Changes in Spectrum of Respiratory Pathogen Infections and Disease Severity Among Children in Hohhot: Impact of COVID-19 Prevention Measures (preprint)

Background Acute respiratory infections (ARIs) are caused by various pathogens, and the outbreak of the novel coronavirus has led to changes in the patterns of respiratory pathogen infections. Through long-term study of respiratory tract infection data in children from Hohhot, significant differences in the spectrum of respiratory pathogen infections, disease severity, and seasonal patterns have been discovered between 2022 and 2023.Methods Throat swabs were collected from 605 children with ARIs at the First Hospital of Hohhot, and pathogen detection was performed using microarray technology. Blood biomarkers, symptoms, and clinical diagnoses were evaluated.Results The study found that 56.03% of the patients were male, with an average age of 3.45 years. Pathogen dynamics revealed that SARS-CoV-2 was the most prevalent infection, accounting for 262 cases. It persisted from October 2022 to January 2023 and then disappeared. Influenza A virus (IAV) cases peaked in March 2023. Respiratory syncytial virus (RSV), Influenza B virus (IBV), Parainfluenza virus (PIV), Mycoplasma pneumoniae (M. pneumoniae), Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), and Group A streptococcus (GAS) were not detected after December 2022. The proportion of mixed infections was 41.94% among SARS-CoV-2 patients, while other pathogens had mixed infection rates exceeding 57.14%. Before December 2022, the mean value of white blood cell (WBC) count for Streptococcus pneumoniae (S. pneumoniae), Haemophilus influenzae (H. influenzae), Epstein-Barr virus (EBV), and Cytomegalovirus (CMV) was 8.83*10^9/L, C-reactive protein (CRP) was 18.36 mg/L, and procalcitonin (PCT) was 1.11 ng /ml. After December 2022, these values decreased to 5.5*10^9/L, 6.33 mg/L, and 0.24 ng /ml, respectively. Similarly, the proportion of patients with cough, difficulty breathing, and running nose, as well as the diagnosis of lower respiratory tract infections, decreased in December 2022. However, the situation was different for SARS-CoV-2 infections.Conclusions Strict SARS-CoV-2 policies reduced the infection risk for S. pneumoniae, H. influenzae, EBV, and other pathogens before November 2022. However, patient symptoms worsened compared to after November 2022, possibly due to an excessive focus on SARS-CoV-2, neglecting other diseases, and reduced population immunity to respiratory infections.

Decreased Hospital-Acquired Respiratory Infections among elder Inpatients in General Hospital during the COVID-19 Pandemic (preprint)

Background In order to avoid nosocomial transmission of COVID-19, various prevention and control measures have been strictly implemented in medical institutions. These strict measures can probably reduce the incidence of hospital acquired respiratory infections. We conducted this study to assess changes in the prevalence of hospital acquired respiratory infections during a period of national attention to the prevention the COVID-19 pandemic.Methods We retrospectively analyzed the clinical data of patients from October to December 2019 and from October to December 2020. The diagnostic of hospital acquired respiratory infections was based on CDC/NHSN criteria. We compared the incidence and mortality rate of hospital acquired respiratory infections between these 2 periods. We also used multivariate logistics regression analysis for risk factors associated with mortality.Results In 2020, a total of 2921 patients’ data were surveyed, as compared with 2211 patients in 2019. Incidence of hospital acquired respiratory infections was lower in 2020 (2.9% vs. 4.7%, P = 0.001). In hospital mortality of patients with hospital acquired respiratory infections had no significant difference (38.4% vs. 30.5%, p = 0.252). Multivariate logistics regression analysis showed that severe pneumonia (RR = 28.235, 95%CI: 10.122, 78.759, p = 0.000), previous malignant tumor (RR = 4.599, 95%CI: 1.768, 11.963, p = 0.002) and cardiac injury (RR = 2.264, 95%CI: 0.935, 5.485, p = 0.07) were associated with an increased risk of mortality.Conclusions The incidence of hospital acquired respiratory tract infections was significantly decreased during COVID-19 period as a result of the adoption of infection prevention and control measures in medical institutions. Elder patients with severe pneumonia and previous malignant tumor were at high risk for death in hospital.

