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Canadian Public Health Association

Long acting monoclonal antibodies

Information for Canadians on COVID-19 pre-exposure prophylaxis (prevention) with monoclonal antibodies

Updated: 12 May 2022, 15:00 (ET)

Monoclonal antibodies have been around for more than 30 years; with approximately 100 monoclonal antibodies designated as new medicines since 1985. They have been approved and used to treat many diseases such as severe asthma, rheumatoid arthritis, Crohn’s disease, multiple sclerosis, infectious diseases, and some types of cancer. Monoclonal antibodies may play an important role in preventing COVID-19 in people who do not have healthy immune systems and can be engineered to be long-acting.

Currently there is only one pre-exposure long acting monoclonal antibody (LAAB) available in Canada for the prevention of COVID-19: Evusheld (tixagevimab and cilgavimab).

No drug, including Evusheld, is a substitute for vaccination. Vaccination remains the most important tool in preventing serious illness from COVID-19 infection. Both the Public Health Agency of Canada and Health Canada continue to strongly recommend up-to-date vaccination for all eligible Canadians.

The information contained on this page is not intended to substitute for the advice of a health professional, and you are advised always to consult your health professional for specific information on personal health matters.

About Evusheld

On 14 April 2022, Health Canada authorized Evusheld (tixagevimab and cilgavimab) for the prevention of COVID-19. The drug is approved for use in adults and children (12 years of age and older, weighing at least 40 kg) who are not currently infected with COVID-19 and have not had recent known contact with someone infected with COVID-19, and:

  • who are immune compromised and unlikely to mount an adequate immune response to COVID‐19 vaccination; or,
  • for whom COVID-19 vaccination is not recommended.

Patients should talk to their healthcare provider to determine if Evusheld is appropriate for them. Evusheld is not currently authorized to treat COVID-19 infection, nor is it authorized to prevent infection in people who have been exposed to the virus.

Provincial/Territorial Guidance: Who is eligible and how to access?

Educational Resources for Eligible Patients

FREQUENTLY ASKED QUESTIONS

Who may need additional protection against COVID-19?

While vaccines are helping people around the world, not everyone who receives a vaccine is able to mount a sufficient response to protect them from COVID-19.1-5 These vulnerable populations may need additional protection.

About 2% of the global population may remain vulnerable to COVID-19 because of an inadequate response to a COVID-19 vaccine.6,7 More than 40% of those hospitalized with breakthrough infections after vaccination are immune-compromised.8-10

Dozens of studies show that substantially fewer immune-compromised individuals generate an antibody response to COVID-19 vaccines compared with those who are not immune-compromised.11 In many of these studies, the proportion of immune-compromised people who generated a protective immune response was between zero to 60%.6

In addition to those who are immune-compromised, there are vulnerable populations that may require additional protection against COVID-19, including:

  • Those who it may not be possible to vaccinate, for example those with allergies or other intolerance to the vaccine.12
  • Those at increased risk of COVID-19 infection based on their work or living situation.13

Who is considered immune-compromised?

Examples of immune-compromised individuals may include, but are not limited to, people:1-5,14

  • With blood cancers
  • Undergoing active chemotherapy or radiotherapy
  • With a transplant
  • Undergoing dialysis
  • Taking immunosuppressants (e.g., medicines for non-Hodgkin’s lymphoma, lupus, multiple sclerosis, rheumatoid arthritis)
  • With primary immune deficiency

What are the options available for the immune-compromised community?

There are a number of prevention and treatment options available for the immune-compromised community, including vaccines, antivirals, and monoclonal antibodies.

Vaccines:15

  • Vaccines are agents that start an immune response.
  • Vaccines aim to help the body prevent infection and the immune response develops a few weeks after vaccination.
  • Vaccines are expected to provide long-term protection.

Antivirals:16,17

  • Antivirals prevent virus replication and lower viral load.
  • Antivirals help the body fight and prevent viral infection. Depending on the specific treatment, they take effect quickly.
  • The effects of antivirals last as long as they are taken.

