Linking sporadic hospital clusters during a community surge of the severe acute respiratory coronavirus virus 2 (SARS-CoV-2) B.1.617.2 delta variant: The utility of whole-genome sequencing.

Sporadic clusters of healthcare-associated coronavirus disease 2019 (COVID-19) occurred despite intense rostered routine surveillance and a highly vaccinated healthcare worker (HCW) population, during a community surge of the severe acute respiratory coronavirus virus 2 (SARS-CoV-2) B.1.617.2 δ (delta) variant. Genomic analysis facilitated timely cluster detection and uncovered additional linkages via HCWs moving between clinical areas and among HCWs sharing a common lunch area, enabling early intervention.

How influenza vaccination changed over the COVID-19 pandemic? (preprint)

Background: Vaccination for seasonal influenzas is particularly important during the COVID-19 pandemic, but the influenza vaccination coverage in the U.S. was far lower than the targeted rate. Objective: To examine how people's actual uptake of the influenza vaccine and the disparity of the vaccination changed during the pandemic. Methods: A survey was conducted online in November 2022. Respondents were asked for influenza vaccination during each of the three latest seasons, prior influenza vaccination history, and COVID-19 vaccination. A linear regression model was used to estimate how the respondents' change in influenza vaccination was associated with their demographics, COVID-19 vaccination status, and other related variables. Results: Nearly 70% of US adults had influenza vaccine each season during past the three seasons of the COVID-19 pandemic. The prevalence of influenza vaccination varied markedly across demographics. Non-Hispanic Black, Hispanic, and people with low educational attainment were more likely to see relatively negative changes in their level of influenza vaccination. Respondents who uptook their COVID-19 vaccine in 2022 increased their level of influenza vaccine more than those who uptook the vaccine in 2021. Conclusions: Our study indicated that influenza vaccination increased during the pandemic compared with before the pandemic. The disparity of influenza vaccination by race/ethnicity and socioeconomic status may enlarge during the pandemic. Tailored interventions were needed to target some groups to promote their vaccination uptake.

Has the COVID-19 pandemic ended or not? opinions from the public in the U.S. (preprint)

Recently President Joe Biden announced the end to the COVID-19 pandemic in the US but some scientists expressed different opinions. This study aimed to examine the view of the end of the COVID-19 pandemic among the public. Data were collected in September 2022 from an online crowdsourcing platform, and respondents answered if they believed that the pandemic has ended in the United States or not. Logistic regressions were used to estimate the likelihood of agreeing on the end of the pandemic, adjusted by demographics and several related variables. Among 2983 respondents, 78.1% believed that the COVID-19 pandemic had ended, and the percentage decreased to 66.5% after adding weights. Males, younger adults, Hispanics, those with higher levels of educational attainment, those with middle levels of household income, those living in suburban or rural areas, and those living in states that voted for the Republican party in the 2020 Presidential Election were more likely to believe that the pandemic had ended, compared with their counterparts. With about one-third of Americans did not agree that the pandemic had ended and marked demographical and geographical differences, the timing and the way of the pandemic end announcement should be deliberately cautious.

A multispecific antibody confers pan-reactive SARS-CoV-2 neutralization and prevents immune escape (preprint)

Continued evolution of the SARS-CoV-2 spike poses a challenge to immune interventions. To develop antibodies that protect against evolving SARS-CoV-2 viruses, we combined antibodies that recognize different RBD sites to generate a trivalent antibody that potently neutralized all major variants, including the most recent Omicron lineages. Negative stain electron microscopy suggests that this multispecific achieves synergistic neutralization by engaging different epitopes in specific orientations that facilitate inter-spike binding. These interactions resulted in not only improved potency but also importantly prevented virus escape, a feature not seen with parental antibody cocktails or the most potent clinical mAb. Such multispecific antibodies simplify treatment, maximize coverage, decrease the likelihood of SARS-CoV-2 escape, and provide the basis for building universal SARS-CoV-2 antibody therapies that are more likely to maintain broad reactivity for future variants.

Dengue and COVID-19: Managing Undifferentiated Febrile Illness during a "Twindemic".

