If I get vaccinated, can I stop with COVID-19 and public health measures?

NO! You will still need to wear a mask, maintain social distance, and wash your hands frequently even after being vaccinated. Everyone entering UHN will still be required to go through screening and wear a mask.

Although vaccination provides protection against symptomatic COVID-19 infection, we are not sure at this point if it prevents the individual from spreading the virus to other people. In fact, we must remain extra vigilant as infection rates are at record highs and wide vaccine rollout will take up to a year. Everyone – vaccinated or not – must continue to mask, practice physical distancing and maintain hand hygiene. Public health recommendations to isolate/quarantine in case of travel or recent exposure remain the same.

If I have had COVID-19 and recovered, do I still need the vaccine?

Yes, people who have had COVID-19 are still encouraged to get the vaccine. We don’t know how long natural immunity from a COVID-19 illness lasts so it is still important to get vaccinated if you have previously had COVID-19. Please speak with your primary care provider to get more information specific to your health status. It is best to get the vaccine to stay protected.

Is there a difference between natural immunity, from getting COVID, and the immunity from getting vaccinated?

We do not yet have sufficient concrete data to understand how long immunity lasts after a COVID infection, or with a vaccine. In other types of infections, we’ve seen that sometimes natural immunity doesn’t last as long as vaccine-induced immunity. But given the scale and urgency of the pandemic, we continue to recommend that people get the vaccine, in case your immunity from natural infection isn’t as long-lasting – and we can extend that immunity period by vaccinating.

What is the COVID-19 vaccine?

The COVID-19 vaccine is indicated for active immunization to prevent symptomatic coronavirus infection (COVID-19). At this moment, we are using the Pfizer and Moderna vaccines at UHN clinics.

How is the vaccine given?

The Pfizer and Moderna vaccines are given as a 2-dose vaccine series. This means you must have two doses of the vaccine. As of March 5, 2021, the Province of Ontario has made the decision to extend the interval between 1st and 2nd doses up to 4 months, or 112 days, for most groups. This has been done to ensure that many more people are vaccinated in the province with the supplies that are received.

Is the vaccine effective against the new reported variants of COVID-19?

There are concerns that some identified mutations can affect antibody response to the virus, rendering the current vaccine less effective. However, it is unlikely that the vaccine will be entirely ineffective against these variants. Thankfully, we have a starting point of over 94% efficacy with the vaccines we’re currently using at UHN (Pfizer and Moderna) in preventing symptomatic infections. Another important piece of good news is that with mRNA technology, new vaccines tailored to mutations can be developed rapidly.

Does delaying the second dose have an impact on vaccine efficacy?

Although clinical trials were done with a shorter interval, several research and regulatory bodies are exploring vaccine efficacy with an extended interval. For further information, please refer to the National Advisory Committee on Immunization (NACI) Recommendations on the use of COVID-19 Vaccine. UHN strongly encourages recipients to still get their second doses when they become available, as even with an extended interval, you would be provided with extra protection against COVID-19 infection.

Can the vaccines give me COVID-19?

No, none of the vaccines approved in Canada can give you COVID-19 or any other illness. Keep in mind, it takes a few weeks for your body to build immunity after getting the vaccination. As a result, it's possible you could become infected with the COVID-19 virus just before or after being vaccinated, but the illness is not a result of the vaccine.

Do the COVID-19 vaccines contain mercury, formaldehyde, aluminum or fetal cells?

No. The COVID-19 vaccines do not contain mercury, formaldehyde, aluminum or fetal cells.

Page last updated: June 21, 2021

What are the potential side effects of the vaccine?

Most people who receive vaccines have minimal or no side effects, although, as with any medicine, adverse reactions can occur. The most common side effects are injection site pain, swelling, redness; headache; stomach and digestive complaints (e.g., nausea, vomiting, diarrhea and/or stomach pain); muscle or joint pain; tiredness; headache and chills/fever.

What do I do if I experience side effects?