Monoclonal Antibodies:

  • A monoclonal antibody is a copy of a natural antibody aimed at neutralizing the virus.4
  • Monoclonal antibodies have the potential to protect against infection or treat an illness and work almost immediately.18-20
  • The duration of the effects of monoclonal antibodies may vary, but generally they have the potential to last many months.15,20
  • Monoclonal antibodies may support in preventing COVID-19 in people who do not have healthy immune systems, and can be long-acting.18,21-24

What is a monoclonal antibody and what are monoclonal antibodies used to treat?

Antibodies are an important part of the body’s defence system to destroy disease-causing organisms and are often made from pathogen-specific immune cells of people who have recovered from an infection.25,26 Monoclonal antibodies (mAbs) are made in a laboratory to mimic or improve the body’s natural immune response.25

Monoclonal antibodies target the spike protein in COVID-19, which bonds and fuses the virus to the host cell membrane. In targeting this spike, the antibody can neutralize the effects of the virus by affecting its capacity to infect healthy cells.26

Monoclonal antibodies (mAbs) have been around for more than 30 years; with approximately 100 mAbs designated as new medicines since 1985. They have been approved and used to treat many diseases such as severe asthma, rheumatoid arthritis, Crohn’s disease, multiple sclerosis, infectious diseases, and some types of cancer.27

Monoclonal antibodies may play an important role in preventing COVID-19 in people who do not have healthy immune systems and can be engineered to be long-acting.18,21-23

What is the role of monoclonal antibodies in protecting the immune-compromised from COVID-19?

Monoclonal antibodies have the potential to help the millions of people globally, including thousands of Canadians, who may be unable to mount an adequate response from a vaccine due to an underlying health condition or medication they take that compromises or suppresses their immune system.1-5

This population includes people with blood cancers or other cancers being treated with chemotherapy, patients on dialysis, those taking medications after an organ transplant or who are taking immunosuppressive drugs for conditions, including multiple sclerosis and rheumatoid arthritis.1-5

How do monoclonal antibodies differ from vaccines?

Monoclonal antibody therapies have the potential to complement vaccines to protect against disease, but differ in the way they work, what they do, how quickly they take effect and how long they last.

  • While vaccines start an immune response using a weakened pathogen or particle, monoclonal antibodies mimic the body’s natural antibodies to neutralize a virus.15,25
  • Vaccines aim to help the body prevent infection while monoclonal antibodies have both the potential to protect against infection and/or treat an illness.15,19,27
  • Monoclonal antibodies begin working almost immediately and, with modifications, have the potential to last many months, while vaccines develop an immune response a few weeks after vaccination and are expected to provide long-term protection.19,20

What is acquired immunity?

Acquired immunity is immunity you develop over your lifetime.28 It can come from:

  • A vaccine
  • Exposure to an infection or disease
  • Another person’s antibodies (infection-fighting immune cells)

When pathogens (germs) are introduced into your body from a vaccine or a disease, your body learns to target those germs in the future by making new antibodies. Antibodies from another person can also help your body fight an infection – but this immunity is temporary.

Acquired immunity is different than innate immunity, which you’re born with. Your innate immune system doesn’t fight specific germs. Instead, it protects against all germs, like bacteria and viruses by trying to keep them from entering your body. Your innate immune system includes:

  • Your cough reflex
  • Stomach acid
  • Your skin and its enzymes
  • Mucus

What is the difference between active and passive immunity?

Active immunity and passive immunity are the two types of acquired immunity.

Active immunity is the most common type. It develops in response to an infection or vaccination.20

  • Natural active immunity comes from antibodies made after exposure to an infection.
  • Artificial active immunity comes from antibodies made after getting a vaccination.

Passive immunity is after you receive antibodies from someone or somewhere else and is naturally short-lived.20

  • Natural passive immunity comes from antibodies transmitted from mother to baby (e.g., via mother’s milk).
  • Artificial passive immunity comes from antibodies acquired from an immune serum medication.

