March 16, 2023

Clinical Reports

Antiviral Therapeutics and Vaccines

  • Clearance of longstanding, immune-deficiency-associated, vaccine-derived polio virus infection following remdesivir therapy for chronic SARS-CoV-2 infection
    The global polio eradication campaign has had remarkable success in reducing wild-type poliovirus infection, largely built upon the live attenuated Sabin oral poliovirus vaccine. Whilst rare, vaccine poliovirus strains may cause infection and subsequently revert to a neurovirulent type, termed vaccine-derived poliovirus (VDPV). Persistent, vaccine derived infection may occur in an immunocompromised host (iVDPV), where it is a recognised complication following receipt of the Sabin vaccine. This has significant implications for the global polio eradication campaign and there is currently no agreed global strategy to manage such patients.Here researchers describe a case of a 50-year-old man with common variable immune deficiency, persistently infected with a neurovirulent vaccine-derived type 2 poliovirus following vaccination in childhood. iVDPV infection had proven resistant to multiple prior attempts at treatment with human breast milk, ribavirin and oral administration of a normal human pooled immunoglobulin product. His iVDPV infection subsequently resolved after 12 days treatment with remdesivir, an adenosine analogue prodrug that is an inhibitor of viral RNA-dependent RNA polymerase, administered as treatment for a prolonged, moderate severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. iVDPV from the patient, isolated prior to treatment, was subsequently demonstrated to be sensitive to remdesivir in vitro. Based on the observations made in this case, and the mechanistic rationale for use with iVDPV, there is strong justification for further clinical studies of remdesivir treatment as a potentially curative intervention in patients with iVDPV infection.

  • Outpatient Treatment of COVID-19 and the Development of Long COVID Over 10 Months: A Multi-Center, Quadruple-Blind, Parallel Group Randomized Phase 3 Trial
    Post-acute sequelae of COVID, termed “Long COVID”, is an emerging chronic illness potentially affecting ~10% of those with COVID-19. Researchers sought to determine if outpatient treatment with metformin, ivermectin, or fluvoxamine could prevent Long COVID. COVID-OUT (NCT04510194) was a decentralized, multi-site trial in the United States testing three medications (metformin, ivermectin, fluvoxamine) using a 2x3 parallel treatment factorial randomized assignment to efficiently share placebo controls. Participants, investigators, care providers, and outcomes assessors were masked to randomized treatment assignment. Inclusion criteria included: age 30 to 85 years with overweight or obesity, symptoms <7 days, enrolled within <=3 days of documented SARS-CoV-2 infection. Long COVID diagnosis from a medical provider was a pre-specified secondary outcome assessed by monthly surveys through 300 days after randomization and confirmed in medical records. Of 1323 randomized trial participants, 1125 consented for long-term follow up, and 95.1% completed >9 months of follow up. The median age was 45 years (IQR, 37 to 54), and 56% were female (7% pregnant). The median BMI was 30 kg/m2 (IQR, 27 to 34). Overall, 8.4% reported a medical provider diagnosed them with Long COVID; cumulative incidence: 6.3% with metformin and 10.6% with matched placebo. The hazard ratio (HR) for metformin preventing Long COVID was 0.58 (95%CI, 0.38 to 0.88; P=0·009) versus placebo. The metformin effect was consistent across subgroups, including viral variants. When metformin was started within <4 days of symptom onset, the HR for Long COVID was 0.37 (95%CI, 0.15 to 0.95).  No statistical difference in Long COVID occurred in those randomized to either ivermectin (HR=0.99; 95%CI, 0.59 to 1.64) or fluvoxamine (HR=1.36; 95%CI, 0.78 to 2.34).A 42% relative decrease and 4.3% absolute decrease in the Long COVID incidence occurred in participants who received early outpatient COVID-19 treatment with metformin compared to exact-matching placebo.

