Speed Response Series

Q: Do vaccinated people transmit at the same level as unvaccinated?
A: NO!

  • You are FAR LESS likely to be infected with Covid-19 if you are fully vaccinated.
  • While transmission was not an end point in the clinical trials, we do also see that vaccinated are less likely to transmit.
  • Data shows that even if you are infected, you clear the virus more quickly if you are vaccinated vs unvaccinated. Vaccinated people are less contagious over time.
  • New data also shows that fully vaccinated people with Covid-19 infection are less likely to infect their close contacts than unvaccinated.







Q: Do we need to worry about long-term side effects with vaccines?
A: NO!

  • With vaccines, we see any side effects within 8 weeks of getting the vaccine.
  • This is because vaccines work differently than other medications, they don’t linger and are removed from your body quickly.
  • Vaccines work by training your immune system. So once they do their job, the rest of the work is done by your immune system. By 8 weeks, the immune response stabilizes and your immune system goes back to baseline.
  • This is also why most vaccine side effects are typically immune-mediated.

Q: How do vaccines work?

  • When your body encounters a new disease-causing organism, it takes a while to ramp up the immune defense system. This allows the organism to cause damage to the body.
  • But, when you vaccinate, you put a small amount of the inactivated/weakened disease-causing organism into the body, so that the body ramps up an immune response against it.
  • So later if you body comes across it, it recognizes, responds immediately to fights it.
  • Vaccines provide protection because they cause your immune system to make antibodies and memory cells, so that when you’re exposed to the real infection your immune system can quickly protect you.

How to counter ‘Do your research?’

  • We cannot form opinions based on individual publications or studies but instead need to look at the totality of evidence.
  • All data is not created equally. There is a hierarchy of evidence based on type, quality, robustness and statistical power.
  • Consensus guidelines and recommendations are a huge undertaking and not made lightly. They are the very definition of evidence based and involve robust literature searches, comb through all the data and formulate the recommendations taking into account the entirety and quality of information available.
  • A Google search is simply not research.

How to counter ‘I trust my immune system, so I don’t need a vaccine?’

  • We give vaccines because we trust our immune system!
  • Vaccines provide protection by getting your immune system to make antibodies and memory cells, so that when you’re exposed to the real infection your immune system can quickly protect you. All the hard work is done by your own immune system.
  • But remember that it is your own uncontrolled and impaired innate and adaptive immune response that causes Covid-19 acute respiratory distress syndrome (ARDS) after an infection.
  • Important to guide our immune response to have a measured response.

What are some of the reasons to vaccinate adolescents?

  • Studies show the benefits of vaccinating adolescents far outweigh the risks in terms of hospitalization, death and long Covid.
  • Risk of myocarditis has been found to be much higher with Covid-19 infections vs vaccinations.
  • Indirect benefits of vaccinations will reduce onward transmission to household members, especially if immunocompromised or too young to be immunized.
  • Will allow us to get closer to herd immunity and offer community wide transmission.
  • Will reduce the disruption of education or time with friends by reducing outbreaks and subsequent isolation/closures.







Q: Do Covid-19 vaccines cause variants?
A: NO!!

  • Most variants thus far has emerged before vaccinations were rolled out, all in areas that did a poor job of controlling infections.
  • Variants are driven predominantly and overwhelmingly by those who are unvaccinated, via uncontrolled spread to other unvaccinated people.
  • Viruses are sloppy, the more they replicate, greater chance a significant mutation occurs.
  • Concerns of Antibody Dependent Enhancement (ADE) are unfounded. Bulk of hospitalized cases are in the unvaccinated. If ADE was indeed a concern, we would have seen this occur already but haven’t.

Q: Should I wait for my almost 12yo to get full dose vs a pediatric dose?

  • Getting vaccinated as soon as possible is the best way to protect your children.
  • Vaccine doses are not based on weight, because immune response is not weight dependent.
  • Dosage is determined by stepwise de-escalation and is the dose that creates a strong immune response with minimal side effects.
  • This is different from regular medications, where weight plays a role in both physiologic effects as well as metabolism and clearance.
  • The studies included a wide range of children, and the dose that was established was found to be effective for all the age ranges included.
  • NACI will likely provide more recommendations once Health Canada approves.

Q: What are horseshoe crabs and how are they used in vaccines?

  • Horseshoe crab blood is used to test sterility, it is not actually present in the vaccine.
  • Their unique copper-based blue blood contains a substance called Limulus Amebocyte Lysate, which forms clumps in the presence of bacterial toxins and is therefore used to test for bacterial contamination in vaccines. Synthetic versions are available but not widely used.
  • Horseshoe crabs are not endangered, but some do die after extraction of their blood. More horseshoe crabs die when used as fishing bait and loss of natural habitat.

Why are cases in Ontario lower than modelled or expected?

  • While vaccines are working well and we have a high rate of uptake (73% across entire population), other provinces and countries with similar vaccine uptake have not fared as well.
  • This is because we have continued to employ non-pharmacologic interventions and kept public health measures in place:

– We are still masking indoors and in schools. We saw in provinces that dropped masking too soon, such as AB, BC and SK, cases are rising exponentially.