Photoacoustic detection of SARS-CoV-2 spike N501Y single-nucleotide polymorphism based on branched rolling circle amplification

Rapid and accurate diagnosis of SARS-CoV-2 single-nucleotide variations is an urgent need for the initial detection of local circulation and monitoring the alternation of dominant variant. In this proof-of-concept study, a homogeneous and isothermal photoacoustic biosensor is demonstrated for rapid molecular amplification and detection of a synthetic DNA corresponding to SARS-CoV-2 spike N501Y. Branched rolling circle amplification produces single-stranded amplicons that can aggregate detection probe-modified AuNPs, which induces a strong photoacoustic signal at 640 nm due to both the surface plasmon resonance shift and the size-dependent effect of laser-induced nanobubbles, achieving a sub-femtomolar detection limit within a total assay time of 80 min. The limit of detection can be kept when measuring 5% serum samples. Moreover, the proposed biosensor is highly specific for single-nucleotide polymorphism discrimination and robust against background DNA.

Air Quality Changes during the COVID-19 Lockdown in an Industrial City in North China: Post-Pandemic Proposals for Air Quality Improvement

To better understand the changes in air pollutants in an industrial city, Handan, North China, during the COVID-19 lockdown period, the air quality and meteorological conditions were recorded from 1 January to 3 March 2020 and the corresponding period in 2019. Compared to the corresponding period in 2019, the largest reduction in PM2.5–10, PM2.5, NO2 and CO occurred during the COVID-19 lockdown period. PM2.5–10 displayed the highest reduction (66.6%), followed by NO2 (58.4%) and PM2.5 (50.1%), while O3 increased by 13.9%. Similarly, compared with the pre-COVID-19 period, NO2 significantly decreased by 66.1% during the COVID-19 lockdown, followed by PM2.5–10 (45.9%) and PM2.5 (42.4%), while O3 increased significantly (126%). Among the different functional areas, PM2.5 and PM2.5–10 dropped the most in the commercial area during the COVID-19 lockdown. NO2 and SO2 decreased the most in the traffic and residential areas, respectively, while NO2 increased only in the township and SO2 increased the most in the industrial area. O3 increased in all functional areas to different extents. Potential source contribution function analysis indicated that not only the local air pollution lessened, but also long-distance or inter-regional transport contributed much less to heavy pollution during the lockdown period. These results indicate that the COVID-19 lockdown measures led to significantly reduced PM and NO2 but increased O3, highlighting the importance of the synergetic control of PM2.5 and O3, as well as regional joint prevention and the control of air pollution. Moreover, it is necessary to formulate air pollution control measures according to functional areas on a city scale.

Phenotypes and Functions of Dendritic Cells in SARS-CoV-2 Vaccine-derived Humoral Immunity (preprint)

DCs regulate humoral immunity against SARS-CoV-2 by regulating CD4 + T cell activation, but the relations between DC phenotypes and functions and anti-RBD antibodies are unclear. We conducted this observational study in Huashan Hospital using a third 6.5U BBIBP-CorV or 25 µg ZF2001 administered at an interval of 4 to 8 months following the previous two doses in healthy adults. anti-RBD response and neutralizing titers against SARS-CoV-2 and VOCs were examined. DC maturation markers and pattern recognition receptors and cytokines produced by DC were measured, and DC function was tested in mixed lymphocyte reaction(MLR). Mean anti-RBD Ab and IgG rose from 22.08 and 9.17 on D0 to 4704.18 and 798.11 on D14(BAU/ml). Meanwhile, the surrogate virus neutralization test(sVNT) elevated from 17.15 on D0 to 2538.83 on D14. The expression of DC maturation markers on D3 and MLR were negatively correlated to sVNT, anti-RBD antibody, and IgG titers on D14(Spearman r=-0.558~-0.326) and D28(Spearman r=-0.615~-0.397), but positively correlated to IgG/Ab ratio(Spearman r = 0.249 ~ 0.509). DC function in activating T cells was also negatively related to anti-RBD antibody titer on D28(r=-0.532~-0.453, p = 0.015 ~ 0.035), and positively correlated with the proportion of anti-RBD IgG in Ab(r = 0.490 ~ 0.561, p = 0.010 ~ 0.032). DC-SIGN level showed a relation to antibody titer and IgG proportion opposite to DC maturation and function and was negatively related to the level of IL-10 produced by DCs. Our research suggested that DCs controlled CD4 + T cells in differentiating into regular T cells, and DC-SIGN might restrain T regular cells by suppressing IL-10 production of DC in anti-SARS-CoV-2 vaccination.

