Self-limited Polymyalgia Rheumatica-like Syndrome Following mRNA-1273 SARS-CoV-2 Vaccination

Polymyalgia rheumatica (PMR) is an inflammatory rheumatic disease characterized by stiffness and aching mainly in the shoulders, neck and hip girdles. The underlying pathogenesis of PMR involves myeloid lineage activation with a high expression of pattern recognition receptors. In addition, vaccination against severe acute respiratory syndrome coronavirus 2 with mRNA-1273 functions as both an immunogen and intrinsic adjuvant. It leads to the activation of innate immunity, resulting in antibody production. We herein report the first case of PMR-like syndrome seven days after mRNA-1273 vaccination. Reassuringly, the symptoms, such as pain of the neck, shoulder girdle and pelvic girdle, as well as elevated inflammatory markers were resolved within a month without glucocorticoid or immunosuppressant administration.     

Development of DNA Vaccine Candidate against SARS-CoV-2

Despite the existence of various types of vaccines and the involvement of the world’s leading pharmaceutical companies, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remains the most challenging health threat in this century. Along with the increased transmissibility, new strains continue to emerge leading to the need for more vaccines that would elicit protectiveness and safety against the new strains of the virus. Nucleic acid vaccines seem to be the most effective approach in case of a sudden outbreak of infection or the emergence of a new strain as it requires less time than any conventional vaccine development. Hence, in the current study, a DNA vaccine encoding the trimeric prefusion-stabilized ectodomain (S1+S2) of SARS-CoV-2 S-protein was designed by introducing six additional prolines mutation, termed HexaPro. The three-dose regimen of designed DNA vaccine immunization in mice demonstrated the generation of protective antibodies.     

Case Study of Two Post Vaccination SARS-CoV-2 Infections with P1 Variants in CoronaVac Vaccinees in Brazil

The rapid development of efficacious and safe vaccines against coronavirus disease 2019 (COVID-19) has been instrumental in mitigating the transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Moreover, the emergence of SARS-CoV-2 variants raised concerns on the efficacy of these vaccines. Herein, we report two cases of breakthrough infections with the P1 variant in patients vaccinated with CoronaVac, which is one of the two vaccines authorized for emergency use in the Brazilian immunization program. Our observations suggest that the vaccine reduced the severity of the disease and highlight the potential risk of illness following vaccination and subsequent infection with the P1 variant as well as for continued efforts to prevent and diagnose infection in vaccinated persons.     

Miller Fisher syndrome after COVID-19 vaccination: Case report and review of literature

Rationale:Miller Fisher syndrome (MFS) is a rare variant of Guillain-Barre syndrome, classically diagnosed based on the clinical triad of ataxia, areflexia, and ophthalmoplegia. MFS is usually preceded by viral infections and febrile illness; however, only a few cases have been reported after vaccinations.Patient concerns:A 53-year-old hypertensive male presented with a 2-day history of progressive ascending paralysis of the lower limbs along with diplopia and ataxia, 8 days after the first dose of the Sinovac–Coronavac coronavirus disease 2019 (COVID-19) vaccination, with no prior history of any predisposing infections or triggers.Diagnoses:Physical examination showed moderate motor and sensory loss with areflexia in the lower limbs bilaterally. Routine blood investigations and radiological investigations were unremarkable. Cerebrospinal fluid analysis showed albuminocytologic dissociation and nerve conduction studies revealed prolonged latencies with reduced conduction velocities. The diagnosis of MFS was established based on the findings of physical examination, cerebrospinal fluid analysis, and nerve conduction studies.Interventions:A management plan was devised based on intravenous immunoglobulins, pregabalin, and physiotherapy. However, due to certain socioeconomic factors, the patient was managed conservatively with regular physiotherapy sessions.Outcomes:Follow-up after 6 weeks showed remarkable improvement, with complete resolution of symptoms 10 weeks after the discharge.Lessons:This case suggests that MFS is a rare adverse effect after COVID-19 vaccination and additional research is required to substantiate a temporal association. Further studies are needed to understand the pathophysiology behind such complications to enhance the safety of COVID-19 vaccinations in the future.     

