COVID Vaccine 101 – Everything You Need To Know

As many of you know, I worked in public health for over 20 years. It probably goes without saying that I’m pro-vaccine. While being pro-vaccine I recognize that many people are vaccine hesitant, vaccine deniers, or just plain leery of vaccines.

Information is power as they say, so I’d like to share some background on vaccines and then look more particularly at the COVID-19 vaccines.

A Brief History of Vaccination

First there was variolation….

It’s interesting to note that vaccination as a practice was first done in China over a thousand years ago. In the western world, vaccination was initially practiced in the 16th century and seems to have come via the Ottoman empire. The earliest version was called ‘variolation’ and it involved exposing an individual via a cut or scrape to infectious lesions from an infected person.

It was a kind of controlled exposed to the actual disease and was first used to prevent smallpox.

…and then there was vaccination

Vaccination is a different process. With variolation there is controlled exposure to the actual disease-causing virus or bacteria. But with vaccination we are looking to protect someone without exposing them to the actual disease. Vaccination was first done in the late 18th century. It was observed that individuals who were exposed to cowpox, a pox virus that infects cattle, were immune to smallpox which is frequently deadly in humans. Cowpox doesn’t cause disease in humans but exposure to cowpox will stimulate the human immune system to produce antibodies against it, nonetheless. As it turns out, cowpox antibodies are similar enough to smallpox antibodies that vaccination with cowpox (again it does not make humans sick) prevents smallpox.

So, vaccination is a process by why something similar to an infectious agent is presented to our immune system. Our immune system reacts to it because it is foreign. When it reacts it produces antibodies. Antibodies then provide future protection against that infectious agent. Vaccination is not about infecting an individual, it’s about training the immune to protect you without having to get sick in the first place.

Human Immune System 101 – Antibodies

But let’s take it back a step. What exactly is an antibody? Where does an antibody fit into the roles played by our immune system?

If you like, antibodies are like first responders. When there is a crisis, they are the component of our immune system to react first. They are a type of protein that specifically recognizes an invader, and they attach themselves to the invader. They are like a flare that alerts the other elements of the immune system that an invader is present. After the rest of the immune system is aware, we have many different ways we kill invaders – killer T cells, poisonous cytokines etc. But antibodies are the advanced warning system – like radar.

If we don’t have antibodies, it can take the body quite a while to realize an invader is present. Without radar, we’ll only know we’re being bombed once the bombs are upon us. Without early warning the delay is enough to give the invader a big advantage – it has time to multiply and grow its army of invaders before our immune system gets after it.

If we’re lucky our immune system is fast and effective and kills off the infectious pathogen before it overwhelms our body. If we are unlucky or have a weak immune system, the invader wins the day and we have long term illness or we die. If we don’t have antibodies against a specific infectious illness, we eventually make them during that battle, some early antibodies (IgM for example) to get the process going, some later antibodies to protect us in the future should we face that invader again (IgG for example).

Antibodies will stick around a long time, but not necessarily forever. If have antibodies to an illness but we are not exposed to that infectious agent for a very long time our body will eventually stop making those specific antibodies and we’ll be vulnerable to that illness again. This is why, for example, common vaccines like diphtheria and tetanus must be provided every 10 years in adulthood. In infants and young children, their immune systems are immature so they may need multiple doses of vaccine in short order to keep reminding the immune system to make antibodies against common childhood diseases like polio or rubella (german measles).

And then there was COVID-19

COVID-19 has an advantage because it’s a brand new (novel) virus to humans. Because it’s a novel virus, we do not have antibodies against it or even something close enough to recognize it. Our body hasn’t seen it before and we have no first responders or a flare to alert the immune system. By the time our immune system is aware of the infection, COVID-19 has already invaded and co-opted millions of cells in our body to make copies of itself. This means we end up with such a high viral load by the time the immune system is aware, our immune system goes into full battle stations and throws everything at it. We go from all’s well to immune system RED ALERT.

The consequences of RED ALERT

An immune system in overdrive has consequences of its own. Your immune is powerful and the cytokines it produces for example, are poisonous not just to infectious invaders, but also to your own body. Your own immune system can kill you before it’s able to wipe out an invading virus. This was a common event in the 1918 pandemic. The immune system reacted dramatically to the Spanish flu particularly if it was a young and healthy immune system which why so many healthy young people died in the 1918 pandemic. Immune system reaction is one of the reasons dexamethasone (a powerful immune suppressing steroid) and other potent immune suppressors are used to treat COVID-19. These drugs suppress your immune system to stop it from killing you.