  • Nirmatrelvir and the Risk of Post-Acute Sequelae of COVID-19
    Long Covid – the disease encompassing the post-acute sequelae of SARS-CoV-2 (PASC) —affects millions of people around the world. Prevention of PASC is an urgent public health priority. In this work, we aimed to examine whether treatment with nirmatrelvir in the acute phase of COVID-19 is associated with reduced risk of post-acute sequelae. Researchers used the healthcare databases of the US Department of Veterans Affairs to identify users of the health system who had a SARS-CoV-2 positive test between March 01, 2022 and June 30, 2022, were not hospitalized on the day of the positive test, had at least 1 risk factor for progression to severe COVID-19 illness and survived the first 30 days after SARS-CoV-2 diagnosis. They identify those who were treated with oral nirmatrelvir within 5 days after the positive test (n=9217) and those who received no COVID-19 antiviral or antibody treatment during the acute phase of SARS-CoV-2 infection (control group, n= 47,123). Inverse probability weighted survival models were used to estimate the effect of nirmatrelvir (versus control) on a prespecified panel of 12 post-acute COVID-19 outcomes and reported as hazard ratio (HR) and absolute risk reduction (ARR) in percentage at 90 days. Compared to the control group, treatment with nirmatrelvir was associated with reduced risk of PASC (HR 0.74 95% CI (0.69, 0.81), ARR 2.32 (1.73, 2.91)) including reduced risk of 10 of 12 post-acute sequelae in the cardiovascular system (dysrhythmia and ischemic heart disease), coagulation and hematologic disorders (deep vein thrombosis, and pulmonary embolism), fatigue, liver disease, acute kidney disease, muscle pain, neurocognitive impairment, and shortness of breath. Nirmatrelvir was also associated with reduced risk of post-acute death (HR 0.52 (0.35, 0.77), ARR 0.28 (0.14, 0.41)), and post-acute hospitalization (HR 0.70 (0.61, 0.80), ARR 1.09 (0.72, 1.46)). Nirmatrelvir was associated with reduced risk of PASC in people who were unvaccinated, vaccinated, and boosted, and in people with primary SARS-CoV-2 infection and reinfection. In sum, these results show that in people with SARS-CoV-2 infection who had at least 1 risk factor for progression to severe COVID-19 illness, treatment with nirmatrelvir within 5 days of a positive SARS-CoV-2 test was associated with reduced risk of PASC regardless of vaccination status and history of prior infection. The totality of findings suggests that treatment with nirmatrelvir during the acute phase of COVID-19 reduces the risk of post-acute adverse health outcomes.

  • Optimal Duration of Systemic Corticosteroids in COVID-19 Treatment: A Systematic Review and Meta-analysis
    Corticosteroids confer a survival benefit in individuals hospitalized with coronavirus disease 2019 (COVID-19) who require oxygen. This meta-analysis seeks to determine the duration of corticosteroids needed to optimize this mortality benefit. Electronic databases were searched to 9 March 2022, for studies reporting corticosteroid versus no corticosteroid treatment in hospitalized COVID-19 patients. We estimated the effect of corticosteroids on mortality by random-effects meta-analyses. Subgroup analyses and meta-analyses were conducted to assess the optimal duration of corticosteroid treatment while adjusting for the severity of disease, age, duration of symptoms, and proportion of control group given steroids. Researchers identified 27 eligible studies consisting of 13 404 hospitalized COVID-19 patients. Seven randomized controlled trials and 20 observational studies were included in the meta-analysis of mortality, which suggested a protective association with corticosteroid therapy (risk ratio [RR], 0.71 [95% confidence interval {CI}, .58–.87]). Pooled analysis of 18 studies showed the greatest survival benefit for a treatment duration up to 6 days (RR, 0.54 [95% CI, .39–.74]). Survival benefit was 0.65 (95% CI, .51–.83) up to 7 days, and no additional survival benefit was observed beyond 7 days of treatment (RR, 0.64 [95% CI, .44–.93]). The survival benefit was not confounded by severity of disease, age, duration of symptoms, or proportion of control group given steroids. In this meta-analysis, optimal duration of corticosteroid treatment for hospitalized COVID-19 patients was up to 6 days, with no additional survival benefit with >7 days of treatment.