Refractory Longitudinally Extensive Transverse Myelitis after Severe Acute Respiratory Syndrome Coronavirus 2 Vaccination in a Japanese Man

Vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been developed and administered worldwide. There have been reports of neurological adverse events following immunization (AEFIs). We herein report a case of refractory longitudinally extensive transverse myelitis in a 75-year-old Japanese man following the first dose of the BNT162b2 vaccine. The patient developed total sensory loss below the umbilicus and complete paralysis in both legs. Although he was treated with steroid therapy and plasma exchange, his recovery was limited, and severe sequelae remained. Further studies, including large epidemiological studies, are required to understand the association between SARS-CoV-2 vaccines and neurological AEFI.     

Venous Thrombosis within 30 Days after Vaccination against SARS-CoV-2 in a Multinational Venous Thromboembolism Registry

Background: Venous thromboembolism (VTE)—including deep vein thrombosis, pulmonary embolism, and cerebral venous sinus thrombosis (CVST)—may occur early after vaccination against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We sought to describe the site, clinical characteristics, and outcomes of VTE after vaccination against SARS-CoV-2. Methods: In a prospective study using the Registro Informatizado de Enfermedad TromboEmbólica (RIETE) platform, patients with VTE 4–30 days after vaccination against SARS-CoV-2 (1 February 2021 through 30 April 2021) were included. VTE patients recruited from the same centers into RIETE in the same months in 2018–2019 were selected as the reference group. All-cause mortality and major bleeding were the main study outcomes. Results: As of 30 April 2020, 102 patients with post-vaccination VTEs had been identified (28 after adenovirus-based vaccination [ChAdOx1 nCov-19; AstraZeneca] and 74 after mRNA-based vaccination [mRNA-1273; Moderna, and BNT162b2; Pfizer]). Compared with 911 historical controls, patients with VTE after adenovirus-based vaccination more frequently had CVST (10.7% vs. 0.4%, p < 0.001) or thrombosis at multiple sites (17.9% vs. 1.3%, p < 0.001), more frequently had thrombocytopenia (40.7% vs. 14.7%, p < 0.001), and had higher 14-day mortality (14.3% vs. 0.7%; odds ratio [OR]: 25.1; 95% confidence interval [CI]: 6.7–94.9) and major bleeding rates (10.3% vs. 1.0%, OR: 12.03, 95% CI: 3.07–47.13). The site of thrombosis, accompanying thrombocytopenia, and 14-day mortality rates were not significantly different for patients with VTE after mRNA-based vaccination, compared with historical controls. Conclusions: Compared with historical controls, VTE after adenovirus-based vaccination against SARS-CoV-2 is accompanied by thrombocytopenia, occurs in unusual sites, and is associated with worse clinical outcomes.     

The durability of natural infection and vaccine-induced immunity against future infection by SARS-CoV-2

The durability of vaccine-mediated immunity to SARS-CoV-2, the durations to breakthrough infection, and the optimal timings of booster vaccination are crucial knowledge for pandemic response. Here, we applied comparative evolutionary analyses to estimate the durability of immunity and the likelihood of breakthrough infections over time following vaccination by BNT162b2 (Pfizer-BioNTech), mRNA-1273 (Moderna), ChAdOx1 (Oxford-AstraZeneca), and Ad26.COV2.S (Johnson & Johnson/Janssen). We evaluated anti-Spike (S) immunoglobulin G (IgG) antibody levels elicited by each vaccine relative to natural infection. We estimated typical trajectories of waning and corresponding infection probabilities, providing the distribution of times to breakthrough infection for each vaccine under endemic conditions. Peak antibody levels elicited by messenger RNA (mRNA) vaccines mRNA-1273 and BNT1262b2 exceeded that of natural infection and are expected to typically yield more durable protection against breakthrough infections (median 29.6 mo; 5 to 95% quantiles 10.9 mo to 7.9 y) than natural infection (median 21.5 mo; 5 to 95% quantiles 3.5 mo to 7.1 y). Relative to mRNA-1273 and BNT1262b2, viral vector vaccines ChAdOx1 and Ad26.COV2.S exhibit similar peak anti-S IgG antibody responses to that from natural infection and are projected to yield lower, shorter-term protection against breakthrough infection (median 22.4 mo and 5 to 95% quantiles 4.3 mo to 7.2 y; and median 20.5 mo and 5 to 95% quantiles 2.6 mo to 7.0 y; respectively). These results leverage the tools from evolutionary biology to provide a quantitative basis for otherwise unknown parameters that are fundamental to public health policy decision-making.