REFERENCES

  1. Centers for Disease Control and Prevention. Altered immunocompetence. General Best Practice Guideline for Immunization: Best Practices Guidance of the Advisory Committee on Immunization Practices.
  2. Boyarsky BJ, et al. Immunogenicity of a single dose of SARS-CoV-2 messenger RNA vaccine in solid organ transplant recipients. JAMA 2021;325(17):1784-1786.
  3. Rabinowich L, et al. Low immunogenicity to SARS-CoV-2 vaccination among liver transplant recipientsJ Hepatology 2021.
  4. Deepak P, et al. Glucocorticoids and B cell depleting agents substantially impair immunogenicity of mRNA vaccines to SARS-CoV-2. medRxiv. [Preprint] 2021. PMID: 33851176; PMCID: PMC8043473.
  5. Simon D, et al. SARS-CoV-2 vaccination responses in untreated, conventionally treated and anticytokine-treated patients with immune- mediated inflammatory diseases. Ann Rheum Dis 2021.
  6. Oliver, S MD. Data and clinical considerations for additional doses in immunocompromised people. ACIP Meeting July 22, 2021.
  7. AstraZeneca Data on File.
  8. Harpaz et al. Prevalence of immunosuppression among US adults, 2013. JAMA 2016 Dec 20;316(23):2547-48.
  9. Tenforde MW, et al. Effectiveness of SARS-CoV-2 mRNA vaccines for preventing Covid-19 hospitalizations in the United States. medRxiv. [Preprint] 2021.
  10. Brosh-Nissimov T, et al. BNT162b2 vaccine breakthrough: clinical characteristics of 152 fully vaccinated hospitalized COVID-19 patients in Israel. Clin Microbiol Infect 2021.
  11. AstraZeneca Data on File.
  12. Centers for Disease Control and Prevention. COVID-19 vaccines for people with allergies. 2021.
  13. Centers for Disease Control and Prevention. Risk factors of exposure to COVID-19: racial and ethnic health disparities. 2020.
  14. Grupper A, Sharon N, Finn T, Cohen R, Israel M, Agbaria A, Rechavi Y, Schwartz IF, Schwartz D, Lellouch Y, Shashar M. Humoral response to the Pfizer BNT162b2 vaccine in patients undergoing maintenance hemodialysis. Clin J Am Soc Nephrol 2021 Apr 6.
  15. Centers for Disease Control and Prevention. Understanding How Vaccines Work. CDC.gov; 2018.
  16. Cleveland Clinic. Antivirals. [Online]. 2021 November 5.
  17. Government of Canada. Coronavirus disease (COVID-19): Prevention and Risks. [Online] 2022 January 1.
  18. Domachowske JB, et al. Safety, tolerability and pharmacokinetics of MEDI8897, an extended half-life single-dose respiratory syncytial virus prefusion F-targeting monoclonal antibody administered as a single dose to healthy preterm infants. Pediatr Infect Dis J 2018; 37(9): 886-892.
  19. Loo Y-M, et al. AZD7442 demonstrates prophylactic and therapeutic efficacy in non-human primates and extended half-life in humans. medRxiv. Cold Spring Harbor Laboratory Press; 2021 [preprint]
  20. CDC Centers for Disease Control and Prevention (CDC). Immunity types. [Online]. 2017 May 10.
  21. AstraZeneca news release. AZD7442 PROVENT Phase III prophylaxis trial met primary endpoint in preventing COVID-19.
  22. Robbie GJ, et al. A novel investigational Fc-modified humanized monoclonal antibody, motavizumab-YTE, has an extended half-life in healthy adults. Antimicrob Agents Chemother 2013;57(12):6147-53.
  23. Griffin MP, et al. Safety, tolerability, and pharmacokinetics of MEDI8897, the respiratory syncytial virus prefusion F-targeting monoclonal antibody with an extended half-life, in healthy adults. Antimicrob Agents Chemother 2017;61(3):e01714-16.
  24. Yu XQ, et al. Safety, tolerability, and pharmacokinetics of MEDI4893, an investigational, extended-half-life, anti-staphylococcus aureus alpha- toxin human monoclonal antibody, in healthy adults. Antimicrob Agents Chemother 2016;61(1):e01020-16.
  25. Lloyd E, Gandhi T, Petty L. Monoclonal antibodies for COVID-19. JAMA. 2021; 325(10):1015. doi:10.1001/jama.2021.1225.
  26. Zost, S.J., et al. Potently neutralizing and protective human antibodies against SARS-CoV-2. Nature 2020. 584:443-49.
  27. Lu RM, et al. Development of therapeutic antibodies for the treatment of diseases. J Biomed Sci 2020;27,1.
  28. Healthline. What you need to know about acquired immunity. [Online].