Why do teens and kids suffer less with COVID-19?

What about younger people – teens and kids? Why is COVID-19 less severe in them? This is because they have less of the cells in their body that the spike protein on COVID-19 attaches itself to. The particular cells in the nasal passages, eyes, throat and lungs that COVID targets are much, much fewer in number in children and teens. So, if they are exposed to COVID-19 their viral load is much smaller and their immune system has an easier time going after the virus since it has only the occasional enemy soldier to target rather than a whole army to face.

Finally, COVID-19 Vaccine

Getting back to vaccination, it’s all about the antibodies. Vaccination involves presenting a protein to your immune system similar to the spike protein on the COVID-19 virus. When your body sees this protein it chops it up into little pieces and makes various antibodies which will recognize those individual pieces of protein should your body ever see them again. That protein presented to your immune system has no capacity to infect you. It is not the virus itself, just a

piece of protein similar to the spike protein on COVID-19’s coating. This is why you can never catch the infection itself from the vaccine. Remember, vaccination is not about infecting the individual, it’s about training the immune system by showing it something similar but not infectious.

What about this mRNA?

All living things require RNA (ribonucleic acid) or DNA (deoxyribonucleic acid). mRNA is just one type of RNA found in viruses (messenger RNA). RNA and DNA are the instructions that tell living cells and other agents like viruses how to operate and reproduce – like computer code. In the case of COVID-19 the virus has RNA. We’ve all seen pictures of the coronavirus with its spiked exterior coating. Basically COVID-19 is a strand of RNA surround by a fat layer coating with spiked proteins attached to it (because it is fatty coated it is fortunately very easy to wash away with soap and water). The spike protein allows the virus to attach to certain cells in the nose, throat, eyes and lungs and allow entry of the viral RNA into that cell. The RNA instructs the cell to use its own cellular apparatus to make more COVID-19 virus. And so on. Our own cells become virus factories.

So how does this vaccine actually work?

In the case of mRNA vaccines, vaccinologists have created a section of mRNA that carries instructions on how to produce a part of COVID-19’s spike protein. If you inject that bit of vaccine mRNA into an individual it is taken up by immune cells in the body. The immune cell machinery reads the mRNA instructions (or code) and produces the protein. The protein produced is only a small bit of the spike protein and has no capacity to cause illness. However, the immune system sees it as foreign and launches an immune response which includes creating multiple types of antibodies against various sections of that spike protein. If that individual, then contacts genuine COVID-19 the antibodies alert the immune system (send up a flare!) and the COVID-19 is immediately destroyed. This type of vaccine is simple, elegant, and effective.

Contrary to popular belief, RNA vaccines are not new; they have been studied and trialed since the 1990’s and found to be safe. What’s new is how rapidly the COVID-19 vaccine was developed after the genetic code of the virus was sequenced. The speed at which trials were initiated and the number of different trials was also unprecedented. The fact is that the COVID19 vaccine has had much more testing prior to approval than other vaccines in the past.

If there is a downside to this elegant new type of vaccination, it is the fact that RNA is very unstable and breaks down very easily. This is why the currently approved vaccines must be kept in such a deep freeze and why they must be administered quickly after they are thawed. Once injected into an individual the mRNA also breaks down quickly in the body, typically within a couple of days. But even a day or two of exposure is enough time for the immune system to react and produce antibodies.

The AstraZeneca and Moderna vaccines use traditional methods to make vaccine – similar to what’s used to make flu shots. This involves taking a different coronavirus ( one that causes common cold in monkeys) and inserting Covid 19 genes into that virus. This monkey virus can’t make you sick but your body will see it as foreign and produce antibodies against it including the Covid parts. This type of vaccine is proven, reliable and effective.

What about variants?

Viruses are very simple particles so they are nimble at adapting to their environment. When a virus replicates itself it sometimes makes small changes to its RNA or DNA while copying. These copy errors or ‘mutations’ may benefit the virus or make it a less effective pathogen. This new version of the virus is referred to as a ‘variant.’ When the mutation leads to a more effective pathogen it’s a real problem for us. The mutation can make the virus more infectious, more able to evade our immune system and therefore replicate quickly. More virus in the body means a sicker individual and a greater likelihood of serious illness and hospitalization.