The unprecedented development of efficacious vaccines against SARS-CoV-2 has represented a triumph in the global effort to control the ongoing COVID-19 pandemic. Vaccines have been shown to provide short-term protection from major adverse health outcomes of hospitalization and death (1–4). However, protection against breakthrough infection wanes (5), and breakthroughs have been extensively documented (6, 7). In response, the Food and Drug Administration advisory committee has recommended a booster of the Pfizer-BioNTech and Moderna vaccines at least 5 mo after completion of the primary series to people ≥12 and ≥18 y of age, respectively (8). A booster dose of the Johnson & Johnson/Janssen vaccine has been authorized on a faster timescale—as early as 2 mo after the single dose to individuals 18 y of age and older (8). Nevertheless, the optimal timing of boosting remains challenging to assess. Consequently, rigorous prediction of the durability of immunity conferred by vaccination against the SARS-CoV-2 virus is essential to personal and public health decision-making, having major implications regarding policy decisions about COVID-19 vaccination around the world (9, 10).Short-term longitudinal studies of SARS-CoV-2-neutralizing antibodies in vaccinated individuals (11–13) can provide information crucial to our understanding of the durability of vaccine-mediated immunity. Peak antibody responses following vaccination versus natural responses have also been quantified (14), facilitating analytical comparison of initial immune responses. For endemic viruses, longitudinal data on reinfection can provide reinfection probabilities associated with antibody level. However, longitudinal data on SARS-CoV-2 reinfection are not available during the short term associated with pandemic spread. Nevertheless, longitudinal reinfection data for a diversity of coronaviruses have been collected (15–20). SARS-CoV-2 reinfection probabilities have been obtained from them by phylogenetic analysis, using continuous ancestral and descendent state estimation (21). These estimates, produced before reinfection was commonplace, proved accurate (predicting an 18% probability of reinfection at ∼270 d [ref. 21] that was validated by a subsequent empirical finding of 18% reinfection by 275 to 300 d after primary infection [ref. 22] and, likewise, predicting a 34% probability of reinfection at ∼450 d after primary infection [ref. 21] that was validated by a subsequent empirical finding of 34% breakthrough infection 420 to 480 d after primary vaccination [ref. 23]). Similar analyses pairing antibody response and rates of waning for each vaccine with infection probabilities can enable quantification of the durability of vaccine-mediated immunity against breakthrough infections. The aim of this study is to leverage data on antibody response to each vaccine and corresponding probabilities of infection to estimate the durability of vaccine-mediated immunity against breakthrough SARS-CoV-2 infection for four well-studied vaccines: mRNA-1273, BNT162b2, ChAdOx1, and Ad26.COV2.S.     

IgA-Dominant Infection-Associated Glomerulonephritis Following SARS-CoV-2 Infection

The renal involvement of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been reported. The etiology of kidney injury appears to be tubular, mainly due to the expression of angiotensin-converting enzyme 2, the key joint receptor for SARS-CoV-2; however, cases with glomerular implication have also been documented. The multifactorial origin of this renal involvement could include virus-mediated injury, cytokine storm, angiotensin II pathway activation, complement dysregulation, hyper-coagulation, and microangiopathy. We present the renal histological findings from a patient who developed acute kidney injury and de novo nephrotic syndrome, highly suggestive of acute IgA-dominant infection-associated glomerulonephritis (IgA-DIAGN) after SARS-CoV-2 infection, as evidenced by the presence of this virus detected in the renal tissue of the patient via immunohistochemistry assay. In summary, we document the first case of IgA-DIAGN associated to SARS-CoV-2. Thus, SARS-CoV-2 S may act as a super antigen driving the development of multisystem inflammatory syndrome as well as cytokine storm in patients affected by COVID-19, reaching the glomerulus and leading to the development of this novel IgA-DIAGN.     

