February 8, 2021

Clinical Reports

  • Full-dose blood thinners decreased need for life support and improved outcome in hospitalized COVID-19 patients
    In large clinical trial conducted worldwide, full dose anti-coagulation (blood thinner) treatments given to moderately ill patients hospitalized for COVID-19 reduced the requirement of vital organ support—such as the need for ventilation. A trend in possible reduction of mortality was also observed and is being further studied. With large numbers of COVID-19 patients requiring hospitalization, these outcomes could also help reduce the overload on intensive care units around the world. Early in the pandemic, physicians around the world observed increased rates of blood clots and inflammation among COVID-19 patients which affected multiple organs and led to complications such as lung failure, heart attack and stroke. Whether providing increased doses of blood thinners routinely administered to hospitalized patients would be safe and effective was unknown at that time. Three clinical trial platforms spanning five continents in more than 300 hospitals have been working together to test whether there is a greater benefit of full doses of heparin (blood thinners) to treat moderately ill hospitalized adults with COVID-19 compared to the lower heparin dose typically administered to prevent blood clots in hospitalized patients. Moderately ill patients are those not in intensive care and who did not receive organ support such as mechanical ventilation at trial enrollment. Based on the interim results of more than 1,000 moderately ill patients admitted to hospital, findings showed that full doses of blood thinners, in addition to being safe, were superior to the doses normally given to prevent blood clots in hospitalized patients—with regard to the primary endpoint which is the need for ventilation or other organ supportive interventions. The trial investigators are now working as fast as possible to make the full results of the study available so clinicians can make informed decisions about treating their COVID-19 patients.

Antiviral Therapeutics and Vaccines

  • Increased Resistance of SARS-CoV-2 Variants B.1.351 and B.1.1.7 to Antibody Neutralization
    Recent emergence of new SARS-CoV-2 variants B.1.1.7 in the UK and B.1.351 in South Africa is of concern because of their purported ease of transmission and extensive mutations in the spike protein. B.1.1.7 is refractory to neutralization by most mAbs to the N-terminal domain (NTD) of spike and relatively resistant to a number of mAbs to the receptor-binding domain (RBD). It is modestly more resistant to convalescent plasma (~3 fold) and vaccinee sera (~2 fold). Findings on B.1.351 are more worrisome in that this variant is not only refractory to neutralization by most NTD mAbs but also by multiple individual mAbs to the receptor-binding motif on RBD, largely due to an E484K mutation, although some mAb combinations retain activity. Moreover, B.1.351 is markedly more resistant to neutralization by convalescent plasma (~11-33 fold) and vaccinee sera (~6.5-8.6 fold). B.1.351 and emergent variants with similar spike mutations present new challenges for mAb therapy and threaten the protective efficacy of current vaccines.

  • Safety and efficacy of an rAd26 and rAd5 vector-based heterologous prime-boost COVID-19 vaccine: an interim analysis of a randomised controlled phase 3 trial in Russia
    Authors report preliminary results on the efficacy and safety of Gam-COVID-Vac from the interim analysis of a phase 3 trial of A heterologous recombinant adenovirus (rAd)-based vaccine, Gam-COVID-Vac (Sputnik V). Between Sept 7 and Nov 24, 2020, 21 977 adults were randomly assigned to the vaccine group (n=16 501) or the placebo group (n=5476). 19 866 received two doses of vaccine or placebo and were included in the primary outcome analysis. From 21 days after the first dose of vaccine (the day of dose 2), 16 (0·1%) of 14 964 participants in the vaccine group and 62 (1·3%) of 4902 in the placebo group were confirmed to have COVID-19; vaccine efficacy was 91·6% (95% CI 85·6–95·2). Most reported adverse events were grade 1 (7485 [94·0%] of 7966 total events). 45 (0·3%) of 16 427 participants in the vaccine group and 23 (0·4%) of 5435 participants in the placebo group had serious adverse events; none were considered associated with vaccination, with confirmation from the independent data monitoring committee. Four deaths were reported during the study (three [<0·1%] of 16 427 participants in the vaccine group and one [<0·1%] of 5435 participants in the placebo group), none of which were considered related to the vaccine. This interim analysis of the phase 3 trial of Gam-COVID-Vac showed 91·6% efficacy against COVID-19 and was well tolerated in a large cohort.

