Dr. Penny Chan on the Pandemic: Vaccines

By: Dr. Penny Chan

Most of us now hear more about vaccines than we do about Covid-19. We hear “there is light at the end of the tunnel” of the pandemic and its lockdowns.

So we all want to know when we can get vaccinated. We have had concerns about vaccines getting to Canada and the apparent slowness of the vaccine “rollout.”

What are vaccines?

Vaccines, simplistically, are usually injections to prevent us from getting specific infectious diseases. They work by stimulating the body’s immune response so we can produce antibodies and/or T-cells that can interact with and inactivate the virus or bacteria (or other micro-organism or toxin that causes the specific disease). B-cells are also activated and “remember” the specific virus/bacteria, so if they see it again, they will rapidly “gear up” the immune response (to prevent the person succumbing to the disease).

Vaccine development is rapidly evolving and now there are a number of different types.

Types of vaccines

The main types of vaccines developed for protecting people against Covid-19 include:
1) Whole virus
2) Nucleic Acid (Messenger RNA or recombinant DNA)
3) Protein subunit

These can use viral vectors or nanoparticles to get the information into our cells. The mechanisms that these vaccines use to stimulate the immune response are different and are explained in detail elsewhere.(1)

Safety of vaccines

Unlike, in the past, when vaccines were produced by changing or inactivating the disease agent (virus or bacteria), most of the currently available vaccines do not contain the whole corona virus, or any living virus that can replicate within our body, or cause disease.

Before a vaccine can be approved for use, it has to go through a rigorous and comprehensive review process by the government (for us in Canada, it is Health Canada). A vaccine developer has to submit extensive data on the vaccine, its manufacture, its ingredients, and the results of studies done to show:
1) the safety — ie not toxic, in cells, animals and in healthy human beings,
2) its effectiveness at stimulating the immune response and
3) its effectiveness at preventing the disease.

These latter “clinical trials” have to include a wide range of people varying in age, race, sex and with varying health conditions. The size and heterogeneity of the population is of great importance to determining the effectivity, and frequency and type of side effects that may be expected. This is the reason developing and approving a vaccine is a lengthy complex process. It is important to note that the manufacturing process is also regulated so that there is quality control (all batches will be of equal quality and “strength”).

Considering the speed and number of vaccines developed, many people ask “can we be sure that the vaccines are safe?”, “have they gone through a sufficiently rigorous process of testing and review?”. As science evolves, new technologies become available and all stages of the process become more familiar, and can be modified for specific disease agents. We become more familiar with the types of effects that we need to look for. The other answer to these questions is, that although the review process is done by the governments (of the country, EU and WHO), it is (and should be) independent from political pressure (for speed or short cuts to the review process)

Differences in the vaccines currently available in Canada

Each of the vaccines available is different. Of particular note are
1) the effectiveness (at preventing the disease or serious consequences of the disease)
2) the risk of side effects, and
3) the storage conditions (to keep the vaccine active)
4) the number of doses and time interval between doses to provide the greatest protection.

Having said that, all the vaccines are more effective at preventing the disease than the traditional flu shots.

As we know, different people within our population have different susceptibility to the virus and disease development, depending on age, pre-existing health conditions and living conditions, and so will our bodies vary in the response to the vaccines. Importantly, “real-world data” are accumulating to better understand the effectiveness of the vaccines in different groups of people (eg, according to age and health conditions).

Vaccine roll-out and distribution

Currently, we have 4 vaccines approved for use in Canada and supplies are finally arriving. We have to consider how to distribute them to the population in the fastest most efficient manner possible. Consideration has to be given to:
1) Priorities eg. who is most at risk, and who are most likely to die if they have contact with the virus.
2) Delivery: who should give the injections (doctors, pharmacists, clinics) and where they should be given (mass vaccination sites, pharmacies, clinics, etc)
3) How people register and records kept (whether we should have vaccine passports)
4) accommodations for people who cannot use on-line registration processes, who cannot travel to clinics and, most importantly,
5) Communications to the public. The information has to be clearly communicated so people understand when, where and how they can get vaccinated, and particularly the importance of vaccination to the individual and to our whole community.

The vaccine development and approval process has been so fast and the information and recommendations keep changing as does the availability of supplies to Canada. This tends to lead to confusion in people’s minds, many questions (and sometimes a loss of confidence in the system)

What have we learned from this experience:

We need
1) Significant investment in basic research, development, and manufacturing capacity in vaccines domestically.
2) Centralized acquisition and fair distribution of appropriate vaccines for all communities across the country
3) Better information regarding
a. mechanisms for distribution,
b. importance (to both individuals and society) of getting vaccinated,
c. the review process and its dependence on the clinical trial data, (and these may change as more data becomes available)
d. why and how decisions are made.

Good luck everyone in getting your vaccination when it is available for you and stay safe. I am happy to answer any questions you may have.

Dr. Penny Chan is a retired immunologist and member of our Spadina — Fort York riding.