Autoimmune liver diseases and SARS-CoV-2

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), causing coronavirus disease 2019 (COVID-19), can trigger autoimmunity in genetically predisposed individuals through hyperstimulation of immune response and molecular mimicry. Here we summarise the current knowledge about auto-immune liver diseases (AILDs) and SARS-CoV-2, focusing on: (1) The risk of SARS-CoV-2 infection and the course of COVID-19 in patients affected by AILDs; (2) the role of SARS-CoV-2 in inducing liver damage and triggering AILDs; and (3) the ability of vaccines against SARS-CoV-2 to induce autoimmune responses in the liver. Data derived from the literature suggest that patients with AILDs do not carry an increased risk of SARS-Cov-2 infection but may develop a more severe course of COVID-19 if on treatment with steroids or thiopurine. Although SARS-CoV-2 infection can lead to the development of several autoimmune diseases, few reports correlate it to the appearance of de novo manifestation of immune-mediated liver diseases such as autoimmune hepatitis (AIH), primary biliary cholangitis (PBC) or AIH/PBC overlap syndrome. Different case series of an AIH-like syndrome with a good prognosis after SARS-CoV-2 vaccination have been described. Although the causal link between SARS-CoV-2 vaccines and AIH cannot be definitively established, these reports suggest that this association could be more than coincidental.     

Effect of Previous COVID-19 Vaccination on Humoral Immunity 3 Months after SARS-CoV-2 Omicron Infection and Booster Effect of a Fourth COVID-19 Vaccination 2 Months after SARS-CoV-2 Omicron Infection

In this study, we aimed to determine the effect of COVID-19 vaccination on 3-month immune response and durability after natural infection by the Omicron variant and to assess the immune response to a fourth dose of COVID-19 vaccination in patients with prior natural infection with the Omicron variant. Overall, 86 patients aged ≥60 years with different vaccination histories and 39 health care workers (HCWs) vaccinated thrice before Omicron infection were enrolled. The sVNT50 titer was significantly lower in patients with incomplete vaccination before SARS-CoV-2 infection with the S clade (p < 0.001), Delta variant (p < 0.001), or Omicron variant (p = 0.003) than in those vaccinated thrice. The sVNT results against the Omicron variant did not differ significantly in patients aged ≥60 years (p = 0.49) and HCWs (p = 0.17), regardless of the recipient receiving the fourth dose 2 months after COVID-19. Incomplete COVID-19 vaccination before Omicron infection for individuals aged ≥60 years conferred limited protection against homologous and heterologous virus strains, whereas two or three doses of the vaccine provided cross-variant humoral immunity against Omicron infection for at least 3 months. However, a fourth dose 2 months after Omicron infection did not enhance immunity against the homologous strain. A future strategy using the bivalent Omicron-containing booster vaccine with appropriate timing will be crucial.     

New-Onset and Relapsed Membranous Nephropathy post SARS-CoV-2 and COVID-19 Vaccination

