COVID-19 booster shots: Who is eligible for a third dose and how to get it

Since August, select groups have been eligible for a third shot of the COVID-19 vaccine in Ontario, with criteria expanding to include more vulnerable populations over the past several weeks.

The province has said eligibility for booster shots will be expanded to all Ontarians “over time” based on age and risk.

Many have questioned why health officials are not following Israel’s example and broadly recommending a third shot for the general population, just to be safe. The Ministry of Health (MOH) maintains that two shots is a complete vaccine series and provides strong protection against the virus, including the highly transmissible Delta variant.

Only those groups that show a “suboptimal” or “waning” response to the vaccine and are therefore more prone to COVID-19 infection need a third booster shot, as per the MOH’s recommendations.

It is recommended that those who are eligible for a third dose should get an mRNA vaccine — preferably the same brand as their second dose if readily available. Those who received two doses of the Astra Zeneca vaccine should also receive an mRNA shot for their third dose, unless contraindicated or unavailable.

The province recommends that the third shot should be taken at least five months after the second for seniors and two months after the second for other eligible groups. While the National Advisory Committee on Immunization says the minimum gap should be 28 days, provincial health officials say a longer interval is likely to result in a better immune response. However recommendations include allowances for individual risk factors and advise from each person’s treating physician to ensure the gap is right for their specific health condition.

“Some immunocompromised individuals may still be susceptible after the one or two-dose primary series, so their period of susceptibility until receipt of the additional dose will also increase if the interval between doses is increased,” says the MOH.

Who can get a third booster dose?

As of August, booster shots have been available to seniors in congregate settings, those who are moderately to severely immunocompromised and those on specific immunosuppressant medications.

On Nov. 3, eligibility was expanded to include:

• All seniors above 70 years of age
• Those who received two shots of Astra Zeneca or a single shot of the Janssen vaccine
• Any adults in First Nations, Inuit and Metis communities
• Front-line healthcare workers with a short interval between their first two doses.

Starting in early 2022, everyone age 12 and up, who received their second dose at least six to eight months ago will be eligible for a third dose.

Seniors in congregate settings

As per emerging evidence, seniors tend to show a reduced immune response to the COVID-19 vaccines and more rapid waning of antibodies.

Older populations were prioritized for vaccination early in the vaccine rollout, which left more time for waning, should it occur. Further, most seniors were vaccinated within 21 days, and evidence shows a shorter interval results in lower immune response which may also lead to more rapid waning of protection against the virus and variants.

The MOH says that while vaccines have worked in long-term care homes in the three to four months following vaccinations, outbreaks are still occurring, even among fully vaccinated residents.

As such, seniors living in the following congregate settings are eligible for a third booster dose:

• Long-term care homes
• Retirement homes
• Elder care lodges
• Assisted-living facilities
• Chronic care hospitals
• Naturally occurring congregate retirement settings or congregate seniors’ apartment buildings

Public Health Units can also use their discretion, in collaboration with government bodies to determine eligible congregate settings.

Moderately to severely immunocompromised

This group includes people who did not show a strong enough immune response to a complete two-dose vaccine series due to an underlying condition.

• Those receiving “active treatment” for solid tumour or hematologic malignancies. Active treatment includes chemotherapy, targeted therapies and immunotherapy. This includes patients who have completed treatment within the last three months. Those who solely receive hormonal or radiation therapy are not included.
• Solid-organ transplant recipients on immunosuppressive therapy
• Those who received chimeric antigen receptor (CAR)-T-cell therapy or a hematopoietic stem cell transplant, within two years of transplantation or on immunosuppression therapy
• Those with moderate to severe primary immunodeficiency. For example: DiGeorge syndrome and Wiskott-Aldrich syndrome
• Those with stage-3 or advanced untreated HIV infection and those with acquired immunodeficiency syndrome (AIDS)
• Those getting active treatment with these categories of immunosuppressive therapies:
  – Anti-B cell therapies2 (monoclonal antibodies targeting CD19, CD20 and CD22) – including patients who
  have completed treatment within 12 months
  – High-dose systemic corticosteroids
  – Alkylating agents
  – Antimetabolites
  – Tumor-necrosis factor (TNF) inhibitors and other biologic agents that are significantly immunosuppressive
  (See full list below)

List of immunosuppressant medications eligible for third dose

The MOH has provided a list of medications that make an individual eligible for a third dose, but caution that it is not comprehensive. You may still be eligible for a third vaccine dose if your healthcare provider identifies other medications you are on that are significantly immunosuppressive.

