Humoral immune response characteristics of the susceptible populations after the infection of SARS-CoV-2 BA.5 strain (preprint)

This study compared the humoral immune characteristics of children, elderly people, pregnant women, and adults infected with BA.5 and XBB strains in Guangzhou, China. It was found that binding and neutralizing antibodies the titers against distinct SARS-CoV-2 strains were low in the acute-phase sera of BA.5 infected patients, while the corresponding titers were significantly increased in the convalescent phase, the antibody titers against the Wuhan strain were the highest. Regardless of whether they were vaccinated, BA.5 infection did not induce high neutralizing antibodies against XBB. During the recovery phase, the titers of antiviral antibodies in the vaccinated population are more robust than those in the unvaccinated population. For BA.5 infections, the specific binding and neutralizing antibody titers in the children group were lower compared to other population groups. In the convalescence period of the disease, the titers of neutralizing antibodies against Wuhan, BA.5 and XBB strains induced by BA.5 infections are significantly correlated in pairs. XBB can induce a broader and balanced antiviral humoral immune response than BA.5 as a first-time infected strain. This finding can provide a reference for the judgment of the future epidemic law of SARS-CoV-2, and provide a scientific basis for developing novel COVID-19 vaccines, especially for discovering customized vaccines and immune strategies for different populations.

Summary of global surveillance data of infectious diseases in April 2022

In April 2022, a total of 69 infectious diseases were reported globally, affecting 232 countries and regions. Except for influenza, the top five infectious diseases affecting greatest number of countries and regions were COVID-19 (232), dengue fever (29), measles (25), cholera (11) and leptospirosis (9). The top five infectious diseases with highest case fatality rates were Ebola virus disease (100.0%), Crimean-Congo hemorrhagic fever (40.0%), Middle East Respiratory Syndrome (34.4%), Lassa fever (19.3%) and monkeypox (5.3%). The top five infectious diseases with greatest number of deaths were COVID-19, malaria, dengue fever, cholera and measles. The prevalent infectious diseases in Asia were COVID-19 and dengue fever, the prevalent infectious diseases in Africa were COVID-19, Ebola virus disease, cholera, yellow fever, Lassa fever, malaria and measles, the prevalent infectious diseases in America were COVID-19, dengue fever, chikungunya fever and Zika virus disease, the prevalent infectious disease in Europe were COVID-19 and acute hepatitis of unknown aetiology.

Preventive measures significantly reduced the risk of nosocomial infection in elderly inpatients during the COVID-19 pandemic