Since the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreak and COVID-19 vaccination, new-onset and relapsed clinical cases of membranous nephropathy (MN) have been reported. However, their clinical characteristics and pathogenesis remained unclear. In this article, we collected five cases of MN associated with SARS-CoV-2 infection and 37 related to COVID-19 vaccination. Of these five cases, four (4/5, 80%) had acute kidney injury (AKI) at disease onset. Phospholipase A2 receptor (PLA2R) in kidney tissue was negative in three (3/5, 60%) patients, and no deposition of virus particles was measured among all patients. Conventional immunosuppressive drugs could induce disease remission. The underlying pathogenesis included the subepithelial deposition of viral antigens and aberrant immune response. New-onset and relapsed MN after COVID-19 vaccination generally occurred within two weeks after the second dose of vaccine. Almost 27% of patients (10/37) suffered from AKI. In total, 11 of 14 cases showed positive for PLA2R, and 20 of 26 (76.9%) presented with an elevated serum phospholipase A2 receptor antibody (PLA2R-Ab), in which 8 cases exceeded 50 RU/mL. Conventional immunosuppressive medications combined with rituximab were found more beneficial to disease remission for relapsed patients. In contrast, new-onset patients responded to conservative treatment. Overall, most patients (24/37, 64.9%) had a favorable prognosis. Cross immunity and enhanced immune response might contribute to explaining the mechanisms of MN post COVID-19 vaccination.     

Miller Fisher Syndrome with Central Involvement: Successful Treatment with Plasmapheresis

Miller Fisher syndrome is characterized by external ophthalmoplegia, ataxia, and areflexia. Most researchers favor a peripheral origin while others suggest a brainstem inflammatory lesion or a combination of central and peripheral demyelination. We report 2 cases of Miller Fisher syndrome with the typical triad of ataxia, areflexia, and ophthalmoplegia. Strong clinical evidence of central involvement included initial drowsiness, bilateral Babinski sign, and quadriparesis. Evoked potential studies showed prolongation of central conduction time. Plasmapheresis was performed to relieve respiratory failure in Patient 1 and to shorten the duration of nasogastric tube feeding due to severe bulbar palsy in Patient 2. Significant improvement of electrophysiologic parameters was recorded after plasmapheresis. Abnormal evoked potentials, together with clinical evidence of central nervous system abnormalities, support the hypothesis that there is a combination of peripheral and central involvement in Miller Fisher syndrome in our patients. Plasmapheresis is highly effective in relieving the profound neurological deficits of this atypical syndrome.     

Clusters of SARS-CoV-2 Lineage B.1.1.7 Infection after Vaccination with Adenovirus-Vectored and Inactivated Vaccines

A SARS-CoV-2 B.1.1.7 variant of concern (VOC) has been associated with increased transmissibility, hospitalization, and mortality. This study aimed to explore the factors associated with B.1.1.7 VOC infection in the context of vaccination. On March 2021, we detected SARS-CoV-2 RNA in nasopharyngeal samples from 14 of 22 individuals vaccinated with a single-dose of ChAdOx1 (outbreak A, n = 26), and 22 of 42 of individuals with two doses of the CoronaVac vaccine (outbreak B, n = 52) for breakthrough infection rates for ChAdOx1 of 63.6% and 52.4% for CoronaVac. The outbreaks were caused by two independent clusters of the B.1.1.7 VOC. The serum of PCR-positive symptomatic SARS-CoV-2-infected individuals had ~1.8–3.4-fold more neutralizing capacity against B.1.1.7 compared to the serum of asymptomatic individuals. These data based on exploratory analysis suggest that the B.1.1.7 variant can infect individuals partially immunized with a single dose of an adenovirus-vectored vaccine or fully immunized with two doses of an inactivated vaccine, although the vaccines were able to reduce the risk of severe disease and death caused by this VOC, even in the elderly.     

Successful Treatment of Immune Thrombocytopenic Purpura with Intracranial Hemorrhaging and Duodenal Bleeding Following SARS-CoV-2 Vaccination

Several vaccines have been developed for coronavirus disease 2019 - caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) - in record time. A few cases of immune thrombocytopenic purpura (ITP) following SARS-CoV-2 vaccination have been reported. We herein report a 90-year-old man who received the Pfizer-BioNTech SARS-CoV-2 vaccine (BNT162b2) and developed severe thrombocytopenia with intracranial hemorrhaging and duodenal bleeding, consistent with vaccine-related ITP. He was successfully treated with intravenous immunoglobulin, prednisolone, and eltrombopag and discharged without cytopenia. Vaccine-related ITP should be suspected in patients presenting with abnormal bleeding or purpura after vaccination.     