A referral from a doctor is not necessary and a prescription or medication bottle can be presented at the vaccine site as proof of eligibility. If the dosing information is not included on the patient’s prescription, confirmation of the
dosage from the patient is acceptable.

The following medications are included on the MOH’s list:

• Steroids:
  – Prednisone (more than 20 mg per day or equivalent for at least 2 weeks)
  – Dexamethasone (Decadron)
  – Methylprednisolone (DepoMedrol, SoluMedrol, Medrol)
• Antimetabolites:
  – Cyclophosphamide (Procytox)
  – Leflunomide (Arava)
  – Methotrexate (Trexall, Metoject, Otrexup, Rasuvo, Rheumatrex)
  – Azathioprine (Imuran)
  – 6-mercaptopurine (Purinethol), mycophenolic acid (Myfortic)
  – Mycophenolate mofetil (Cellcept)
• Calcineurin inhibitors/mTOR kinase inhibitor:
  – Tacrolimus (Prograf, Advagraf, Envarsus PA)
  – Cyclosporine (Neoral, Gengraf, Sandimmune)
  – Sirolimus (Rapamune)
• JAK (Janus kinase) inhibitors:
  – Baricitinib (Olumiant)
  – Tofacitinib (Xeljanz)
  – Upadacitinib (Rinvoq)

• Anti-TNF (tumor necrosis factor):
  – Adalimumab (Humira, Amgevita, Hadlima, Hulio, Hyrimoz, Idacio)
  – Golimumab (Simponi)
  – Certolizumab pegol (Cimzia)
  – Etanercept (Enbrel, Brenzys, Erelzi)
  – Infliximab (Remicade, Avsola, Inflectra, Remsima, Renflexis)

• Anti-inflammatory:
  – Sulfasalazine (Salazopyrin, Azulfidine)
  – 5-Aminosalicylic Acid (ASA)/mesalamine (Pentasa)

• IL-1 RA (interleukin-1 receptor antagonist):
  – Anakinra (Kineret)
  – Canakinumab (Ilaris)

• Anti-CD20:
  – Rituximab (Rituxan, Ruxience, Riximyo, Truxima, Riabni)
  – Ocrelizumab (Ocrevus)

• Anti- IL6:
  – Tocilizumab (Actemra)
  – Sarilumab (Kevzara)

• Anti-IL12/IL23:
  – Ustekinumab (Stelara)
• Anti-IL17:
  – Secukinumab (Cosentyx)
  – Ixekizumab (Taltz)

• Anti-ILI7R:
  – Brodalumab (Siliq)

• Anti-BLyS:
  – Belimumab (Benlysta)
• Anti-IL23:
  Guselkumab (Tremfya)
  Risankizumab (Skyrizi)

• Anti-integrin:
  Vedolizumab (Entyvio)

• Selective T-cell costimulation blocker:
  – Abatacept (Orencia)
  – Fingolimod (Gilenya)

• S1PR (sphingosine 1-phosphate receptor) agonist:
  – Siponimod (Mayzent)
  – Ozanimod (Zeposia)

• Phosphodiesterase inhibitors:
  – Apremilast (Otezla)

How to get your third dose

If you fall into any of the above eligible groups, a third dose can be arranged via the same avenues as your first and second dose: through your family doctor or specialist or at a mass vaccination clinic, hospital clinic or select pharmacies.
Seniors living in congregate settings can receive their dose at their long-term care home or seniors’ residence.

Primary care provider or specialist

If your primary care provider or specialist for your condition is participating in COVID-19 vaccination, you can book an appointment and arrange to get the vaccine at their clinic.

Mass vaccination clinic, hospital clinic or pharmacy

In order to get your third dose at a mass vaccination clinic, hospital clinic or pharmacy you will need a referral letter from your doctor or specialist.

The letter must include your full name and address and your OHIP number. It should also confirm that you meet the eligibility criteria for a third dose.

An appointment must be booked through the province’s booking portal.

If you are eligible based on medication listed above, a prescription or medication bottle can be presented at the vaccine site as proof of eligibility and a referral letter is not mandatory.