BACKGROUND: During the COVID-19 pandemic, distinguishing dengue from COVID-19 in endemic areas can be difficult, as both may present as undifferentiated febrile illness. COVID-19 cases may also present with false-positive dengue serology. Hospitalisation protocols for managing undifferentiated febrile illness are essential in mitigating the risk from both COVID-19 and dengue. METHODS: At a tertiary hospital contending with COVID-19 during a dengue epidemic, a triage strategy of routine COVID-19 testing for febrile patients with viral prodromes was used. All febrile patients with viral prodromes and no epidemiologic risk for COVID-19 were first admitted to a designated ward for COVID-19 testing, from January 2020 to December 2021. RESULTS: A total of 6103 cases of COVID-19 and 1251 cases of dengue were managed at our institution, comprising a total of 3.9% (6103/155,452) and 0.8% (1251/155,452) of admissions, respectively. A surge in dengue hospitalisations in mid-2020 corresponded closely with the imposition of a community-wide lockdown. A total of 23 cases of PCR-proven COVID-19 infection with positive dengue serology were identified, of whom only two were true co-infections; both had been appropriately isolated upon admission. Average length-of-stay for dengue cases initially admitted to isolation during the pandemic was 8.35 days (S.D. = 6.53), compared with 6.91 days (S.D. = 8.61) for cases admitted outside isolation (1.44 days, 95%CI = 0.58-2.30, p = 0.001). Pre-pandemic, only 1.6% (9/580) of dengue cases were admitted initially to isolation-areas; in contrast, during the pandemic period, 66.6% (833/1251) of dengue cases were initially admitted to isolation-areas while awaiting the results of SARS-CoV-2 testing. CONCLUSIONS: During successive COVID-19 pandemic waves in a dengue-endemic country, coinfection with dengue and COVID-19 was uncommon. Routine COVID-19 testing for febrile patients with viral prodromes mitigated the potential infection-prevention risk from COVID-19 cases, albeit with an increased length-of-stay for dengue hospitalizations admitted initially to isolation.

Sporadic outbreaks of healthcare-associated COVID-19 infection in a highly-vaccinated inpatient population during a community outbreak of the B.1.617.2 variant: The role of enhanced infection-prevention measures.

Sporadic clusters of health care-associated COVID-19 infection occurred in a highly vaccinated health care-workers and patient population, over a 3-month period during ongoing community transmission of the B.1.617.2 variant. Enhanced infection-prevention measures and robust surveillance systems, including routine-rostered-testing of all inpatients and staff and usage of N95-respirators in all clinical areas, were insufficient in achieving zero health care-associated transmission. The unvaccinated and immunocompromised remain at-risk and should be prioritized for enhanced surveillance.

Efficacy of ancestral receptor-binding domain, S1 and trimeric spike protein vaccines against SARS-CoV-2 variants B.1.1.7, B.1.351, and B.1.617.1 (preprint)

The ongoing coronavirus disease 2019 (COVID-19) pandemic is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The current SARS-CoV-2 vaccines are based on spike (S) protein, S1 subunit, or receptor-binding domain (RBD) of prototype strain. Emergence of several novel SARS-CoV-2 variants has raised concern about potential immune escape. In this study, we performed an immunogenicity comparison of ancestral RBD, S1, and S ectodomain trimer (S-trimer) antigens and tested the efficacy of these prototype vaccines against the circulating variants, especially B.1.617 that has been linked to India's current COVID-19 surge. We found that RBD and S-trimer proteins could induce significantly higher neutralizing antibody titers than S1 protein. For the three vaccines, the neutralizing titers decreased over time, but still remained high for at least five months after immunization. Importantly, the three prototype vaccines were still effective in neutralizing the variants of concern, although B.1.351 and B.1.617.1 lineages showed varying degrees of reduction in neutralization by the immune sera. The vaccines-induced sera were shown to block receptor binding and inhibit S protein-mediated membrane fusion. In addition, the immune sera did not promote antibody-dependent enhancement (ADE) in vitro. Our work provides valuable information for development of SARS-CoV-2 subunit vaccines and also supports the continued use of ancestral RBD or S-based vaccines to fight the COVID-19 epidemic.

Toll-Like Receptor Agonist R848 Protects Mice from Lethal SARS-CoV-2 Infections (preprint)