Variants and Vaccine

Vaccines are designed to alert the immune system to the presence of the virus. The current COVID vaccines are generally effective against the currently circulating variants. Some vaccines are more effective against certain variants than others, but overall the currently available vaccines will reduce illness and risk of hospitalization for all variants. Nonetheless, there is concern that if individuals don’t get their second vaccine dose (booster) they may not have sufficient protection especially with respect to the variants. The length of time between first and second dose of the COVID vaccine and effectiveness for preventing variant illness is being carefully monitored by vaccine specialists and health authorities. Currently, the most commonly circulating variant in Ontario is the B117 (British) variant which appears to be susceptible to all the currently available vaccines.

What about blood clots with certain vaccines?

It has been widely reported that the AstraZeneca vaccine and the John & Johnson vaccine are associated with an increased risk of rare brain blood clots (vaccine-induced prothrombotic immune thrombocytopenia). This same risk has been seen with certain medications like heparin. The risk appears to be primarily in premenopausal women (women under the age of 55 years).

This risk of a blood clot with these vaccines, while documented and known, is extremely rare. In Canada, there has been four documented cases to date of blood clotting thought to vaccine related among 1,000,000+ doses of the Astra Zeneca vaccine given (J&J is single dose and has been Health Canada approved for anyone aged 18 years and older with first shipments due to arrive April 27).

Despite the four cases, Health Canada maintains that the benefits of the AstraZeneca vaccine outweigh the risks of infection with COVID-19. The agency approved the use of the vaccine for those 18 years old and over. The National Advisory Committee on Immunization recently updated its recommendations for AstraZeneca to anyone aged 30 years and older (previously they recommended aged 40 yrs and older).

A recently published analysis in a respected British medical journal showed the risk of this type of blood clot to be 4/1,000,000 for Pfizer/Moderna and 5/1,000,000 with AstraZeneca and 39/1,000,000 in COVID patients. It’s important to note that this clotting disorder has been observed in individuals receiving both types of vaccines but the risk is 10 times higher among COVID patients. Most of these rare blood clots have occurred in premenopausal women, especially under age 40.

Given the rate of COVID-19 infections in Ontario, and the dominance of variants, the benefits of vaccination with the AstraZeneca vaccine far, far outweigh the risks in all age groups. The same holds true for all the COVID-19 vaccines. Because COVID-19 illness is more severe in women over 40 than under 40, in Ontario only those under 40 are currently restricted from having AstraZeneca vaccine due to the rare clot issue and this restriction could be lifted in the future. This restriction with AstraZeneca exists only out of an abundance of caution until yet more data is collected.

What about vaccination in children?

When COVID-19 vaccine trials were initiated they did not include certain populations (for eg. children, pregnant women) and therefore the currently available vaccines have not been studied in these individuals. Nonetheless, pregnant women are now encouraged to be vaccinated because they suffer a higher proportion of COVID related severe illness, hospitalization and preterm birth. So, while the vaccine has not been specifically studied in pregnant woman, they are being provided the same vaccination as women in general.

Children are different. They have immune systems that function somewhat differently depending on their developmental stage as well as smaller body size. Thus, vaccine double blind randomized control trials must be done to determine safety, dosing and effectiveness in children. Trials started about a month ago with Pfizer and Moderna. They will begin trials in older children and then work their way backwards to infants. Early data suggests that children form a strong immune response and develop good protection with vaccination.

When the time comes, why should I get my child vaccinated?

While children rarely have serious illness with COVID-19, a small but significant number of children develop a severe multi-system inflammatory syndrome. Pediatricians around the world are reporting increasing admissions to hospital related to this potentially fatal illness. The other concern is that whilst children may be mildly ill or even asymptomatic with COVID-19, newer variants are causing more significant illness in children and teens and greater infectiousness. Children and teens spread illness even when asymptomatic. Thus, in order to truly achieve herd immunity children and teens will likely need to be vaccinated as well and as soon as researchers can confirm safety, dosing and effectiveness.

Well, that’s the not so short course on COVID, immunity and vaccination. Hopefully this information has been helpful and answers a few questions. Vaccine hesitancy is most commonly a problem of information and trusting where that information is coming from. It’s important to ask questions and seek reliable sources for information. Determining what’s reliable? That’s another course!