Antibody Response to SARS-CoV-2 Infection and Vaccination in COVID-19-naïve and Experienced Individuals

Understanding the magnitude of responses to vaccination during the ongoing SARS-CoV-2 pandemic is essential for ultimate mitigation of the disease. Here, we describe a cohort of 102 subjects (70 COVID-19-naïve, 32 COVID-19-experienced) who received two doses of one of the mRNA vaccines (BNT162b2 (Pfizer–BioNTech) and mRNA-1273 (Moderna)). We document that a single exposure to antigen via infection or vaccination induces a variable antibody response which is affected by age, gender, race, and co-morbidities. In response to a second antigen dose, both COVID-19-naïve and experienced subjects exhibited elevated levels of anti-spike and SARS-CoV-2 neutralizing activity; however, COVID-19-experienced individuals achieved higher antibody levels and neutralization activity as a group. The COVID-19-experienced subjects exhibited no significant increase in antibody or neutralization titer in response to the second vaccine dose (i.e., third antigen exposure). Finally, we found that COVID-19-naïve individuals who received the Moderna vaccine exhibited a more robust boost response to the second vaccine dose (p = 0.004) as compared to the response to Pfizer–BioNTech. Ongoing studies with this cohort will continue to contribute to our understanding of the range and durability of responses to SARS-CoV-2 mRNA vaccines.     

Bepridil is potent against SARS-CoV-2 in vitro

Guided by a computational docking analysis, about 30 Food and Drug Administration/European Medicines Agency (FDA/EMA)-approved small-molecule medicines were characterized on their inhibition of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) main protease (M^pro). Of these small molecules tested, six displayed a concentration that inhibits response by 50% (IC₅₀) value below 100 μM in inhibiting M^pro, and, importantly, three, that is, pimozide, ebastine, and bepridil, are basic molecules that potentiate dual functions by both raising endosomal pH to interfere with SARS-CoV-2 entry into the human cell host and inhibiting M^pro in infected cells. A live virus-based modified microneutralization assay revealed that bepridil possesses significant anti−SARS-CoV-2 activity in both Vero E6 and A459/ACE2 cells in a dose-dependent manner with low micromolar effective concentration, 50% (EC₅₀) values. Therefore, the current study urges serious considerations of using bepridil in COVID-19 clinical tests.