In December 2019, there was an outbreak of pneumonia of unknown causes in Wuhan, China. The etiological pathogen was identified to be a novel coronavirus, named severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2), which causes coronavirus disease 2019 (COVID-19). The number of infected patients has markedly increased since the 2019 outbreak and COVID-19 has also proven to be highly contagious. In particular, the elderly are among the group of patients who are the most susceptible to succumbing to COVID-19 within the general population. Cross-infection in the hospital is one important route of SARS-CoV-2 transmission, where elderly patients are more susceptible to nosocomial infections due to reduced immunity. Therefore, the present study was conducted to search for ways to improve the medical management workflow in geriatric departments to ultimately reduce the risk of nosocomial infection in elderly inpatients. The present observational retrospective cohort study analysed elderly patients who were hospitalised in the Geriatric Department of the First Affiliated Hospital with Nanjing Medical University (Nanjing, China). A total of 4,066 elderly patients, who were admitted between January and March in 2019 and 2020 and then hospitalised for >48 h were selected. Among them, 3,073 (75.58%) patients hospitalised from January 2019 to March 2019 were allocated into the non-intervention group, whereas the remaining 933 (24.42%) patients hospitalised from January 2020 to March 2020 after the COVID-19 outbreak were allocated into the intervention group. Following multivariate logistic regression analysis, the risk of nosocomial infections was found to be lower in the intervention group compared with that in the non-intervention group. After age stratification and adjustment for sex, chronic disease, presence of malignant tumour and trauma, both inverse probability treatment weighting and standardised mortality ratio revealed a lower risk of nosocomial infections in the intervention group compared with that in the non-intervention group. To rule out interference caused by changes in the community floating population and social environment during this 1-year study, 93 long-stay patients in stable condition were selected as a subgroup based on 4,066 patients. The so-called floating population refers to patients who have been in hospital for <2 years. Patients aged ≥65 years were included in the geriatrics program. The incidence of nosocomial infections during the epidemic prevention and control period (24 January 2020 to 24 March 2020) and the previous period of hospitalisation (24 January 2019 to 24 March 2019) was also analysed. In the subgroup analysis, a multivariate analysis was also performed on 93 elderly patients who experienced long-term hospitalisation. The risk of nosocomial and pulmonary infections was found to be lower in the intervention group compared with that in the non-intervention group. During the pandemic, the geriatric department took active preventative measures. However, whether these measures can be normalised to reduce the risk of nosocomial infections among elderly inpatients remain unclear. In addition, the present study found that the use of an indwelling gastric tube is an independent risk factor of nosocomial pulmonary infection in elderly inpatients. However, nutritional interventions are indispensable for the long-term wellbeing of patients, especially for those with dysphagia in whom an indwelling gastric tube is the most viable method of providing enteral nutrition. To conclude, the present retrospective analysis of the selected cases showed that enacting preventative and control measures resulted in the effective control of the incidence of nosocomial infections.

Summary of global surveillance data of infectious diseases in May 2021

In May 2021, a total of 67 infectious diseases were reported globally, affecting 225 countries and regions. Except for influenza, the top five infectious diseases affecting greatest number of countries and regions were corona virus disease 2019 (COVID-19, 225), dengue fever (30), measles (29), poliomyelitis (15) and malaria (9). The top five infectious diseases with highest case fatality rates were Ebola virus disease (52.2%), Middle East respiratory syndrome (34.4%), lassa fever (20.3%), plague (6.0%) and Crimean-Congo hemorrhagic fever (5.3%). The top five infectious diseases with greatest number of deaths were COVID-19, malaria, measles, dengue fever and cholera. The prevalent infectious diseases in Asia were COVID-19 and dengue fever, the prevalent infectious diseases in Africa were COVID-19, Ebola virus disease, plague, cholera, yellow fever, lassa fever and Rift valley fever, the prevalent infectious diseases in America were COVID-19 and dengue fever, the prevalent infectious disease in Europe was COVID-19.

Summary of global surveillance data of infectious diseases in April 2020

In April 2020, a total of 61 infectious diseases were reported globally, affecting 214 countries and regions. Except for influenza, the top five infectious diseases affecting greatest number of countries and regions were Novel coronavirus disease 2019(COVID-19)(214), measles (30), dengue fever (19), poliomyelitis (12) and rubella (9). The top four infectious diseases with highest case fatality rates were Ebola virus disease (65.8%), Middle East respiratory syndrome (34.2%), Lassa fever (19.0%) and COVID-19 (7.0%). The top five infectious diseases with greatest number of deaths were COVID-19, measles, dengue fever, cholera and Ebola virus disease. The prevalent infectious diseases in Asia were COVID-19, Middle East respiratory syndrome and dengue fever, the prevalent infectious diseases in Africa were COVID-19, Ebola virus disease, cholera, yellow fever, Lassa fever and measles, the prevalent infectious diseases in America were COVID-19 and dengue fever, the prevalent infectious diseases in Europe were COVID-19 and measles and measles.