Amphiphilic Janus Microspheres Prepared by Caged Photoactivatable Alkoxysilane

A simple photolysis route was proposed to prepare Amphiphilic Janus Particles (AJP) based on SiO2 microspheres. The surface of SiO2 microspheres were modified by photoactive alkoxysilane, which was synthesized by dealcoholization condensation of 6-nitroveratroyloxycarbonyl and isocyanatopropyl-triethoxysilane. UV irradiation caused eater-breaking allowed for the precise control of hydrophilic modification of the hemispherical exposed particles surfaces. The component and morphology of the obtained particles were characterized by fourier transform infrared spectroscopy and ultraviolet-visible spectroscopy, and the Janus feature was evaluated by scanning electron microscopy, transmission electron microscopy, and dispersity in the oil–water dual-phases. The following results were obtained. The AJP with 450 nm size processes the hydrophilic amino groups on one side and the hydrophobic 6-nitroveratryloxycarbonyl moieties on the other. Additionally, the AJP were located at the phase boundary between water and n-hexane, and the negative charged gold nanoparticles with 25 nm size were adsorbed only onto the side with the positive charged amino groups. The AJP have interfacial adsorption energies that can be as much as three times larger than that of homogeneous particles and thus exhibit excellent surface activities.

Omicron: a chimera of two early SARS-CoV-2 lineages (preprint)

The current global epidemiology of COVID-19 is now characterized by the emergence and rapid spread of the SARS-CoV-2 Omicron variant on a global scale 1,2 . Despite the variant’s prompt predominance, there remain knowledge gaps in its origin and evolution history 3–6 . Here, we show that Omicron lineage SARS-CoV-2 is characterized by the feature of chimera. It was generated by genomic recombination of two early PANGO lineages of SARS-CoV-2. In the recombination event, strains with medium or high circulating intensity like SARS-CoV-2/human/USA/COR-21-434196/2021 belonging to PANGO lineage BA.1 provided the fundamental genome and served as the major parents, while the rare lineage strains like SARS-CoV-2/human/IRN/Ir-3/2019 belonging to B.35, as the minor parents, hybridized their genomic fractions into the major genomes at position 21593-23118nt. This recombination event results in 22 amino acid residue substitutions for the variant of Omicron, including 16 in the pivotal RBD of the spike protein. These substitutions have led to some subtle variations in the spatial structure and the affinity to hACE2 receptor of the spike protein 7,8 , thereby raising concerns about the effectiveness of available vaccines and antibody therapeutics 9–12 . The global spread and explosive growth of the SARS-CoV-2 in human population increase opportunities for future recombination 13–15 .

Quantum Dot-Conjugated SARS-CoV-2 Spike Nanoparticles for SARS-CoV-2 infection modeling and drug discovery

The SARS-CoV-2 virus binds to host cell surface ACE2 on the plasma membrane via the spike protein's receptor binding domain. Our work has resulted in the generation of a versatile imaging probe using recombinant Spike receptor binding domain conjugated to fluorescent quantum dots (QDs). This probe is capable of engaging in energy transfer quenching with ACE2-conjugated gold nanoparticles enabling biochemical monitoring of binding. Neutralizing antibodies and recombinant human ACE2 blocked quenching, demonstrating a specific binding interaction. In cell-based assays, we observed immediate binding of the probe on the cell surface of ACE2-expressing cells followed by endocytosis. Neutralizing antibodies and ACE2-Fc fully prevented binding and endocytosis with low nanomolar potency. Importantly, we can use this QD nanoparticle probe to identify and validate inhibitors of the SARS-CoV-2 Spike and ACE2 receptor binding in human cells. This work enables facile, rapid, and high-throughput biochemical- and cell-based screening of inhibitors for coronavirus Spike-mediated cell recognition and entry.

T-cell Repertoire Characteristics of Asymptomatic and Re-detectable Positive COVID-19 Patients (preprint)

Background: The prevention of COVID-19 pandemic is highly complicated by the prevalence of asymptomatic and recurrent infection. Many previous immunological studies have focused on symptomatic and convalescent patients, while the immune responses in asymptomatic patients and re-detectable positive cases remain unclear. Methods: Here we comprehensively analyzed the peripheral T-cell receptor (TCR) repertoire of 54 COVID-19 patients in different phases, including asymptomatic, symptomatic, convalescent and re-detectable positive cases. Results: We found progressed immune responses from asymptomatic to symptomatic phase. Furthermore, the TCR profiles of re-detectable positive cases were highly similar to those of asymptomatic patients, which could predict the risk of recurrent infection. Conclusion: Therefore, TCR repertoire surveillance has the potential to strengthen the clinical management and the immunotherapy development for COVID-19.

