Diagnosis and Treatment of COVID-19

Welcome back to the discussion about COVID19. In this second of three videos, we will cover the diagnosis and treatment of COVID-19. The WHO published its first protocol to diagnose SARS-CoV-2 on January, 13 2020. It was a nucleic acid-based test that detects the SARS-CoV-2 genetic material, which is made of RNA. Nucleic acid based tests are good because they can detect low levels of virus. They are very sensitive and specific tests. In other words, they are good at correctly identifying true infections while also correctly ruling out non-infections. On the downside, nucleic acid based tests can take hours to days to yield results and are relatively expensive.

Later, in May 2020, the Food and Drug Administration, or FDA, approved the COVID-19 antigen test, which detects viral antigens, or proteins. The benefits of antigen testing is that results are available within minutes. However, they can miss infections with low levels of virus. Antibody, or serologic, testing, detects antibodies produced by our immune system against the virus. These tests are not useful in detecting active COVID-19 infections, but if positive, can indicate prior infection or vaccination. Samples for testing can be taken from different sites. The virus replicates (makes an exact copy of itself) in cells along our respiratory tract. Specimens for testing can be taken from those locations. These locations can include the nasal passageways which

would include: the anterior nares or mid-turbinates, the nasopharynx, or oropharynx. Who should get tested? People who have signs and symptoms, such as fever, cough, myalgias (meaning muscle pain), gastrointestinal symptoms, and anosmia (remember that’s loss of smell), of COVID-19 should get tested. People who are asymptomatic but have had close contact with someone with a confirmed or suspected case of COVID-19 in the prior 14 days should also be tested. Additionally, people who are asymptomatic but at high risk of becoming infected should be tested.

These include employees and residents at congregate living facilities, hospitalized patients at locations where prevalence is high, and patients prior to surgical procedures or In addition, anyone who wants to know their COVID-19 status for a myriad of reasons including, for example, fit-for-flying internationally and going to work in lieu of vaccination. If diagnosed with COVID-19, management depends on disease severity. In mild disease, the disease is generally self-limiting and does not require hospitalization. This is not true for moderate to severe disease. Can you recall the signs or symptoms that distinguish severe disease from mild disease? If you said dyspnea or difficulty breathing, shortness of breath, or hypoxia or low oxygen, you would be correct! People with severe disease may need to be hospitalized.

If hospitalized, patients are carefully monitored for signs or symptoms of disease progression. Conservative treatment is centered around symptom management. If patients become hypoxic or have low oxygen, they may require oxygen therapy. This can be through non-invasive means, such as via the nose or mouth, but if severe enough, may require the use of a ventilator. A ventilator requires a breathing tube that goes down to the lungs to help a person breathe. The use of other therapies for COVID-19 continues to evolve. The recommendations continue to change as medical experts learn more from clinical trials. I’ll review the rationale behind a few of these therapies. I’ll first discuss antibody-based therapy, but this requires a quick review of immunology.

I want you to pause for a moment, and consider this question. What cell type produces antibodies?

If you said, B cell, you’re correct! Now, do you remember how antibodies protect our bodies against viral infections? [pause then advance] They do so by neutralization, or blockage of the site or sites on pathogens that they use to enter their target cell. As with other viral infections, antibodies are important in immunity to COVID-19. Convalescent plasma is plasma donated by individuals who have recovered from COVID-19. Convalescent plasma contains antibodies the donating individual’s immune system made against SARS-CoV- 2. When transfused into someone who is infected, these antibodies can help protect against severe COVID-19. Monoclonal antibodies work similarly, but are produced in a lab dish. As the name suggests, monoclonal antibodies are a single clone of antibody that binds to a single antigen.

For the treatment of COVID-19, antibody clones that can efficiently bind to viral spike protein are the best at preventing virus entry into cells. Because antibody-therapy works by preventing virus entry into cells, it is best used earlier in the disease course. Antiviral therapies target different stages of the virus life cycle, from viral entry into the cell to viral replication inside the cell. Remdesivir is an antiviral therapy that interferes with viral replication. Remdesivir was approved for the treatment of COVID-19 by the Food and Drug Administration, or FDA, on October 22, 2020. As of August 2021, it is the only FDA approved antiviral for the treatment of COVID-19. Remdesivir is given intravenously (through a vein).

The FDA approval is limited to administration to a patient in a hospital or congregate care setting. There are many other ongoing clinical trials on the use of antivirals in COVID-19. Finally, I will discuss immunomodulators. If you recall from the previous video, patients with severe COVID-19 have an inappropriate immune response marked by excess inflammation. One class of medications used to treat severe COVID-19 is the immunomodulators, which work to dampen inflammation. Examples of medications that have anti-inflammatory properties are corticosteroids, like dexamethasone, and the cytokine, interleukin-6 receptor blocker. I hope this review of current treatments is useful to you. In the next video I will See you soon.