Background: An ideal animal model to study SARS-coronavirus 2 (SARS-CoV-2) pathogenesis and evaluate therapies and vaccines should reproduce SARS-CoV-2 infection and recapitulate lung disease like those seen in humans. The angiotensin-converting enzyme 2 (ACE2) is a functional receptor for SARS-CoV-2, but mice are resistant to the infection because their ACE2 is incompatible with the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein. Methods: We generated a mouse-adapted strain SARS-CoV-2 by serial passages in the lung of BALB/c mice. Complete genome deep sequencing of different generations of viruses was performed to characterize the dynamics of the adaptive mutations in SARS-CoV-2. Indirect immunofluorescence analysis and Biolayer interferometry experiments demonstrated that two mutations in RBD significantly increased its binding affinity towards mouse ACE2. Significantly, TLR7/8 agonist Resiquimod block SARS-CoV-2 in vitro and in vivo. Findings: We adapted a wild-type SARS-CoV-2 by serial passages in the lung of BALB/c mice. The mouse-adapted strain WBP-1 showed increased infectivity in BALB/c mice and led to severe interstitial pneumonia. We characterized the dynamics of the adaptive mutations in SARS-CoV-2 and demonstrated that Q493K and Q498H in RBD significantly increased its binding affinity towards mouse ACE2. Additionally, The TLR7/8 agonist Resiquimod was able to protect mice against WBP-1 challenge, demonstrating this mouse-adapted strain is a useful tool to investigate COVID-19 and develop new therapies. Interpretation: We found for the first time that the Q493K and Q498H mutations in the RBD of WBP-1 enhanced its interactive affinities with mACE2. The mouse-adapted SARS-CoV-2 provides a valuable tool for the evaluation of novel antiviral and vaccine strategies, especially in determining the immunopathological consequences of any intervention. This study also verified the antiviral activity of TLR7/8 agonist Resiquimod against SARS-CoV-2 in vitro and in vivo.Funding Statement: This research was funded by Emergency Science and Technology Project of Hubei Province（2020FCA046）and Independent Science and Technology Innovation Fund of Huazhong Agricultural University in 2020 (2662020PY002).Declaration of Interests: The authors declare no competing interests.Ethics Approval Statement: The animal experiments were approved by the Research Ethics Committee, Huazhong Agricultural University, Hubei, China (HZAUMO-2020-0007). All the animal experiments were conducted in accordance with the recommendations in the Guide for the Care and Use of Laboratory Animals from the Research Ethics Committee, Huazhong Agricultural University, Hubei, China.

The differences of clinical characteristics and outcomes between imported and local patients of COVID-19 in Hunan: A two-center retrospective study (preprint)

Background: The clinical characteristics and outcomes of the 2019 novel coronavirus (COVID-19) pneumonia are different in Hubei compared to other regions in China. But there are few comparative studies on the differences between imported and local patients which may provide information of the different courses of the virus after transmission. Methods: : We investigated 169 cases of COVID-19 pneumonia in two centers in Hunan Province, and divided them into two groups according to epidemiological history, "imported patients" refers to patient with a clear history of travel in Wuhan within 14 days before onset, and " local patients” refers to local resident without a recent history of travel in Wuhan, aiming to analyze the difference in clinical characteristics and outcomes between the two groups. All the epidemiological, clinical, imaging, and laboratory data were analyzed and contrasted. Results: : The incidence of fever on admission in imported patients was significantly higher than local patients. There was a significantly higher proportion of abnormal pulmonary signs, hypokalemia, hyponatremia, prolonged PT, elevated D-dimer and elevated blood glucose in imported patients. Compared with local patients, the proportion using antibiotics, glucocorticoids and gamma globulin were significantly higher in imported patients. The moderate type was more common in local patients, and the severe type were more frequent in imported patients. In addition, the median duration of viral clearance was longer in imported patients. Conclusions: : In summary, we found that imported cases were more likely to develop into severe cases, compared with local patients and required more powerful treatments. Trial registration: Registered 21 st March 2020, and this study has been approved by the Medical Ethics Committee (Approved Number. 2020017).

Clinical characteristics of pediatric cases of SARS-CoV-2 infection in Hunan, China: A retrospective, multi-center case series (preprint)

Objective To investigate the epidemiological characteristics, clinical features, treatment and short-term prognosis of SARS-CoV-2 infection in children.Methods A retrospective analysis was conducted in children with SARS-CoV-2 admitted to twelve hospitals in eight cities in Hunan province, China, from January 26, 2020 to June 30, 2020.Results A total of 48 children were enrolled in this study. 11 cases (23%) were asymptomatic, 15 cases (31%) were mild, 20 cases (42%) were moderate, and 2 cases (4%) were severe. No children were critical requiring intensive care. The most common symptom was fever (42%), cough (40%), fatigue (17%) and diarrhea (10%). The total peripheral blood leukocytes count decreased in two case (4%), Lymphocytopenia was present in 5 cases (10%). There were abnormal chest CT changes in 22 children (46%), including 15 (68%) with patchy ground glass opacity. In addition to supportive treatment, 41 children (85%) received antiviral therapy, 11 patients and (23%) were treated with antibiotics, 2 children (4%) were treated with methylprednisolone and IVIG. There was no death occurred.Conclusions Most children with SARS CoV-2 infection in Hunan province were asymptomatic, mild or moderate. Severe cases are rare. Close family contact was the main route of infection. The younger the age, the less obvious symptoms for children might be. Epidemiological history, nucleic acid test and chest imaging were important tools for the diagnosis in children.