Perceptions and Behavioral Adoptions of the Preventive Strategies from Person-to-Person Transmission of COVID-19 Among the Public in China: An Online Cross-Sectional Survey (preprint)

Background: The strategies adopted to prevent spreading of COVID-19 are quarantine, social distancing and isolation of infected cases. This study investigates perceptions and behavioral adoptions of COVID-19 prevention strategies among the Chinese public and identified factors predicting individual health behavior.Methods: We conducted a cross-sectional online survey between 22 February and 5 March, 2020. We approached to urban residents aged over 18 years through snowball sampling method using the Chinese social media. The Health Belief Model was adopted to guide the analysis. Bivariate and multivariate logistic regressions were used to examine impacts of modifying factors (including demographic and socio-economic characteristics) and individual beliefs on individual health behavior.Results: of 5675 valid questionnaires, 95.8% of the respondents well understood the preventive measures from COVID-19 transmission, while 79.9% of the respondents adopted the behavior advised. 45.7% of the respondents perceived severity of the disease, 75.6% of the respondents perceived benefits of social constraints measures and 62.7% reported anxiety during the epidemic. After adjusting for modifying factors and individual beliefs, those who were female, had better income and good knowledge on preventive measures, perceived benefits on social constraint measures and did not feel anxiety were more likely to adopt behaviors advised.Conclusions: The Chinese public highly accepted and adopted behaviors advised to slow down the COVID-19 epidemic. People with low income or feeling anxiety were less likely to adopt the behavior advised. The policy support should target on the social vulnerable groups. The psychological support should be disseminated through different means, and the consultation should be provided to those who are in need.

Perceptions and Behavioral Adoptions of the Preventive Strategies from Person-to-Person Transmission of COVID-19 among the Public in China: An Online Cross-Sectional Survey (preprint)

Background: The strategies adopted to prevent spreading of COVID-19 are quarantine, social distancing and isolation of infected cases. This study investigates perceptions and behavioral adoptions of COVID-19 prevention strategies among the Chinese public and identified factors predicting individual health behavior.Methods: We conducted a cross-sectional online survey between 22 February and 5 March, 2020. We approached to urban residents aged over 18 years through snowball sampling method using the Chinese social media. The Health Belief Model was adopted to guide the analysis. Bivariate and multivariate logistic regressions were used to examine impacts of modifying factors (including demographic and socio-economic characteristics) and individual beliefs on individual health behavior.Results: of 5675 valid questionnaires, 95.8% of the respondents well understood the preventive measures from COVID-19 transmission, while 79.9% of the respondents adopted the behavior advised. 45.7% of the respondents perceived severity of the disease, 75.6% of the respondents perceived benefits of social constraints measures and 62.7% reported anxiety during the epidemic. After adjusting for modifying factors and individual beliefs, those who were female, had better income and good knowledge on preventive measures, perceived benefits on social constraint measures and did not feel anxiety were more likely to adopt behaviors advised.Conclusions: The Chinese public highly accepted and adopted behaviors advised to slow down the COVID-19 epidemic. People with low income or feeling anxiety were less likely to adopt the behavior advised. The policy support should target on the social vulnerable groups. The psychological support should be disseminated through different means, and the consultation should be provided to those who are in need.

Control Strategies for COVID-19 Epidemic with Vaccination, Shield Immunity and Quarantine: A Metric Temporal Logic Approach (preprint)

Ever since the outbreak of the COVID-19 epidemic, various public health control strategies have been proposed and tested against the coronavirus SARS-CoV-2. We study three specific COVID-19 epidemic control models: the susceptible, exposed, infectious, recovered (SEIR) model with vaccination control; the SEIR model with shield immunity control; and the susceptible, un-quarantined infected, quarantined infected, confirmed infected (SUQC) model with quarantine control. We express the control requirement in metric temporal logic (MTL) formulas (a type of formal specification languages) which can specify the expected control outcomes such as "the deaths from the infection should never exceed one thousand per day within the next three months" or "the population immune from the disease should eventually exceed 200 thousand within the next 100 to 120 days". We then develop methods for synthesizing control strategies with MTL specifications. To the best of our knowledge, this is the first paper to systematically synthesize control strategies based on the COVID-19 epidemic models with formal specifications. We provide simulation results in three different case studies: vaccination control for the COVID-19 epidemic with model parameters estimated from data in Lombardy, Italy; shield immunity control for the COVID-19 epidemic with model parameters estimated from data in Lombardy, Italy; and quarantine control for the COVID-19 epidemic with model parameters estimated from data in Wuhan, China. The results show that the proposed synthesis approach can generate control inputs such that the time-varying numbers of individuals in each category (e.g., infectious, immune) satisfy the MTL specifications. The results also show that early intervention is essential in mitigating the spread of COVID-19, and more control effort is needed for more stringent MTL specifications.