Analysis and Evaluation of International Information about Corona Virus Disease 2019 (COVID-19)

OBJECTIVE: To analyze and evaluate the international information about coronavirus disease 2019 (COVID-19), and provide reference for prevention and control of the epidemic. METHODS: International information about COVID-19 from World Health Organization (WHO), Centers for Disease Control and Prevention, US (CDC), European Centre for Disease Prevention and Control (ECDC), Department of Health, Australian Government (AGDH), Department of Health & Social Care, UK (UKDH), the International Pharmaceutical Federation (FIP) were retrieved and summarized. The timeliness, comprehensiveness and applicability of the international information were evaluated descriptively. Technical guidance about clinical management and pharmaceutical work of pharmacists were analyzed. RESULTS: Information from WHO, CDC, ECDC, AGDH, UKDH and FIP were generally detailed, with timeliness, comprehensiveness and a certain applicability. WHO focused on global perspective and provided clinical management guidance, and FIP focused on pharmacist and pharmaceutical work and provided information about clinical medication. CONCLUSION: When referring to international information about COVID-19, the actual situation should be taken into consideration, and subsequently the information should be applied cautiously to help prevent and control the epidemic of COVID-19.

High expression of angiotensin-converting enzyme-2 (ACE2) on tissue macrophages that may be targeted by virus SARS-CoV-2 in COVID-19 patients (preprint)

Angiotensin-converting enzyme-2 (ACE2) has been recognized as the binding receptor for the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that infects host cells, causing the development of the new coronavirus infectious disease (COVID-19). To better understand the pathogenesis of COVID-19 and build up the host anti-viral immunity, we examined the levels of ACE2 expression on different types of immune cells including tissue macrophages. Flow cytometry demonstrated that there was little to no expression of ACE2 on most of the human peripheral blood-derived immune cells including CD4+ T, CD8+ T, activated CD4+ T, activated CD8+ T, CD4+CD25+CD127low/- regulatory T cells (Tregs), Th17 cells, NKT cells, B cells, NK cells, monocytes, dendritic cells (DCs), and granulocytes. Additionally, there was no ACE2 expression (< 1%) found on platelets. Compared with interleukin-4-treated type 2 macrophages (M2), the ACE2 expression was markedly increased on the activated type 1 macrophages (M1) after the stimulation with lipopolysaccharide (LPS). Immunohistochemistry demonstrated that high expressions of ACE2 were colocalized with tissue macrophages, such as alveolar macrophages found within the lungs and Kupffer cells within livers of mice. Flow cytometry confirmed the very low level of ACE2 expression on human primary pulmonary alveolar epithelial cells. These data indicate that alveolar macrophages, as the frontline immune cells, may be directly targeted by the SARS-CoV-2 infection and therefore need to be considered for the prevention and treatment of COVID-19.

Analysis of clinical characteristics of SARS-CoV-2 infected cases: a retrospective study of medical records (preprint)

Objectives In order to identify the clinical characteristics of patients with Corona Virus Disease 2019 (COVID-19) and find out the characteristic effects of 2019 New Coronavirus (SARS-CoV-2) infection on changes in clinical and laboratory data. Patients and methods From January 22 to February 13, 2020, we enrolled consecutive patients with acute respiratory tract symptoms admitted to a hospital (Ezhou, Hubei, China). For different data types t-test, the variables associated with the diagnosis of COVID-19 were compared by chi-square test and u-test, the statistically significant variables (P-value<0.05) were selected into the final logistic regression model. Results 62 (77.5%) confirmed cases and 18 (22.5%) negative cases were confirmed by SARS-CoV-2 nucleic acid test. Epidemiological investigation and statistical analysis were carried out on the clinical and laboratory data of all suspected cases of COVID-19, the specific indicators were found, and the clinical characteristics of COVID-19 were described. Compared with the patients with negative nucleic acid test, the patients with positive nucleic acid test showed shorter time of onset of symptoms, higher plasma CO2 level, lower eosinophil ratio, lower platelet count and hematocrit, lower serum sodium level, higher serum creatinine, higher blood urea and plasma albumin levels (all P<0.05). Conclusions we argue that the SARS-CoV-2 infection can cause multiple organ damage to the heart, liver, kidney and bone marrow other than lung injury.

