Peer Reviewed

Treatment

COVID-19 Roundup: New Treatments, Mask Recommendations, mRNA Vaccine Immunity

Anti-Coagulant Treatment1

Heparin, an anti-coagulant medication, and heparin mimetics may be an effective treatment against COVID-19 variant strains, according to the results of a recent study.

“Epidemiologists believe that persistent low-vaccine coverage in many countries will make it more likely for vaccine-resistant mutations to appear,” the researchers said.2 “Variants of concern have already emerged in South Africa, the US, India and Brazil. In this regard, alternative antiviral strategies are strongly needed to prevent the spread of COVID-19 and to treat people with COVID-19.”

The researchers studied how SARS-CoV-2 spike proteins infect cells to better understand the mutations that have led to variant strains. A glycosaminoglycan binding site was identified, indicating an additional binding site on the receptor-binding domain.

“These findings identify a site in the spike protein that favors heparan sulfate binding that may be particularly pertinent for a better understanding of the recent UK and South African strains,” the researchers concluded. “This will also assist in future targeted therapy programs that could include repurposing clinical heparan sulfate mimetics.”

Monoclonal Antibody Combination Treatment3

A combination of 2 monoclonal antibodies, casirivimab and imdevimab (REGEN-COV), may reduce the risk of death by 20% in patients who are hospitalized with severe COVID-19 but do not have their own antibody immune response, according to the initial results of the Randomized Evaluation of COVID-19 Therapy (RECOVERY) trial.

The trial included 9785 patients who were hospitalized with severe COVID-19 between September 2020 and May 2021. Participants were randomized to receive either standard treatment for COVID-19 alone or in addition to the antibody combination treatment. The antibody combination consisted of 4g of casirivimab and 4g of imdevimab to be delivered intravenously.

The results indicated that the primary outcome of 28-day mortality was significantly decreased by 20% in those who received the antibody combination and were seronegative at baseline.

In addition, the duration of hospital stay was 4 days shorter, the proportion of patients discharged alive by day 28 was higher, and the risk of progressing to the composite endpoint of invasive mechanical ventilation or death was lower for this patient population, in comparison to those who received the usual care

“These results are very exciting. The hope was that by giving a combination of antibodies targeting the SARS-CoV-2 virus we would be able to reduce the worst manifestations of COVID-19,” the researchers concluded. “There was, however, great uncertainty about the value of antiviral therapies in late-stage COVID-19 disease. It is wonderful to learn that even in advanced COVID-19 disease, targeting the virus can reduce mortality in patients who have failed to mount an antibody response of their own.”

These preliminary findings have yet to be peer-reviewed.

WHO’s Mask Recommendation4

The World Health Organization (WHO) continues to recommend mask wearing and social distancing, even in individuals fully vaccinated against COVID-19.

The WHO’s continued recommendation follows concerns of the highly transmissible Delta variant that is now widely circulating within the United States and many parts of the world.

However, the Centers for Disease Control and Prevention has not updated its recommendation regarding the use of masks and continues to recommend mask wearing only in those who are unvaccinated or in certain settings, such as hospitals and public transportation.

Long-Term Immunity From mRNA Vaccines5

Individuals who have been vaccinated against COVID-19 with an mRNA vaccine may have long-term immunity, according to the results of a recent study.

To evaluate the long-term immunity caused by these vaccines, the researchers conducted an observational study measuring the germinal center (GC) reactions of 41 individuals who have been fully vaccinated with the Pfizer-BioNTech COVID-19 vaccine. Blood samples were collected at baseline, weeks 3 (pre-booster shot), 4, 5, 7, and 15 to measure the antigen-specific B cell responses. In addition, fine needle aspirates were used to measure draining axillary lymph nodes in 14 participants.

“Overall, our data demonstrate a remarkable capacity of SARS-CoV-2 mRNA-based vaccines to induce robust and prolonged GC reactions,” the researchers concluded. “The induced GC reaction recruited cross-reactive memory B cells as well as newly engaged clones that target unique epitopes within SARS-CoV-2 S protein. Elicitation of high affinity and durable protective antibody responses iis a hallmark of a successful humoral immune response to vaccination. By inducing robust GC reactions, SARS-CoV-2 mRNA-based vaccines are on track for achieving this outcome.”

 

—Leigh Precopio

 

Reference:

 

  1. Schuurs ZP, Hammond E, Elli S, et al. Evidence of a putative glycosaminoglycan binding site on the glycosylated SARS-CoV-2 spike protein N-terminal domain. Comput Struct Biotec. 2021; 19: 2806-2818. doi: 10.1016/j.csbj.2021.05.002
  2. Anti-coagulant drug could treat COVID-19’s emerging variants. News release. Queensland University of Technology. July 7, 2021. Accessed June 8, 2021. https://www.qut.edu.au/news?id=177875
  3. RECOVERY trial finds Regeneron’s monoclonal antibody combination reduces death for hospitalized COVID-19 patients who have not mounted their own immune response. News release. Nuffield Department of Population Health. June 16, 2021. Accessed July 8, 2021. https://www.recoverytrial.net/news/recovery-trial-finds-regeneron2019s-monoclonal-antibody-combination-reduces-deaths-for-hospitalised-covid-19-patients-who-have-not-mounted-their-own-immune-response-1 
  4. COVID-19 virtual press conference transcript. News release. World Health Organization. June 25, 2021. Accessed June 8, 2021. https://www.who.int/publications/m/item/covid-19-virtual-press-conference-transcript---25-june-2021
  5. Turner JS, O’Halloran J, Kalaidina E, et al. SARS-CoV-2 mRNA vaccines induce persistent human germinal centre responses. Nature. Published online June 28, 2021. Accessed July 8, 2021. doi: 10.1038/s41586-021-03738-2