Vaccines and Side Effects

Your Immunity Pathway


A vaccination creates your immunity against a specific bacteria or virus without the need to have you get the disease first.

After getting vaccinated, you should develop proteins, called antibodies, which neutralize the infectious agent. A vaccine would stimulate your immune system to produce antibodies, exactly like you would, if you were exposed to a foreign disease.


It has been less than six months since the first Oxford-AstraZeneca vaccine was first given to a grandmother in England to be followed soon after, with the first Pzifer-BioNTech vaccine administered to a retired nurse in the United States.

There has been much confusion from various country protocols about who should get the vaccine and the timing for the second shot. All of us have become exhausted trying to keep informed. Here’s a summary of our present insights.

Current Vaccine Understanding

(Last updated April 20, 2021)

All the vaccines currently available are both SAFE and EFFECTIVE to prevent severe illness and death due to the wild type (original strain).

Recent clinical evidence suggests that waiting beyond the 21 days (Pzifer) and the 30 days (Moderna and AstraZeneca) provide sufficient continued protection with only the first shot.

New variants of concern (VOCs) contain mutations from the wild type (original strain), which increases the virus’ ability to be more contagious, lethal and possibly, increase vaccine resistance

More boosters in the future will likely be required to manage new VOCs

Duration of Immunity

Studies now suggest that antibodies after the second shot are still present at least six months post-vaccination.

What determines the efficacy of your post-vaccination immunity are:

  1. Quantity of your antibodies against the wild and variant strains
  2. Quality of how well your antibodies can bind to the virus and neutralize the wild and variant stains


Common COVID-19 Vaccine Q & A

Herd immunity is when a high proportion of individuals are resistant to the spread of the virus due to vaccination. The level of herd immunity needed can vary from disease to disease however for COVID-19 we will require at least an 80% vaccination rate. If the pandemic worsens that rate could increase.

mRNA vaccines are like CD players that can play any kind of CD – classical music, rap or pop. The scientists had the CD player before COVID-19 hit due to previous research being done on mRNA technology. Once they figured out the Coronavirus CD, they could place it into the player and make the vaccine a lot faster than before, since they used what was known and built on it.

Both Pfizer and Moderna have released their ingredient lists, which can be found online. Neither vaccine contains mercury, formaldehyde, aluminum, or fetal cells.

Pfizer-BioNTech COVID-19 vaccine

Moderna COVID-19 vaccine

Depending on which vaccine the answer varies.

Both the Moderna and Pfizer series requires at least two vaccines.

According to a document submitted to the FDA, the Moderna vaccine can provide 50.8% efficacy of the first dose on days 1-14 and then 92.1% post 14 days for an overall 80.2% protection after one dose compared to 95% after the second dose 28 days apart.

The Pfizer vaccine after one dose was shown to have an efficacy of 52% verses the above 90% after two doses 21 days apart.

It is unknown whether the immunity from a single vaccine would continue or drop off as no research was done to study this. Both briefing documents submitted to the FDA state that the available data “cannot support a conclusion on the efficacy of a single dose of the vaccine”.

The Janssen (Johnson & Johnson) vaccine that released their Phase three clinical trial results shows an overall efficacy of 85% against severe disease and 66% after moderate to severe disease, 28 days after vaccination.

There is little to say about extending the interval between doses as the trials conducted did not test for the extended interval time, we just don’t know how the efficacy of a vaccine continues past a certain stage. We will all be looking at the UK to see how this extension has affected their vaccination efficacy as they are one of the first to administer this new schedule.

No clinical trials have been done by Moderna or Pfizer to look at how long immunogenicity lasts following one does. All Pfizer vaccine trial participants received the second dose 21 days after their first, Pfizer has stressed that there is no evidence of efficacy for the first dose after 21 days. (Mahase, 2020)

Based on unpublished data available to the National Advisory Committee on Immunization through Health Canada for both the Pfizer-BioNTech and Moderna vaccines, there was no difference in vaccine efficacy between the people who got their second dose at day 19 and the people who got it at day 42. (Tauh, Mozel, Meyler, & Lee, 2021)

It is recommended by the Government of Canada to follow the original dosing schedules however due to logistical constraints it may not be possible. (Tauh, Mozel, Meyler, & Lee, 2021)

There is no evidence on the interchangeability of the COVID-19 vaccines. Studies are currently under way, but no results have yet been released.

Carter, A. (2021, Jan 20). Debunking myths: Ontario doctors explain why most people should get COVID-19 vaccines. Retrieved from CBC:

Centre for Effective Practice. (2020). Answering questions about COVID-19 vaccines: a guide for healthcare providers. Centre for Effective Practice.