The Relationship Between COVID-19 Infection and Risk Perception, Knowledge, Attitude As Well As Four Non-pharmaceutical Interventions (NPIs) During the Late Period Of The COVID-19 Epidemic In China An Online Cross-sectional Survey of 8158 Adults (preprint)

BackgroundSo far, there has been no published population study on the relationship between COVID-19 infection and publics risk perception, information source, knowledge, attitude and four non-pharmaceutical interventions(NPI: hand washing, proper coughing habits, social distancing and mask wearing) during the COVID-19 outbreak in China. MethodsAn online survey of 8158 Chinese adults between 22 February to 5 March 2020 was conducted. Bivariate associations between categorical variables were examined using Fisher exact test. We also explored the determinants of four NPIs as well as their association with COVID-19 infection using logistic regression. ResultsOf 8158 adults included, 57 (0.73%) were infected with COVID-19. The overwhelming majority of respondents showed a positive attitude (99.2%), positive risk perception (99.9%) and high knowledge levels that were among the strongest predictors of four highly adopted NPIs (hand washing:96.8%; proper coughing: 93.1%; social distancing:87.1%; mask wearing:97.9%). There was an increased risk of COVID-19 infection for those who not washing hands (2.28% vs 0.65%; RR=3.53: 95%CI: 1.53-8.15; P<0.009); not practicing proper coughing (1.79% vs 0.73%; RR=2.44: 95%CI: 1.15-5.15;P=0.026); not practicing social distancing (1.52% vs 0.58%; RR=2.63:95%CI:1.48 - 4.67; P=0.002); and not wearing a mask (7.41% vs 0.6%; RR=12.38:95%CI:5.81-26.36; P<0.001). For those who did practice all other three NPIs, wearing mask was associated with significantly reduced risk of infection compared to those who did not wear a mask (0.6% vs 16.7%; p=0.035). Similarly, for those who did not practice all or part of the other three NPIs, wearing mask was also associated with significantly reduced risk of infection. In a penalised logistic regression model including all four NPIs, wearing a mask was the only significant predictor of COVID-19 infection among four NPIs (OR=7.20; 95%CI:2.24-23.11; p<0.001). ConclusionsWe found high levels of risk perception, positive attitude, desirable knowledge as well as a high level of adopting four NPIs. The relevant knowledge, risk perception and attitude were strong predictors of adapting the four NPIs. Mask wearing, among four personal NPIs, was the most effective protective measure against COVID-19 infection with added preventive effect among those who practised all or part of the other three NPIs.

Incidence rate, clinical course and risk factor for recurrent PCR positivity in discharged COVID-19 patients in Guangzhou, China: a prospective cohort study (preprint)

