Monospecific and bispecific monoclonal SARS-CoV-2 neutralizing antibodies that maintain potency against B.1.617.

COVID-19 pathogen SARS-CoV-2 has infected hundreds of millions and caused over 5 million deaths to date. Although multiple vaccines are available, breakthrough infections occur especially by emerging variants. Effective therapeutic options such as monoclonal antibodies (mAbs) are still critical. Here, we report the development, cryo-EM structures, and functional analyses of mAbs that potently neutralize SARS-CoV-2 variants of concern. By high-throughput single cell sequencing of B cells from spike receptor binding domain (RBD) immunized animals, we identify two highly potent SARS-CoV-2 neutralizing mAb clones that have single-digit nanomolar affinity and low-picomolar avidity, and generate a bispecific antibody. Lead antibodies show strong inhibitory activity against historical SARS-CoV-2 and several emerging variants of concern. We solve several cryo-EM structures at ~3 Å resolution of these neutralizing antibodies in complex with prefusion spike trimer ectodomain, and reveal distinct epitopes, binding patterns, and conformations. The lead clones also show potent efficacy in vivo against authentic SARS-CoV-2 in both prophylactic and therapeutic settings. We also generate and characterize a humanized antibody to facilitate translation and drug development. The humanized clone also has strong potency against both the original virus and the B.1.617.2 Delta variant. These mAbs expand the repertoire of therapeutics against SARS-CoV-2 and emerging variants.

Influence of Pennsylvania liquor store closures during the COVID-19 pandemic on alcohol withdrawal consultations.

INTRODUCTION: Alcohol withdrawal syndrome (AWS) is a serious consequence of alcohol use disorder (AUD). Due to the current COVID-19 pandemic there was a closure of Pennsylvania (PA) liquor stores on March 17, 2020. METHODS: This is a retrospective, observational study of AWS patients presenting to a tertiary care hospital. We used descriptive statistics for continuous and categorical variables and compared AWS consults placed to the medical toxicology service for six months preceding liquor store closure to those placed between March 17, 2020 and August 31, 2020. We compared this to consults placed to the medical toxicology service placed from October 1, 2019 through March 16, 2020. Charts were identified based on consults placed to the medical toxicology service, and alcohol withdrawal was determined via chart review by a medical toxicologist. This study did not require IRB approval. We evaluated Emergency Department (ED) length of stay (LOS), weekly and monthly consultation rate, rate of admission and ED recidivism, both pre- and post-liquor store closure. RESULTS: A total of 324 AWS consults were placed during the ten month period. 142 (43.8%) and 182 (56.2%) consults were pre- and post-liquor store closure. The number of consults was not statistically significant comparing these two time frames. There was no significant difference by patient age, gender, or race or by weekly or monthly consultation rate when comparing pre- and post-liquor store periods. The median ED LOS was 7 h (95% Confidence Interval (CI) Larson et al. (2012), Pollard et al. (2020) [5, 11]) and did not significantly differ between pre- and post-liquor store periods (p = 0.78). 92.9% of AWS patients required admission without significant difference between the pre- and post-liquor store closure periods (94.4% vs. 91.8%, p = 0.36). There was a significant increase in the number of AWS patients requiring a return ED visit (Odds Ratio 2.49; 95% CI [1.38, 4.49]) post closure. CONCLUSION: There were nearly 2.5 times greater odds of ED recidivism among post-liquor store closure AWS patients compared with pre-closure AWS patients.

Rapid, reliable, and reproducible cell fusion assay to quantify SARS-Cov-2 spike interaction with hACE2.

