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The Nurse Practitioner Blog

A forum for discussion on recent news and developments in healthcare and the NP field.

Monday, October 12, 2020

The promise of antibodies and vaccines for COVID-19

Both the political and medical worlds have been abuzz with the experimental antibody cocktail that President Donald Trump received to combat his coronavirus disease 2019 (COVID-19) infection earlier this month.

So, is the cocktail ready to treat society at large?  

In trials, the antibody therapy, REGN-COV2—produced by the biotechnology firm Regeneron—led to quick reduction in levels of the virus and reduced symptoms in infected non-hospitalized patients with mild to moderate disease. The trial is also separately studying the effectiveness of REGN-COV2 for the treatment of hospitalized patients and prevention of infection in those exposed to the virus.

The antibody cocktail includes two proteins that mimic the antibodies that are produced by the body’s own immune system during an infection; these lab-created antibodies are expected to bind to the virus and prevent it from entering cells, thus inhibiting infection. In the trial, the greatest positive effects of therapy were seen in patients who had not mounted their own immune response, which means the treatment could be an effective substitute for a naturally occurring immune response.

“This potentially would be helpful for patients that wouldn’t respond—either they have a problem with their immune system, something called primary deficiency, or cancer, transplant patients that may not be necessarily candidates for a regular vaccine—this potentially would offer some benefit in protecting them,” Gary Kleiner, MD, an allergy & immunology specialist at the University of Miami Miller School of Medicine, said at an expert panel discussion with trial site doctors and the American Medical Association. “We’re performing a preventive trial there with this combination used for household contacts in the hope of decreasing transmission in these subjects.”

Regeneron's monoclonal antibody cocktail is just one of many clinical trials currently underway with regard to prevention and treatment of COVID-19. A majority of the trials, understandably, are focused on producing an effective vaccine.

A new vaccine for coronavirus disease 2019 (COVID-19) just entered clinical trials at the end of September.

The vaccine is a recombinant vector that uses a nonvirulent human adenovirus to express the SARS-CoV-2 spike protein in cells. “This particular vaccine is using Adenovirus 26, it’s a type of respiratory virus that we commonly see, but it is genetically modified to have the coronavirus part of the genome in it, and it’s a non-replicating virus,” Dushyahtha Jayaweera, MD, explained at the panel. Jayaweera is an infectious disease specialist and professor of clinical medicine at the University of Miami, and is working on the vaccine trial. “So, once you inject it, it gets into the cell and introduces this genetic material and then the immune system will recognize it and produce antibodies.”

The spike protein, also called the S protein, is an ideal target for COVID-19 immunotherapy, since antibodies directed against it play a key role in countering coronavirus infection, and have been shown to be effective at inhibiting virus entry into host cells. By eliciting a polyclonal antibody response, the S protein effectively neutralizes SARS-CoV-2 entry into cells. It showed complete or near-complete protection against the virus in rhesus macaques.

The spike protein is a good molecular target for vaccines because the virus attaches to human cells through it; the protein binds to a protein on the human cell surface, following which, the viral membrane fuses with the human cell membrane, allowing entry of the viral genome into the host cell.

The fourth large-scale COVID-19 vaccine trial in the US, it will evaluate if the vaccine can prevent symptomatic COVID-19 after a single dose regimen. The trial is being funded by Janssen Pharmaceutical Companies, of Johnson & Johnson, which developed the vaccine, the National Institute of Allergy and Infectious Diseases (NIAID), and the Biomedical Advanced Research and Development Authority (BARDA) —part of the U.S. Department of Health and Human Services.

The Janssen vaccine has shown promise in early-stage testing. If it can demonstrate effective protection after a single dose, it can be especially useful in controlling the pandemic. It can also be rapidly produced.

“One of the advantages of this vaccine is that their platform can have rapid operationalization and create one billion vaccine doses over the next year,” Jayaweera said. “So that’s one of the advantages, provided the study shows that it works.”

Treatments like Regeneron’s antibody cocktail and Janssen’s vaccine give us hope at a time when COVID-19 cases continue to rise.

As Susan Bailey, MD, President of the American Medical Association noted at the panel, “There are over a hundred vaccines that are in the preclinical stage of investigation. There are about a half a dozen vaccines that are in phase 3 trials, three of which are going on in the U.S., three in other parts of the world, and others that are in various stages in the pipeline. So, there's an incredible amount of activity that’s going on in this area, which I think is just absolutely amazing.”