Background: The phenomenon of COVID-19 patients tested positive for SARS-CoV-2 after discharge (redetectable as positive, RP) emerged globally. The data of incidence rate and risk factors for RP event and the clinical features of RP patients may provide recommendations for virus containment and discharge assessment for COVID-19. Methods: The baseline included 285 adult inpatients (≥18 years old) with laboratory-confirmed COVID-19 from Guangzhou Eighth People's Hospital. We started the Observation on Jan 20, 2020, and acquired all their definite clinical outcome (becoming RP or keeping normal during post-discharge surveillance) by Mar 10, 2020. The dynamic clinical data of patients during observation were prospectively collected and analyzed. Univariate and multivariate-adjusted logistic regression were used to explore the risk factors related to RP events in COVID-19 patients. Results: By March 10, 27 (9.5%) discharged patients had tested positive for SARS-CoV-2 in their nasopharyngeal swab after a median duration of 7·0 days (IQR 5·0-8·0). Age, sex, epidemiological history, clinical symptoms and underlying diseases were similar between RP and non-RP patients (p>0.05). Compared to first admission, RP patients generally had milder clinical symptoms, lower viral load, shorter length of stay and improved pulmonary conditions at readmission (p<0.05). Elder RP patients (≥ 60 years old) were more likely to be symptomatic compared to younger patients (7/8, 87.5% vs. 3/19, 18.8%, p=0.001) at readmission. A prolonged duration of viral shedding (>10 days) during the first hospitalization [adjusted odds ratio [aOR]: 5.82, 95% confidence interval [CI]: 2.50-13.57 for N gene; aOR: 9.64, 95% CI: 3.91-23.73 for ORF gene] and higher Ct value (ORF) in the third week of the first hospitalization (aOR: 0.69; 95% CI: 0.50-0.95) were associated with RP events. Conclusions: RP events occurred in nearly 10% of COVID-19 patients which deserves globally attention. During hospitalization, patients’ low efficiency of viral clearance was a risk factor for RP event. Elderly RP patients were more likely to develop clinical symptoms. To reduce the possibility of reinfection and readmission during the management of COVID-19, more rigorously monitoring on patients’ viral load should be carried out especially in elder patients and later stage of hospitalization.

First Case of COVID-19 Complicated with Fulminant Myocarditis: A case Report and Insights (preprint)

Background: Coronavirus Disease 2019 (COVID-19) has been demonstrated to be the cause of pneumonia. Nevertheless, it has not been reported as the cause of acute myocarditis or fulminant myocarditis. Case presentation: A 63-year-old male was admitted with pneumonia and cardiac symptoms. He was genetically confirmed as having COVID-19 according to sputum testing on the day of admission. He also had elevated troponin I (Trop I) level (up to 11.37 g/L) and diffuse myocardial dyskinesia along with a decreased left ventricular ejection fraction (LVEF) on echocardiography. The highest level of interleukin-6 was 272.40 pg/ml. Bedside chest radiographs showed typical ground-glass changes indicative of viral pneumonia. Laboratory test results for viruses that cause myocarditis were all negative. The patient conformed to the diagnostic criteria of the Chinese expert consensus statement for fulminant myocarditis. After receiving antiviral therapy and mechanical life support, Trop I was reduced to 0.10 g/L, and interleukin-6 was reduced to 7.63 pg/ml. Moreover, the LVEF of the patient gradually recovered to 68%. The patient died of aggravation of secondary infection on the 33rd day of hospitalization. Conclusion: COVID-19 patients may develop severe cardiac complications such as myocarditis and heart failure. This is the first report of COVID-19 complicated with fulminant myocarditis. The mechanism of cardiac pathology caused by COVID-19 needs further study.

Modes of contact and risk of transmission in COVID-19 among close contacts (preprint)