The current worldwide impact of the COVID-19 pandemic has been so profound that it is often compared to that of the 1918 influenza pandemic (1, 2). As of February 4, 2021, the total global COVID-19 cases had surpassed 100 million, among which more than 2 million had succumbed to death (3). Important political figures who have been diagnosed COVID-19 positive include the US president Donald Trump and the UK prime minister Boris Johnson. A modeling study has predicted that this pandemic will continue to affect everyday life, and the circumstances may require societies to follow social distancing until 2022 (4). Finding timely treatment options is of tremendous importance to alleviate catastrophic damages of COVID-19. However, the short time window that is required to contain the disease is extremely challenging for a conventional drug discovery process that requires typically many years to finalize a drug and therefore might not achieve its goal before the pandemic ceases. In January 2020, we did a comparative biochemical analysis between severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that has caused COVID-19, and SARS-CoV-1 that led to an epidemic in China in 2003, and proposed that remdesivir was a viable choice for the treatment of COVID-19 (5). We were excited to see that remdesivir was finally approved for emergency use in the United States and for use in Japan for people with severe symptoms. With only one medicine in stock that provides very limited benefits to COVID-19 patients (6), the virus may easily evade it, leaving us once again with no medicine to use. Given the rapid spread and the high fatality rate of COVID-19, finding alternative medicines is imperative. Drug repurposing stands out as an attractive option in the current situation. If an approved drug can be identified to treat COVID-19, it can quickly proceed to clinical trials and be manufactured at a large scale using its existing good manufacturing practice (GMP) lines. Previously, encouraging results were obtained from repurposing small-molecule medicines, including teicoplanin, ivermectin, itraconazole, and nitazoxanide (7–10). These antimicrobial agents showed antiviral activity against Ebola, Chikungunya, enterovirus, and influenza viruses, respectively (11). However, a common drawback of a repurposed drug is its low efficacy level. One way to circumvent this problem is to combine multiple existing medicines to accrue a synergistic effect. To be able to discover such combinations, breaking down the druggable targets of SARS-CoV-2 to identify drugs that do not cross-act on each other’s targets is a promising strategy. For example, a recent study showed that triple combination of interferon β-1b, lopinavir−ritonavir, and ribavirin was safe and superior to lopinavir−ritonavir alone for treating COVID-19 patients (12).In our January paper (5), we recommended four SARS-CoV-2 essential proteins, including Spike, RNA-dependent RNA polymerase, the main protease (M^pro), and papain-like protease, as drug targets for the development of anti−COVID-19 therapeutics. Among these four proteins, M^pro that was previously called 3C-like protease provides the most facile opportunity for drug repurposing, owing to the ease of its biochemical assays. M^pro is a cysteine protease that processes itself and then cleaves a number of nonstructural viral proteins from two very large polypeptide translates that are made from the viral genomic RNA in the human cell host (13). Its relatively large active site pocket and a highly nucleophilic, catalytic cysteine residue make it likely to be inhibited by a host of existing and investigational drugs. Previous work has disclosed some existing drugs that inhibit M^pro (14). However, complete characterization of existing drugs on the inhibition of M^pro is not yet available. Since the release of the first M^pro crystal structure, many computational studies have been carried out to screen existing drugs in their inhibition of M^pro, and many potent leads have been proposed (15–18). However, most of these lead drugs are yet to be confirmed experimentally. To investigate whether some existing drugs can potently inhibit M^pro, we have docked a group of selected Food and Drug Administration/European Medicines Agency (FDA/EMA)-approved small-molecule medicines to the active site of M^pro and selected about 30 hit drugs to characterize their inhibition on M^pro experimentally. Our results revealed that a number of FDA/EMA-approved small-molecule medicines have high potency in inhibiting M^pro, and bepridil inhibits cytopathogenic effect (CPE) induced by the SARS-CoV-2 virus in Vero E6 and A549/ACE2 cells with low micromolar effective concentration, 50% (EC₅₀) values. Therefore, the current study encourages further preclinical testing of bepridil in animal models, paving the way to its clinical use against COVID-19.     

Influence of the Delta Variant and Vaccination on the SARS-CoV-2 Viral Load

Studies comparing SARS-CoV-2 nasopharyngeal (NP) viral load (VL) according to virus variant and host vaccination status have yielded inconsistent results. We conducted a single center prospective study between July and September 2021 at the drive-through testing center of the Toulouse University Hospital. We compared the NP VL of 3775 patients infected by the Delta (n = 3637) and Alpha (n = 138) variants, respectively. Patient’s symptoms and vaccination status (2619 unvaccinated, 636 one dose and 520 two doses) were recorded. SARS-CoV-2 RNA testing and variant screening were assessed by using Thermo Fisher^® TaqPath™ COVID-19 and ID solutions^® ID™ SARS-CoV-2/VOC evolution Pentaplex assays. Delta SARS-CoV-2 infections were associated with higher VL than Alpha (coef = 0.68; p ≤ 0.01) independently of patient’s vaccination status, symptoms, age and sex. This difference was higher for patients diagnosed late after symptom onset (coef = 0.88; p = 0.01) than for those diagnosed early (coef = 0.43; p = 0.03). Infections in vaccinated patients were associated with lower VL (coef = −0.18; p ≤ 0.01) independently of virus variant, symptom, age and sex. Our results suggest that Delta infections could lead to higher VL and for a longer period compared to Alpha infections. By effectively reducing the NP VL, vaccination could allow for limiting viral spread, even with the Delta variant.