  • Robust spike antibody responses and increased reactogenicity in seropositive individuals after a single dose of SARS-CoV-2 mRNA vaccine
    An important question is arising as COVID-19 vaccines are getting rolled out: Should individuals who already had a SARS-CoV-2 infection receive one or two shots of the currently authorized mRNA vaccines. In this short report, authors show that the antibody response to the first vaccine dose in individuals with pre-existing immunity is equal to or even exceeds the titers found in naïve individuals after the second dose. Reactogenicity is significantly higher in individuals who have been infected with SARS-CoV-2 in the past. Changing the policy to give these individuals only one dose of vaccine would not negatively impact on their antibody titers, spare them from unnecessary pain and free up many urgently needed vaccine doses.

  • Single Dose Vaccination in Healthcare Workers Previously Infected with SARS-CoV-2
    Coronavirus disease 2019 (COVID-19) vaccine shortages have led some experts and countries to consider untested dosing regimens. Authors studied antibody responses to a single dose of the Pfizer-BioNTech or Moderna vaccines in healthcare workers (HCW) with laboratory-confirmed COVID-19 infection and compared to them to antibody responses of HCW who were IgG negative to SARS-CoV-2 spike protein. HCW with prior COVID-19 showed clear secondary antibody responses to vaccination with IgG spike binding titers rapidly increasing by 7 days and peaking by days 10 and 14 post-vaccination. At all time points tested, HCW with prior COVID-19 infection showed statistically significant higher antibody titers of binding and functional antibody compared to HCW without prior COVID-19 infection (p<.0001for each of the time points tested). In times of vaccine shortage, and until correlates of protection are identified, these findings preliminarily suggest the following strategy as more evidence-based: a) a single dose of vaccine for patients already having had laboratory-confirmed COVID-19; and b) patients who have had laboratory-confirmed COVID-19 can be placed lower on the vaccination priority list.

  • Interim Clinical Considerations for Use of mRNA COVID-19 Vaccines Currently Authorized in the United States
    These CDC vaccination guidelines include updated considerations on Updated recommendations on intervals between the first and second dose. Persons should not be scheduled to receive the second dose earlier than recommended (i.e., 3 weeks [Pfizer-BioNTech] or 1 month [Moderna]). However, second doses administered within a grace period of 4 days earlier than the recommended date for the second dose are still considered valid. Doses inadvertently administered earlier than the grace period should not be repeated. T
    he second dose should be administered as close to the recommended interval as possible. However, if it is not feasible to adhere to the recommended interval, the second dose of Pfizer-BioNTech and Moderna COVID-19 vaccines may be scheduled for administration up to 6 weeks (42 days) after the first dose. There are currently limited data on efficacy of mRNA COVID-19 vaccines administered beyond this window. If the second dose is administered beyond these intervals, there is no need to restart the series.

  • Single Dose Administration, And The Influence Of The Timing Of The Booster Dose On Immunogenicity and Efficacy Of ChAdOx1 nCoV-19 (AZD1222) Vaccine
    Authors present data from phase III efficacy trials of ChAdOx1 nCoV-19 in the United Kingdom and Brazil, and phase I/II clinical trials in the UK and South Africa, against symptomatic disease caused by SARS-CoV-2. 17,177 baseline seronegative trial participants were eligible for inclusion in the efficacy analysis, 8948 in the UK, 6753 in Brazil and 1476 in South Africa, with 619 documented NAAT +ve infections of which 332 met the primary endpoint of symptomatic infection >14 days post dose 2. The primary analysis of overall vaccine efficacy >14 days after the second dose including LD/SD and SD/SD groups, based on the prespecified criteria was 66.7% (57.4%,  74.0%). There were no hospitalizations in the ChAdOx1 nCoV-19 group after the initial 21 day exclusion period, and 15 in the control group. Vaccine efficacy after a single standard dose of vaccine from day 22 to day 90 post vaccination was 76% (59%, 86%), and modelled analysis indicated that protection did not wane during this initial 3 month period. Similarly, antibody levels were maintained during this period with minimal waning by day 90 day (GMR 0.66, 95% CI 0.59, 0.74). In the SD/SD group, after the second dose, efficacy was higher with a longer prime-boost interval: VE 82.4% 95%CI 62.7%, 91.7% at 12+ weeks, compared with VE 54.9%, 95%CI 32.7%, 69.7% at <6 weeks. These observations are supported by immunogenicity data which showed binding antibody responses more than 2-fold higher after an interval of 12 or more weeks compared with and interval of less than 6 weeks GMR 2.19 (2.12, 2.26) in those who were 18-55 years of age. ChAdOx1 nCoV-19 vaccination programs aimed at vaccinating a large proportion of the population with a single dose, with a second dose given after a 3 month period is an effective strategy for reducing disease, and may be the optimal for rollout of a pandemic vaccine when supplies are limited in the short term.

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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