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COVID-19 Vaccine After Care: Pfizer-BioNTech and Moderna Vaccines

Please remain in the clinic for 15 minutes after your vaccine.

Serious side effects after receiving the COVID-19 vaccine are rare. If you develop any signs and symptoms that could be an allergic reaction soon after vaccination, seek medical attention right away from clinic staff, or call 911 if you have left.

Symptoms of an allergic reaction include:

  • Hives (bumps on the skin that are often very itchy).
  • Swelling of the face, tongue or throat.
  • Difficulty breathing.

Your health care provider will inform your local public health unit of any serious side effects after receiving your immunization. Reports of adverse reactions to vaccines are sent to Public Health Ontario and the Public Health Agency of Canada.

If you have any concerns or questions after your immunization, please call your local public health unit.

What should I expect in the next few days?

  • COVID-19 vaccines, like other vaccines and medications, may cause side effects, although not everyone will experience these. Most side effects are minor and don’t last long.
  • Common side effects after receiving the COVID-19 vaccine include pain at injection site, redness, swelling, tiredness, headache, muscle pain, chills, joint pain, and fever.
  • A cool damp cloth or covered ice pack placed where the vaccine was given may help with soreness. Medication, such as acetaminophen or ibuprofen, may be given for pain or fever as needed.

Very common and common side effects

(may affect up to 1 in 10 people)

Uncommon side effects

(may affect up to 1 in 100 people)

  • Pain at injection site
  • Fatigue
  • Headache
  • Muscle pain
  • Chills
  • Joint pain
  • Fever
  • Diarrhea
Axillary swelling and tenderness (enlarged lymph nodes)
  • Pain at injection site
  • Fatigue
  • Headache
  • Muscle pain
  • Chills
  • Nausea / Vomiting
  • Axillary swelling and tenderness (enlarged lymph nodes)

When should I see a health care provider?

There have been a small number of reports of myocarditis and pericarditis (inflammation in different parts of the heart) following immunization with an mRNA vaccine. Most cases developed within one week of vaccination, have been mild and resolved quickly. Seek medical attention right away if you develop any of the following symptoms after vaccination:

  • Chest pain / feeling of pressure or tightness in your chest
  • Shortness of breath
  • Heart palpitations / irregular heartbeat

If you experience myocarditis or pericarditis after your first dose of an mRNA vaccine, speak with your health care provider or local public health unit for the most up-to-date recommendations regarding your second dose.

Things to remember after you receive the vaccine

  • Continue to follow local public health recommendations to prevent the spread of COVID-19, which include wearing a mask, staying at least 2 metres from others and limiting/avoiding contact with others outside your household.
  • Plan to receive your second dose as soon as it is recommended. Depending on where you receive your first dose, they may schedule you an appointment for your second. If an appointment is not scheduled for you, visit for a list of walk-in and appointment clinics.
  • The second dose is required to build adequate immunity and provide protection against COVID-19.
  • Avoid receiving any other type of vaccine or TB skin test until at least 28 days after receiving either dose of COVID-19 vaccine.
  • This guidance provides basic information only. It is not intended to take the place of medical advice, diagnosis or treatment, legal advice or legal requirements.
  • Please check the Middlesex-London Health Unit and Ministry of Health (MOH) website for updates, information and other documents.
Date of creation: March 16, 2021
Last modified on: July 27, 2021


1BioNTech Manufacturing GmbH & Pfizer Canada ULC. (2020). Pfizer-BioNTech COVID-19 vaccine: COVID-19 mRNA vaccine, suspension for intramuscular injection [Product monograph]. Retrieved from
2Moderna Therapeutics Inc. (2020, December). Moderna COVID-19 vaccine mRNA-1273 SARS-CoV-2 vaccine: Suspension for intramuscular injection [Product monograph]. Retrieved from