Conformational dynamics of SARS-CoV-2 trimeric spike glycoprotein in complex with receptor ACE2 revealed by cryo-EM (preprint)

The recent outbreaks of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its rapid international spread pose a global health emergency. The trimeric spike (S) glycoprotein interacts with its receptor human ACE2 to mediate viral entry into host-cells. Here we present cryo-EM structures of an uncharacterized tightly closed SARS-CoV-2 S-trimer and the ACE2-bound-S-trimer at 2.7-Å and 3.8-Å-resolution, respectively. The tightly closed S-trimer with inactivated fusion peptide may represent the ground prefusion state. ACE2 binding to the up receptor-binding domain (RBD) within S-trimer triggers continuous swing-motions of ACE2-RBD, resulting in conformational dynamics of S1 subunits. Noteworthy, SARS-CoV-2 S-trimer appears much more sensitive to ACE2-receptor than SARS-CoV S-trimer in terms of receptor-triggered transformation from the closed prefusion state to the fusion-prone open state, potentially contributing to the superior infectivity of SARS-CoV-2. We defined the RBD T470-T478 loop and residue Y505 as viral determinants for specific recognition of SARS-CoV-2 RBD by ACE2, and provided structural basis of the spike D614G-mutation induced enhanced infectivity. Our findings offer a thorough picture on the mechanism of ACE2-induced conformational transitions of S-trimer from ground prefusion state towards postfusion state, thereby providing important information for development of vaccines and therapeutics aimed to block receptor binding.Competing Interest StatementThe authors have declared no competing interest.View Full Text

Immunization with the receptor-binding domain of SARS-CoV-2 elicits antibodies cross-neutralizing SARS-CoV-2 and SARS-CoV without antibody-dependent enhancement (preprint)

Recently emerged severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the pathogen responsible for the ongoing coronavirus disease 2019 (COVID-19) pandemic. Currently, there is no vaccine available for preventing SARS-CoV-2 infection. Like closely related severe acute respiratory syndrome coronavirus (SARS-CoV), SARS-CoV-2 also uses its receptor-binding domain (RBD) on the spike (S) protein to engage the host receptor, human angiotensin-converting enzyme 2 (ACE2), facilitating subsequent viral entry. Here we report the immunogenicity and vaccine potential of SARS-CoV-2 RBD (SARS2-RBD)-based recombinant proteins. Immunization with SARS2-RBD recombinant proteins potently induced a multi-functional antibody response in mice. The resulting antisera could efficiently block the interaction between SARS2-RBD and ACE2, inhibit S-mediated cell-cell fusion, and neutralize both SARS-CoV-2 pseudovirus entry and authentic SARS-CoV-2 infection. In addition, the anti-RBD sera also exhibited cross binding, ACE2-blockade, and neutralization effects towards SARS-CoV. More importantly, we found that the anti-RBD sera did not promote antibody-dependent enhancement of either SARS-CoV-2 pseudovirus entry or authentic virus infection of Fc receptor-bearing cells. These findings provide a solid foundation for developing RBD-based subunit vaccines for SARS-CoV2.

Systematic investigations of COVID-19 in 283 cancer patients (preprint)

Background: Cancer patients are considered to be highly susceptible to viral infections, however, the comprehensive features of COVID-19 in these patients remained largely unknown. The present study aimed to assess the clinical characteristics and outcomes of COVID-19 in a large cohort of cancer patients. Design, Setting, and Participants: Data of consecutive cancer patients admitted to 33 designated hospitals for COVID-19 in Hubei province, China from December 17, 2019 to March 18, 2020 were retrospectively collected. The follow-up cutoff date was April 02, 2020. The clinical course and survival status of the cancer patients with COVID-19 were measured, and the potential risk factors of severe events and death were assessed through univariable and multivariable analyses. Results: A total of 283 laboratory confirmed COVID-19 patients (50% male; median age, 63.0 years [IQR, 55.0 to 70.0]) with more than 20 cancer types were included. The overall mortality rate was 18% (50/283), and the median hospitalization stay for the survivors was 26 days. Amongst all, 76 (27%) were former cancer patients with curative resections for over five years without recurrence. The current cancer patients exhibited worse outcomes versus former cancer patients (overall survival, HR=2.45, 95%CI 1.10 to 5.44, log-rank p=0.02; mortality rate, 21% vs 9%). Of the 207 current cancer patients, 95 (46%) have received recent anti-tumor treatment, and the highest mortality rate was observed in the patients receiving recent chemotherapy (33%), followed by surgery (26%), other anti-tumor treatments (19%), and no anti-tumor treatment (15%). In addition, a higher mortality rate was observed in patients with lymphohematopoietic malignancies (LHM) (53%, 9/17), and all seven LHM patients with recent chemotherapy died. Multivariable analysis indicated that LHM (p=0.001) was one of the independent factors associating with critical illness or death. Conclusions: This is the first systematic study comprehensively depicting COVID-19 in a large cancer cohort. Patients with tumors, especially LHM, may have poorer prognosis of COVID-19. Additional cares are warranted and non-emergency anti-tumor treatment should be cautiously used for these patients under the pandemic.