COVID-19 is a global crisis of unimagined dimensions. Currently, Remedesivir is only fully licensed FDA therapeutic. A major target of the vaccine effort is the SARS-CoV-2 spike-hACE2 interaction, and assessment of efficacy relies on time consuming neutralization assay. Here, we developed a cell fusion assay based upon spike-hACE2 interaction. The system was tested by transient co-transfection of 293T cells, which demonstrated good correlation with standard spike pseudotyping for inhibition by sera and biologics. Then established stable cell lines were very well behaved and gave even better correlation with pseudotyping results, after a short, overnight co-incubation. Results with the stable cell fusion assay also correlated well with those of a live virus assay. In summary we have established a rapid, reliable, and reproducible cell fusion assay that will serve to complement the other neutralization assays currently in use, is easy to implement in most laboratories, and may serve as the basis for high throughput screens to identify inhibitors of SARS-CoV-2 virus-cell binding and entry.

A Dual-Antigen Enzyme-Linked Immunosorbent Assay Allows the Assessment of Severe Acute Respiratory Syndrome Coronavirus 2 Antibody Seroprevalence in a Low-Transmission Setting.

Estimates of seroprevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies have been hampered by inadequate assay sensitivity and specificity. Using an enzyme-linked immunosorbent assay-based approach that combines data about immunoglobulin G responses to both the nucleocapsid and spike receptor binding domain antigens, we show that excellent sensitivity and specificity can be achieved. We used this assay to assess the frequency of virus-specific antibodies in a cohort of elective surgery patients in Australia and estimated seroprevalence in Australia to be 0.28% (95% Confidence Interval, 0-1.15%). These data confirm the low level of transmission of SARS-CoV-2 in Australia before July 2020 and validate the specificity of our assay.

Singapore's Pandemic Preparedness: An Overview of the First Wave of COVID-19.

A global response to the rapid spread of the 2019 novel coronavirus disease (COVID-19) is imperative in order to reduce mortality and morbidity as well as preventing a country's health system from collapse. Singapore showed exceptional leadership in the containment of the spread of the virus, however through April 2020 the country experienced exponential growth in the number of infections, particularly migrant workers living in dormitories. The following historical case study provides an overview of Singapore's country profile, their healthcare system and the country's non pharmaceutical measures taken to mitigate and contain the spread of COVID-19 in the first few months of the pandemic. We explore the impact COVID-19 had on Singapore's economy at that time and the implications of the resultant social and political disruptions. We conclude our study by using mathematical modelling to explore confirmed COVID-19 cases in Singapore's local community and those living in dormitories and use this data to forecast the progression of the epidemic in Singapore given the non-pharmaceutical interventions in place at that time. Our results indicate the COVID-19 outbreak in Singapore increased 3-fold the initial doubling rate of 22.5 days in the first 2 months of the outbreak to 6.7 days in the 5th month; We note a faster doubling rate of 4.9 days for those living in dormitories compared to a doubling rate of 13.5 days for the rest of the community.

COVID-19 Down Under: Australia's Initial Pandemic Experience.

The following case study aims to provide a broad overview of the initial Australian epidemiological situation of the novel coronavirus disease (COVID-19) pandemic. We provide a case presentation of Australia's current demographic characteristics and an overview of their health care system. The data we present on Australia's COVID-19 situation pertain to the initial wave of the pandemic from January through to 20 April 2020. The results of our study indicate the number of reported COVID-19 cases in Australia reduced, and Australia initially managed to successfully flatten the curve-from an initial doubling time of 3.4 days at the end of March 2020 to a doubling time of 112 days as of 20 April 2020. Using SEIR mathematical modelling, we investigate a scenario assuming infections increase once mitigation measures are lifted. In this case, Australia could experience over 15,000 confirmed cases by the end of April 2020. How Australia's government, health authorities and citizens adjust to preventative measures to reduce the risk of transmission as well as the risk of overburdening Australia's health care system is crucial. Our study presents the initial non-pharmaceutical intervention measures undertaken by the Australian health authorities in efforts to mitigate the rate of infection, and their observed and predicted outcomes. Finally, we conclude our study by presenting the observed and expected economic, social, and political disruptions Australians may endure as a result of the initial phase of the pandemic.