  • SARS-CoV-2 Exposure in Norway Rats (Rattus norvegicus) from New York City
    Millions of Norway rats (
    Rattus norvegicus) inhabit New York City (NYC), presenting the potential for transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from humans to rats. Researchers evaluated SARS-CoV-2 exposure among 79 rats captured from NYC during the fall of 2021. These results showed that 13 of the 79 rats (16.5%) tested IgG- or IgM-positive, and partial SARS-CoV-2 genomes were recovered from all 4 rats that were qRT-PCR (reverse transcription-quantitative PCR)-positive. Genomic analyses suggest these viruses were associated with genetic lineage B, which was predominant in NYC in the spring of 2020 during the early pandemic period. To further investigate rat susceptibility to SARS-CoV-2 variants, researchers conducted a virus challenge study and showed that Alpha, Delta, and Omicron variants can cause infections in wild-type Sprague Dawley (SD) rats, including high replication levels in the upper and lower respiratory tracts and induction of both innate and adaptive immune responses. Additionally, the Delta variant resulted in the highest infectivity. In summary, these results indicate that rats are susceptible to infection with Alpha, Delta, and Omicron variants, and wild Norway rats in the NYC municipal sewer systems have been exposed to SARS-CoV-2. These findings highlight the need for further monitoring of SARS-CoV-2 in urban rat populations and for evaluating the potential risk of secondary zoonotic transmission from these rat populations back to humans.

  • Exhaled Breath Aerosol Shedding of Highly Transmissible Versus Prior Severe Acute Respiratory Syndrome Coronavirus 2 Variants
    Aerosol inhalation is recognized as the dominant mode of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission. Three highly transmissible lineages evolved during the pandemic. One hypothesis to explain increased transmissibility is that natural selection favors variants with higher rates of viral aerosol shedding. However, the extent of aerosol shedding of successive SARS-CoV-2 variants is unknown. We aimed to measure the infectivity and rate of SARS-CoV-2 shedding into exhaled breath aerosol (EBA) by individuals during the Delta and Omicron waves and compared those rates with those of prior SARS-CoV-2 variants from our previously published work. Individuals with coronavirus disease 2019 (COVID-19) (n = 93; 32 vaccinated and 20 boosted) were recruited to give samples, including 30-minute breath samples into a Gesundheit-II EBA sampler. Samples were quantified for viral RNA using reverse-transcription polymerase chain reaction and cultured for virus. Alpha (n = 4), Delta (n = 3), and Omicron (n = 29) cases shed significantly more viral RNA copies into EBAs than cases infected with ancestral strains and variants not associated with increased transmissibility (n = 57). All Delta and Omicron cases were fully vaccinated and most Omicron cases were boosted. We cultured virus from the EBA of 1 boosted and 3 fully vaccinated cases. Alpha, Delta, and Omicron independently evolved high viral aerosol shedding phenotypes, demonstrating convergent evolution. Vaccinated and boosted cases can shed infectious SARS-CoV-2 via EBA. These findings support a dominant role of infectious aerosols in transmission of SARS-CoV-2. Monitoring aerosol shedding from new variants and emerging pathogens can be an important component of future threat assessments and guide interventions to prevent transmission.

Situation Dashboards


World Health Organization (WHO)

Novel Coronavirus (COVID-19) Situation from World Health Organization (WHO)

Johns Hopkins University (JHU)

Coronavirus COVID-19 Global Cases by the Center for Systems Science and Engineering (CSSE) at JHU

COVID-19 in US and Canada

1Point3Acres Real-Time Coronavirus (COVID-19) Updates in US and Canada with Credible Sources

Genomic Epidemiology COVID-19

Genomic Epidemiology of (COVID-19) Maintained by the Nextstrain team, enabled by data from GISAID.

Sources for COVID-19 Information


World Health Organization (WHO)


Centers for Disease Control, US


International Society for Infectious Diseases


This Week in Virology (TWIV)

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