Analysis of clinical characteristics of SARS-CoV-2 infected cases: a retrospective study of medical records (preprint)

In order to identify the clinical characteristics of patients with Corona Virus Disease 2019 (COVID-19) and find out the characteristic effects of 2019 New Coronavirus (SARS-CoV-2) infection on changes in clinical and laboratory data, we analyzed the medical records of 80 suspected cases who admitted in the national designated hospital due to the relevant clinical manifestations of SARS-CoV-2 infection from January 22 to February 13, 2020. 62 (77.5%) confirmed cases and 18 (22.5%) negative cases were confirmed by SARS-CoV-2 nucleic acid test. Epidemiological investigation and statistical analysis were carried out on the clinical and laboratory data of all suspected cases of COVID-19, the specific indicators were found, and the clinical characteristics of COVID-19 were described. Compared with the patients with negative nucleic acid test, the patients with positive nucleic acid test showed shorter time of onset of symptoms, higher plasma CO2 level, lower eosinophil ratio, lower platelet count and hematocrit, lower serum sodium level, higher serum creatinine, higher blood urea and plasma albumin levels (all P<0.05). Our results might provide some suggestions in diagnosis, clinical treatment and prevention for COVID-19.

Countrywide quarantine only mildly increased anxiety level during COVID-19 outbreak in China (preprint)

In the recent outbreak of COVID-19, many countries have taken various kinds of quarantine measures to slow down the explosive spreading of COVID-19. Although these measures were proven to be successful in stopping the outbreak in China, the potential adverse effects of countrywide quarantine have not been thoroughly investigated. In this study, we performed an online survey to evaluate the psychological effects of quarantine in China using Zung Self-rating Anxiety Scale in February 2020 when the outbreak was nearly peaked in China. Along with the anxiety scores, limited personal information such as age, gender, region, education, occupation and specifically, the type and duration of quarantine were collected for analysis. For a total number of 992 valid questionnaires, clinical significance of anxiety symptoms was observed in 9.58% respondents according to clinical diagnostic standards in China. Statistical results showed population with different age, education level, health status and personnel category responded differently. Other characteristics such as gender, marital status, region, and acquaintance with suspected or confirmed cases of COVID-19 did not affect anxiety levels significantly. Respondents experienced different forms of quarantine showed different anxiety levels. Unexpectedly, longer durations of quarantine did not lead to significant increase of anxiety level. Our results suggest a rather mild psychological influence caused by the countrywide quarantine during COVID-19 outbreak in China and provided reference for other countries and regions to battle COVID-19.

Analysis of factors affected the SARS-CoV-2 viral shedding time of COVID-19 patients in Anhui, China: a retrospective study (preprint)

Background The epidemic of Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) has spread worldwide, but the factors that may affect the SARS-CoV-2 viral shedding time in coronavirus disease 2019 (COVID-19) patients were rarely reported. Methods We retrospectively recruited 40 confirmed common COVID-19 patients and classified them into two groups according to the SARS-CoV-2 viral shedding time (group A (less than 10 days) and group B (10 days or more)). The demographic, laboratory parameters and chest computed tomography (CT) features on admission and the 3 rd day after treatment were analyzed respectively. Results Fourteen patients were in group A and 26 patients in group B, the median SARS-CoV-2 viral shedding time of the two groups was 7 and 16 days respectively. Compared to the group A, the comorbidity, epidemiological risk history, serum glucose and CD4/8 on admission were significantly higher in the group B (P<0.05). On the 3 rd day after treatment, the group B got significantly higher IL-6, IL-2R, TNF-α and CD4/8, and lower platelet and CD8 + T lymphocyte counts than group A (P<0.05). Logistic regression analyses revealed that the higher epidemiological risk history, serum glucose and CD4/8 on admission were significantly associated with a longer SARS-CoV-2 viral shedding time (OR=7.5, 11.41, 9.21 respectively, P<0.05), as well as the higher TNF-α and lower CD8 + T lymphocytes on the 3 rd day after treatment (OR=2.36, 0.98 respectively, P<0.05). Conclusions Our study provides the evidence that the prolonged SARS-CoV-2 viral shedding time might be correlated with the patients’ epidemiological risk history, as well as the serum glucose and CD4/8 on admission, TNF-α and CD8 + T lymphocytes on the 3 rd day after treatment. Our result may help clinicians to distinguish the patients with a prolonged viral shedding time at the early stage.