Antiviral treatments for COVID-19 – implementation issues
The virus called SARS-CoV-2 causes disease called COVID-19. In this issue of TreatmentUpdate, we provide summaries of research on both authorized and experimental treatments for mild-to-moderate COVID-19.
Treatment for SARS-CoV-2 infection is relatively new and it will take time for doctors, nurses and health systems to develop expertise in deploying treatment.
Antiviral drugs are not a substitute for vaccines
Note that COVID-19 treatments are not a substitute for COVID-19 vaccinations. These vaccines, particularly ones made by Moderna and Pfizer-BioNTech, are generally safe, highly effective at preventing severe illness and hospitalization, and provide longer protection than antiviral drugs. Vaccines are also much cheaper.
Cleaning and protection
People with early-stage COVID-19 tend to have high levels of SARS-CoV-2. As a result, hospitals and clinics that treat people in the early stages of COVID-19 need to take precautions to protect their staff and other patients from the risk of infection. This requires disinfecting surfaces, wearing protective equipment and, when necessary, filtering the air or getting fresh air into a treatment room. Furthermore, sufficient time between patient visits is needed so that rooms where patients have been treated can be cleaned. All of these precautions can add to necessary delays in treating patients.
There is another important factor to consider: The past 18 months of the pandemic have left healthcare personnel exhausted and some clinics may be short-staffed. This can result in additional delays in the administration of treatment and may impact the number of people with COVID-19 that can be treated in one day. Thus, there are many issues that can affect the ability of hospitals and clinics to deploy antibody therapies such as sotrovimab and Regen-CoV (both antibodies are detailed later in this issue of TreatmentUpdate).
Antiviral treatments for SARS-CoV-2
This issue of TreatmentUpdate covers two types of treatment for COVID-19: antibody infusions and oral antiviral drugs. At the time this issue was drafted, the only treatment that was currently available in Canada was antibodies that attack SARS-CoV-2. These are available in liquid formulation and are meant to be given as intravenous infusions. If the antibodies were swallowed, the digestive system would degrade them.
There are also oral formulations of antiviral drugs. Currently some oral treatments are in clinical trials while others are under review by regulatory authorities. These treatments – whether antibody infusions or antiviral drugs in pill form – are most effective when taken very early in the course of COVID-19.
Treatments for COVID-19 are expensive and scarce relative to the number of people who test positive for SARS-CoV-2. Most intravenous antivirals cost about US$2,100 for one dose (only one dose is needed). The experimental oral treatment, molnupiravir, is projected to cost about US$700 per course of treatment.
However, Canada’s federal government has negotiated with pharmaceutical companies, signed contracts and engaged in bulk purchasing (thousands of doses) of antibody treatments for COVID-19. These must be administered intravenously. They have been distributed to Canada’s provinces and territories and can be used at no cost to patients.
A path to treatment
People who may have been exposed to COVID-19 need swift, low-barrier access to SARS-CoV-2 testing. If they test positive, patients need to be assessed by an experienced healthcare professional to find out if they are at high risk for developing severe COVID-19. If they are at such risk, patients require a clear and simple path forward so that they can access treatment. People who could be prioritized for treatment might include some members of vulnerable populations (outlined below) whose ability to contain SARS-CoV-2 are weakened despite having received COVID-19 vaccines.
A closer look at some potentially vulnerable populations
The large clinical trials that took place last year with many COVID-19 vaccines did not include sufficient numbers of people with compromised immune systems to draw firm conclusions about vaccine effectiveness in these populations. As a result, teams of researchers around the world have had to do vaccine studies in such people.
Populations that could have some degree of immune compromise include the following:
- people with cancer
- people with chronic inflammatory conditions that require treatment, including arthritis, Crohn’s and colitis, multiple sclerosis and psoriasis
- people with HIV
- elderly people in long-term care homes
- people with transplanted organs
Important to note
Not every person from a vulnerable population will have a poor response to COVID-19 vaccination and therefore be at high risk for developing COVID-19 should they become infected with SARS-CoV-2. For instance, emerging data from Canada, Israel and the UK suggest that two doses of COVID-19 vaccines work just as well in many HIV-positive people who are on successful HIV treatment (their viral load is suppressed) as they do in the average HIV-negative person. And many people who have the other conditions previously listed may have an adequate response to at least two COVID-19 vaccinations.
Doctors are trying to understand which members of vulnerable populations who become infected with SARS-CoV-2 will require treatment for this virus.
Implementation
Ideally, implementation of pilot projects to assess how antibody therapies can be administered across Canada would be helpful. This would allow more doctors to better understand which patients and groups might benefit from treatments for COVID-19. It could also help uncover barriers that can prevent people from accessing treatment for early COVID-19.
In high-income countries, despite the widespread availability of potent and generally safe COVID-19 vaccines, the pandemic continues, though at a much-reduced pace compared to the time before vaccines. Many people take precautions to minimize their potential exposure to SARS-CoV-2. Despite such measures and vaccinations, a minority of people may still become infected with SARS-CoV-2, and a very small proportion of these people —such as some who have the issues previously mentioned — may go on to develop serious complications of COVID-19.
Physicians can assess the potential risk of worsening COVID-19 in people who are diagnosed with early SARS-CoV-2 infection. They can then help guide members of vulnerable populations to receive treatment for early COVID-19. Such treatment has several potential benefits, as follows:
- it reduces the spread of SARS-CoV-2 to other people
- it reduces the risk of severe illness requiring hospitalization
- it reduces the risk of death
—Sean R. Hosein
REFERENCES:
- GlaxoSmithKline. Sotrovimab for injection. Product monograph. 14 September 2021.
- Hoffmann-La Roche. Casirivimab and imdevimab for injection. Product monograph. 9 June 2021.
- Sherwin C. “Good news,” says doctor: Some Quebec COVID-19 patients to soon have access to monoclonal antibody treatment. CTV News. 14 October 2021. Available at: https://montreal.ctvnews.ca/good-news-says-doctor-some-quebec-covid-19-patients-to-soon-have-access-to-monoclonal-antibody-treatment-1.5622809
- Rubin R. Monoclonal antibodies for COVID-19 preexposure prophylaxis can’t come fast enough for some people. JAMA. 2021; in press.
- Rahav G, Lustig Y, Lavee J, et al. BNT162b2 mRNA COVID-19 vaccination in immunocompromised patients: A prospective cohort study. EClinicalMedicine. 2021 Nov;41:101158.
- Brumme ZL, Mwimanzi F, Lapointe HR, et al. Humoral immune responses to COVID-19 vaccination in people living with HIV receiving suppressive antiretroviral therapy. medRxiv [Preprint]. 2021 Oct 15:2021.
- Frater J, Ewer KJ, Ogbe A, et al. Safety and immunogenicity of the ChAdOx1 nCoV-19 (AZD1222) vaccine against SARS-CoV-2 in HIV infection: a single-arm sub-study of a phase 2/3 clinical trial. Lancet HIV. 2021 Aug;8(8):e474-e485.