– While Ontario did reduce some PCR testing capacity, it also added rapid antigen testing to businesses, big indoor arena events (but we should now extend to schools).

– We also put vaccine certificates into place.

  • That said, we are still in a precarious position. We must continue to be vigilant until we have majority of the population vaccinated.

The vaccine is NOT ‘experimental’

  • An experimental drug or vaccine is when it has not yet been approved for use.
  • The Covid-19 vaccines are either fully approved or approved via EUA/Interim Order, which means they are authorized to be marketed.
  • A drug is not allowed to be marketed until they have gone through efficacy, safety and quality studies, which then undergo thorough, critical review and due diligence by regulators.
  • All approved vaccines have completed and published data from the Phase 2/3 trials. These trials will continue in order to monitor for long-term efficacy.
  • All approved vaccines went through the process of animal and Phase 1 trials prior to moving into Phase 2/3 trials.
  • Anyone claiming the vaccines are ‘experimental’ is spreading false information – this should be your first red flag to alert you that the source is not credible.

Vaccines DO KILL the virus causing Covid-19

  • Rumours are being spread that vaccines do not kill the virus that causes Covid-19, and only infections do. This is blatantly false.
  • Reminder to read my post on how vaccines work, but this is Vaccinology 101 – when your body encounters a new disease-causing organism, it takes a while to ramp up the immune defense system. This allows the organism to cause damage to the body. But, when you vaccinate with the mRNA vaccines, you give a recipe to the body to make a modified version of the spike protein, so that when the body comes into contact with the actual virus, it recognizes the spike protein and quickly ramps up an immune response against it.
  • When you vaccinate and are exposed to the virus, you get a rapid increase in binding and neutralizing antibodies. Whereas these take a while to produce during an infection.
  • Antibodies that prevent entry into cells are called neutralizing antibodies. Once a virus has been neutralized by a neutralizing antibody, it is broken down quickly by white blood cells, and excreted out of our body.
  • Non-neutralizing are called binding antibodies, these are are also important. They bind to the virus and then puts out an SOS signal for other immune cells, which are then destroyed by recruited immune cells.
  • Vaccines result in higher number of binding and neutralizing antibodies than what is seen after infections with Covid-19.
  • Immunity generated from vaccines is indeed very effective at killing viruses. In fact, previously infected individuals have a 5.5x higher odds of re-infection vs those fully vaccinated.



2- https://www.jwatch.org/na53802/2021/07/08/people-with-past-covid-19-benefit-immunization

3- https://wwwnc.cdc.gov/eid/article/27/9/21-1042_article



How much protection does one dose of the vaccine offer kids?

  • One dose is better than zero doses!
  • We don’t have a good idea of the efficacy after one dose in children. This is because in the pediatric trials, all participants received the second dose 3 weeks after the first.
  • In adult studies, one dose of Pfizer showed 36-56% (1,2) efficacy against Delta for symptomatic illness, efficacy for severe illness thought to be higher (2).
  • Important to continue to mitigate risks as we head into holiday season. This includes masking, testing, ventilation, distancing etc.
  • Two doses key to be fully protected.
  • NACI recommends 8 weeks interval. Data shows better immunity & possibly lower myocarditis with longer intervals. However, must weigh this against being fully protected, especially if community cases high & in the face of a new variant.

1: https://www.nejm.org/doi/full/10.1056/NEJMoa2108891
2: https://www.medrxiv.org/content/10.1101/2021.06.28.21259420v2.full

Endemic or ‘living with the virus’ doesn’t mean we ignore it altogether

– Endemic diseases can and do still cause significant mortality and morbidity around the world eg: malaria, tuberculosis. Endemic does not mean a disease is ‘mild’ either.
– Endemic diseases can cause outbreaks, outbreaks can turn into epidemics, which can spread globally.
– This means that we cannot ever simply ignore an endemic disease. In fact, quick mitigation strategies are critical to ensure that outbreaks of endemic diseases are quickly stamped out.
– Just because a disease is endemic does not mean we do little to nothing about it.
– Even when Covid does eventually becomes endemic, we will have durations when we may need to revert back to short mitigation strategies to control spread.
– Importantly, Covid is not endemic yet, as much as we wish it is. It is still spreading in an uncontrolled manner. 

Our mitigation strategies were necessary and did save many lives.

– One of the primary reasons for the public health mitigation strategies (masking, temporary lockdowns etc) we used in Canada has to do with our lower hospital capacity (healthcare has been systematically defunded for decades)

– As a comparison, the US have a larger hospital capacity which likely played into them using a more relaxed strategy

– This is why their per capita Covid death rate is one of the highest in the world: Canada: 920 per million USA: 2755 per million

– If we had the same mortality rate as the US, we would have lost an additional 70,000 Canadians (not age-standardized)- Even more people would have died due to other urgent issues as well – such as heart attacks, sepsis etc. due to maxing out healthcare capacity

– Not much comes close to this level of human life loss in recent history