Should you develop any of the following symptoms or allergic reactions, seek medical attention right away. Symptoms of an allergic reaction or severe side effects include:

  • Hives
  • Swelling of the face, tongue or throat
  • Difficulty breathing, hoarseness or wheezing
  • High fever (over 40°C or 104°F)
  • Convulsions or seizures

Please report any side effects or severe vaccine reaction to your physician or local health public health unit. If you experience a severe allergic reaction, call 911 or go to the nearest hospital.

You should talk to your primary health provider about known side effects from the vaccine vs. serious adverse reactions.

For TeamUHN and hospital collaborative health care workers:

Any post-vaccine symptoms that are the same as COVID symptoms require employees to follow hospital policies for reporting COVID symptoms. Please check with your organization and follow the appropriate processes. For TeamUHN, find our reporting COVID symptoms process on the Intranet. (Corporate Intranet > COVID-19 Updates > Health and Safety > Health Services COVID-19 Screening for Staff)

Should I go for COVID-19 testing if I had my vaccine in the past few days and have symptoms?

Yes. If you are experiencing any side effects such as fever, headache, chills or fatigue, you should remain off work and go to an assessment centre for testing. Please click here to find a testing centre near you.

Should I delay my COVID-19 vaccine if I am scheduled for surgery?

If you have a vaccine scheduled for less than 7 days before your surgery, you may want to reschedule your vaccine. Up to 15 people out of 100 may get a fever after getting a COVID-19 vaccine. If you have a fever on the day of your surgery, your surgery may be rescheduled.

Wait at least 1 week after your surgery before receiving a vaccine. Having a fever can be a sign of infection after surgery. By waiting 1 week to get the vaccine after surgery, your health care team will be able to determine if the fever is related to an infection and not a vaccine side effect.

Can individuals who are pregnant, breastfeeding or immunocompromised get vaccinated?

We don't have data on these populations since they were excluded from the trials. However, expert groups have judged that for the large majority of people the benefits of the vaccine currently far outweigh any possible risks. As per the latest Ministry of Health guidance, individuals who are pregnant, breastfeeding, or immunosuppressed may be eligible to get vaccinated.

Please note, we cannot provide medical assessments at our vaccination clinics. Questions about personal health must be reviewed with your health care provider before you arrive for your appointment.

Individuals who are pregnant — you will be asked be asked to provide verbal confirmation that you have consulted your health care provider when you arrive at the clinic.

Individuals who are breastfeeding — COVID-19 mRNA vaccines are not live vaccines and, based on their biologic mechanism of action, mRNA vaccines are not thought to be a risk to the breastfeeding infant. You will be asked to provide verbal confirmation that you are aware of the insufficiency of evidence for the use of COVID-19 vaccine in the breastfeeding population.

Individuals with autoimmune conditions, immunodeficiency conditions or those immunosuppressed due to disease/treatment that are receiving stem cell therapy, CAR-T therapy, chemotherapy, immune checkpoint inhibitors, monoclonal antibodies (e.g., rituximab) and other targeted agents (e.g., CD4/6 inhibitors, PARP inhibitors etc.) — you will be asked to provide verbal confirmation that you have consulted your treating provider when you arrive at the clinic.

All other individuals with autoimmune conditions, immunodeficiency conditions or those immunosuppressed due to disease/treatment — you are advised to have a conversation with your health care provider about the risks vs. benefits of taking the vaccine, but are not required to do so.

Click here for additional resources »

Question updated: March 15, 2021

Can I get vaccinated if I have had previous allergic reactions?
  1. If you have had a severe allergic reaction or anaphylaxis to a previous dose of a COVID-19 mRNA vaccine or to any of its components, you should not receive the mRNA COVID-19 vaccine in a general vaccine clinic. An urgent referral to an allergist/immunologist is recommended, and is required to assess the method for possible (re)administration of a COVID-19 vaccine.
  2. If you have had an allergic reaction within 4 hours of receiving a previous dose of an mRNA COVID-19 vaccine or any of components of the mRNA COVID-19 vaccine you should not receive either mRNA COVID-19 vaccine unless you have been evaluated by an allergist-immunologist. The components include polyethylene glycol and, due to potential cross-reactivity, polysorbate.
  3. DOCUMENTATION – If you fall into the above categories, you will be required to present documentation of the discussion with your allergist-immunologist. It must include a vaccination care plan, confirm that appropriate counselling on the safe administration of vaccine was provided, and include the date, the clinician's name, signature and contact information as well as the individual's name and date of birth.