Background Rapid spread of SARS-CoV-2 in Wuhan prompted heightened surveillance in Guangzhou and elsewhere in China. Modes of contact and risk of transmission among close contacts have not been well estimated. Methods We included 4950 closes contacts from Guangzhou, and extracted data including modes of contact, laboratory testing, clinical characteristics of confirmed cases and source cases. We used logistic regression analysis to explore the risk factors associated with infection of close contacts. Results Among 4950 closes contacts, the median age was 38.0 years, and males accounted for 50.2% (2484). During quarantine period, 129 cases (2.6%) were diagnosed, with 8 asymptomatic (6.2%), 49 mild (38.0%), and 5 (3.9%) severe to critical cases. The sensitivity of throat swab was 71.32% and 92.19% at first to second PCR test. Among different modes of contact, household contacts were the most dangerous in catching with infection of COVID-19, with an incidence of 10.2%. As the increase of age for close contacts and severity of source cases, the incidence of COVID-19 presented an increasing trend from 1.8% (0-17 years) to 4.2% (60 or over years), and from 0.33% for asymptomatic, 3.3% for mild, to 6.2% for severe and critical source cases, respectively. Manifestation of expectoration in source cases was also highly associated with an increased risk of infection in their close contacts (13.6%). Secondary cases were in general clinically milder and were less likely to have common symptoms than those of source cases. Conclusions In conclusion, the proportion of asymptomatic and mild infections account for almost half of the confirmed cases among close contacts. The household contacts were the main transmission mode, and clinically more severe cases were more likely to pass the infection to their close contacts. Generally, the secondary cases were clinically milder than those of source cases.

Antibody responses to SARS-CoV-2 in COVID-19 patients: the perspective application of serological tests in clinical practice (preprint)

Background We aim to investigate the profile of acute antibody response in COVID-19 patients, and provide proposals for the usage of antibody test in clinical practice. Methods A multi-center cross-section study (285 patients) and a single-center follow-up study (63 patients) were performed to investigate the feature of acute antibody response to SARS-CoV-2. A cohort of 52 COVID-19 suspects and 64 close contacts were enrolled to evaluate the potentiality of the antibody test. Results The positive rate for IgG reached 100% around 20 days after symptoms onset. The median day of serocon-version for both lgG and IgM was 13 days after symptoms onset. Seroconversion of IgM occurred at the same time, or earlier, or later than that of IgG. IgG levels in 100% patients (19/19) entered a platform within 6 days after seroconversion. The criteria of IgG seroconversion and [≥] 4-fold increase in the IgG titers in sequential samples together diagnosed 82.9% (34/41) of the patients. Antibody test aided to confirm 4 patients with COVID-19 from 52 suspects who failed to be confirmed by RT-PCR and 7 patients from 148 close contacts with negative RT-PCR. Conclusion IgM and IgG should be detected simultaneously at the early phase of infection. The serological diagnosis criterion of seroconversion or [≥] 4-fold increase in the IgG titer is suitable for a majority of COVID-19 patients. Serologic test is helpful for the diagnosis of SARS-CoV-2 infection in suspects and close contacts.

First Case of COVID-19 Infection with Fulminant Myocarditis Complication: Case Report and Insights (preprint)

Background: The Coronavirus Disease 2019 (COVID-19) has been demonstrated as the cause of pneumonia. Nevertheless, it has not been reported as the cause of acute myocarditis or fulminant myocarditis. Case Presentation: A 63-year-old male was admitted with pneumonia and cardiac symptoms. He was genetically confirmed as COVID-19 by testing sputum on the first day of admission. He also had an elevated troponin-I (Trop I) level and diffuse myocardial dyskinesia along with decreased left ventricular ejection fraction (LVEF) on echocardiography. The highest level of Interleukin 6 was 272.40pg/ml. Bedside chest radiograph had typical ground-glass changes of viral pneumonia. The laboratory test results of virus that can cause myocarditis are all negative. The patient conformed to the diagnostic criteria of Chinese expert consensus statement for fulminant myocarditis. After receiving antiviral therapy and mechanical life support, the Trop I reduced to 0.10 g/L, and Interleukin 6 was 7.63 pg/ml. Meanwhile the LVEF of the patient gradually recovered to 68%. Conclusion: COVID-19 patients may develop severe cardiac complications such as myocarditis and heart failure, and this is the first case of COVID-19 infection complicated with fulminant myocarditis. The mechanism of cardiac pathology caused by COVID-19 needs further study.