Cleveland Clinic. (2020, Dec 23). 9 Common COVID-19 Vaccine Myths Explained. Retrieved from Cleveland Clinic:

FDA. (2020). Vaccine and related Biological Products Advisory Commitee: Pfizer-Biontech COVID-19 Vaccine (BNT162, PF-07302048). Pfizer.

FDA. (2020). Vaccines and Related Biological Products Advisory Committee Meeting: FDA Briefing Document Moderna COVID-19 Vaccine. ModernaTX, Inc.

Henry Ford Health System Staff. (2020, Dec 21). 10 Myths About The COVID-19 Vaccine That Aren’t True. Retrieved from Henry Ford Health System:

Iacobucci Gareth, M. E. (2021). Covid-19 vaccination: What’s the evidence for extending the dosing interval? The BMJ .

Mahase, E. (2020). Covid-19: Pfizer vaccine efficacy was 52% after first dose and 95% after second dose, paper shows. The BMJ.

Moore, J. P. (2021). How do you take your vaccine—one lump or two? BMJ Opinion.

Tanula, M. (2020, Dec 9). COVID-19 vaccine myths debunked. Retrieved from Mayo Clinic:

Tauh, T., Mozel, M., Meyler, P., & Lee, S. M. (2021). COVID-19 VACCINE DOSING SCHEDULE – WHAT IS THE EVIDENCE? BC Medical Journal.

Vaccine Side Effects

There are approximately 6 cases of unusual blood clots reported to the CDC in about 7 million vaccines administrated to date (1 per 1 million) of the Johnson and Johnson vaccine. Canada reported its first case recently of a vaccine-related blood clot in Quebec, Canada, after 700,000 Astra Zeneca doses were administered and another case soon followed by a British Columbia resident.

Experts call the condition vaccine-induced immune thrombotic thrombocytopenia (VITT) or vaccine-induced prothrombotic immune thrombocytopenia (VIPIT).

VITT patients experience life-threatening clots but also hemorrhaging at the same time. Early research suggests this unusual blood clotting combined with a low number of blood-clotting cells called platelets.

A study led by U.K. hematologist Dr. Marie Scully of 22 patients who received the AstraZeneca’s vaccine and later developed VITT were found to have had an unusual antibody response. Patients created anti-PF4 antibodies that had only been seen before as a rare reaction to using the common blood thinner heparin.

Both AstraZeneca and Johnson and Johnson vaccines use a common cold virus (adenovirus) as a carrier for a piece of the COVID-19 virus. Experts suspect the body’s response to such a combination of viral vectors might cause a hyperimmune/inflammatory response to trigger a blood clot; a reaction by the immune system with platelets to cause uncontrolled clotting.

Putting VITT Risk into Perspective

Compare the risk of VITT following a COVID-19 vaccine against:

  • Overall chance for a blood clot is 1 per 1000 depending on pre-existing health conditions
  • Use of birth control or estrogen hormone pills increases a woman’s blood clot risk to 3-9 per 10,000
  • After an airplane flight, the chance for a deep vein thrombosis clot is 2-10 per 100, depending on personal risk factors and length of the flight


Vaccines in Canada

Currently approved vaccines in Canada are Pfizer, Moderna, AstraZeneca*, and Johnson & Johnson.

*ALERT About AstraZeneca Vaccines:

Recently, Denmark, Norway and Italy suspended the use of the AstraZeneca vaccine citing concerns for the risk of developing blood clots.

Earlier, Austria, Estonia, Lithuania, Luxembourg and Latvia suspended the use of one specific batch of the AstraZeneca vaccine — batch ABV5300 — after “a person was diagnosed with multiple thrombosis,” according to EMA.

This points to the fluid concerns of not only side effects of certain vaccines but also the batch used. Hence the importance for the use of the Immunity Passport App to track these data points and more.

Vaccines mount an immune response. This means that to some degree, we will all experience inflammation, caused by the vaccination which results in symptoms such as aches and pains, fever and chills. For those with pre-existing cardiovascular factors (high cholesterol, high blood sugar and diabetes, auto-immune conditions, and proven heart disease, stroke or blood clotting history), there exists a higher risk of a more pronounced inflammation effect in blood vessels, resulting in blood clots.

We know COVID-19 causes clotting problems. Hence the higher risk of post COVID-19 related heart attacks and strokes.

Pending approval vaccine in Canada is Sanofi.

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