  4. If you have had an allergic reaction within 4 hours and/or anaphylaxis that occurred with a vaccine or injectable medication that does not contain a component or cross-reacting component of the mRNA COVID-19 vaccines, you may be vaccinated, and asked to wait 30 minutes for observation after your receive your vaccine.
  5. If you have a history of significant allergic reactions and/or anaphylaxis to any food, drug, venom, latex, or other allergens not related to the mRNA vaccine, you can be vaccinated with and will be asked to wait 30 minutes for observation after you receive your vaccine.
  6. If you have allergy issues such as allergic rhinitis, asthma or eczema, you can be vaccinated, and will be asked to wait 15-30 minutes after your vaccine for observation.

The medicinal ingredient in both the Pfizer and Moderna Vaccine is mRNA.

Non-Medicinal Ingredients

Pfizer COVID-19 Vaccine

  • ALC-0315 = ((4-hydroxybutyl)azanediyl)bis(hexane-6,1-diyl)bis(2-hexyldecanoate)
  • ALC-0159 = 2-[(polyethylene glycol)-2000]-N,N-ditetradecylacetamide
  • 1,2-Distearoyl-sn-glycero-3-phosphocholine
  • cholesterol
  • dibasic sodium phosphate dihydrate
  • monobasic potassium phosphate
  • potassium chloride
  • sodium chloride
  • sucrose
  • water for injection

View list on Health Canada website

Moderna COVID-19 Vaccine

  • 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC)
  • acetic acid
  • cholesterol
  • lipid SM-102
  • polyethylene glycol (PEG) 2000 DMG
  • sodium acetate
  • sucrose
  • tromethamine
  • tromethamine hydrochloride
  • water for injection

View list on Health Canada website

Question updated: April 13, 2021

What is polyethylene glycol (PEG)? How do I know if I have a PEG allergy?

This compound is commonly used in laxatives, makeup, skin care products, personal lubricants and toothpastes. It is also in cough syrup, and in some food and drinks. PEG is in the COVID-19 vaccines we offer and it has been associated with some allergic reactions from the vaccines. If you are unsure of the ingredients you are allergic to, talk to a health care provider. Please note, we cannot provide medical assessments at our vaccination clinics. Questions about personal health must be reviewed with your health care provider before you arrive for your appointment.

Page last updated: April 13, 2021

The information below applies to health care workers (HCWs) from TeamUHN and the hospital collaborative only. If you're a community-based health care worker, please check the policies for your organization.

Can I go to work if I’m experiencing vaccine side effects?

Mild to moderate side effects are common within the first 48 hours of receiving either dose of the COVID-19 vaccine. If you’re experiencing any side effects that are also considered COVID-19 symptoms, you should self-isolate and contact your organization Occupational Health or Health Services department.

Members from TeamUHN are encouraged to access UHN’s Health Services information tool about vaccine side effects with more details. Please take the time to read the document What to Expect After Receiving the COVID Vaccine, available on UHN’s COVID-19 Preparedness intranet page (Corporate Intranet > COVID-19 Preparedness > Vaccine Information).

Will Occupational Health automatically know I was vaccinated?

No. We are using a provincial system, which means your organization is not automatically updated. Please check with your organization for the current procedure to inform Occupational Health that you have been vaccinated. If you have received the COVID-19 vaccine anywhere, please contact the Health Services/Occupational Health department at the hospital where you work most of your hours to ensure they are notified. You must provide notification after each dose.

Click here for instructions for TeamUHN on how to notify you’ve been vaccinated. (Corporate Intranet > COVID-19 Updates > Vaccine)


The Science Behind Vaccine Dose Intervals: Answering Health Care Worker Questions
Featuring Dr. Brad Wouters, UHN's Executive Vice-President of Science and Research
*Second-dose interval has since been extended to four months, as directed by the Ministry of Health and under guidance from the National Advisory Committee on Immunization (NACI). Otherwise, the content in this video is still accurate.

Page last updated: October 1,​ 2021​

Back to Top