical samples by nasopharyngeal aspiration from 218 children hospitalized due to acute lower respiratory tract infections at Soonchunhyang University Hospital in Cheonan from October, 2004 to April, 2005. We designed specific primers from conserved region of fusion glycoprotein of hMPV. Total RNA was extracted and RT-PCR was performed, and single specific 423 bp product was obtained. The PCR product was confirmed to be fusion glycoprotein RNA by sequencing. RESULTS: We detected hMPV in 15(6.9 percent) of the 218 hospitalized children. The infected children comprised nine boys and six girls; their mean age was 2.8 years(5 mo-12 yrs) and they were diagnosed with pneumonia(60 percent), bronchiolitis(33.3 percent), croup(6.6 percent). The number of cases of detected hMPV in Korea increased dramatically during the period from March to May 2005. CONCLUSION: hMPV is circulating in Korean children and is associated with respiratory tract infection. Additional studies are required to define the epidemiology and the extent of diseases in the general population caused by hMPV.
Asymptomatic Infections ; Bronchiolitis ; Child* ; Child, Hospitalized ; Chungcheongnam-do ; Epidemiology ; Female ; Glycoproteins ; Humans* ; Korea ; Metapneumovirus* ; Polymerase Chain Reaction ; Respiratory Tract Infections ; RNA