Episode 67 — COVID-19 Vaccine Facts with Dr Alyson Kelvin

Summary written by Dagny Reese

this weeks episode, listen to Dr Bahijja talk with Dr Alyson Kelvin from VIDO-InterVac about COVID-19 vaccination, such as the various manufacturers, the dosing, or new vaccines for the emerging variants.

Photo of vaccine bottles by Daniel Schludi.

Dr Bahijja: Which lasts longer, immunity after getting COVID-19 or protection from COVID19 vaccines?

Dr Alyson: To stress this point — we must remember this is a brand new virus as of a year ago, so our understanding of how long immunity lasts after infection is limited by the time frame. Results are coming in suggesting that some patients have antibodies up to 8 months after infection, and 3 months for vaccination. We definitely still have a limited understanding about what this means and how long lived this immunity will last. Vaccination, of course, is always preferable as you do not need to get the disease to acquire immunity.

Dr Bahijja: How many vaccines are currently available and approved, and how do each work?

Dr Alyson: This is an interesting question to think about, as depwending on the country there may be vastly different vaccines available to you. For example, in the UK, there are 3 vaccines currently — two are mRNA based and one is a viral vector. Currently in Canada and the US, we currently only have the two mRNA based vaccines. In China, there are a couple available, neither being mRNA or viral vector — I believe they are both live inactivated vaccines. Russia and India both have their own vaccines they have developed. There are also many more to be approved soon, such as the Johnson & Johnson Vaccine or the Novavax vaccine, which is peptide based, similarly to the yearly flu shot.

Dr Bahijja: Will any of the vaccines work against any new COVID19 mutations/variants?

Dr Alyson: Right now, this is being investigated. Moderna highlighted recent evidence showing it is likely their vaccine will protect against the new variants, such as the UK variant. Other independent work has shown the vaccine generated antibodies are able to neutralise many of these variants. I am optimistic we will see protection with the currently available vaccines with the new variants.

What are antibodies? Antibodies are a type of protein that is secreted in our body. They are randomly produced with highly variable regions — some of these regions, by chance, might bind to a virus or other pathogen in your body. They are produced by B-Cells, a type of immunological cell. B-cells also possess non-secreted antibodies, called B-cell receptors, that are anchored to their membranes. Specialised B-cells, called plasma cells, can produce vast quantities of antibody and circulate them throughout our bodies.

Dr Bahijja: At some point will there need to be a new vaccine for the specific variants?

Dr Alyson: I think this is currently on everyone’s mind currently, if they are working in COVID-19 vaccine development. Not just for developing the specific vaccines for the variant, but generally having a flexible and easily modifiable vaccine platform and having a vaccine with very broad protection. For example, a vaccine that could protect against future variants or protect against future coronaviruses.

Dr Bahijja: What percentage of the population needs to get vaccinated to get herd immunity?

Dr Alyson: This really does depend on the virus. For example, measles is highly infectious and easily passed from one person to another. In that case, to achieve herd immunity, we need a higher level of herd immunity — over 95% in the case of measles. With Polio, a slightly lower percentage is necessary, perhaps around 80% as an estimation. Anthony Fauci, the head of the USA’s National Institute of Health has estimated over 85% of the population must be vaccinated to have herd immunity. This level may also change in the future, with a higher percentage required, with the emerging variants. […]

Dr Bahijja: How safe are the vaccines and why compared to other vaccines for infectious disease were they so quick to develop?

Dr Alyson: With this vaccine, I really want to go back to me being an emerging virus researcher. Many of my colleagues have been researching coronaviruses for over 30 years, and really, started narrowing down and undertsanidng what is going on with the SARS like viruses, such as SARS and MERS. We have actually been developing vaccines for coronaviruses for a very long time and a lot of what we know about the characteristic spike protein from SARS-1, MERS and now SARS-CoV-2 comes from that.

We already knew how to stabilise the protein and the usage of mRNA vaccines, for example, previous to this. mRNA vaccines have been in the work for quite awhile, and have been developed as a highly flexible vaccine technology [for usage in situations just like this pandemic]. Of course, it had to be tailored for the SARS-CoV-2 virus, but the technology was pre-existing, which is what led to the quick development. Now that millions of people have been vaccinated, we are quite sure of its safety profile as well.

What is mRNA? mRNA, also known as messenger RNA (thus the “m”). When our cells are producing proteins to carry out functions in our body, pre-existing proteins read our DNA and produce a “copy” of the DNA using RNA. This messenger RNA can then be read by something called a “ribosome” in our cells, providing instructions for the different amino acids to be included in the protein in a specific order.

Photo of vaccine bottle by Hakan Nural.

Dr Bahijja: Is the vaccine safe in pregnant women and does it affect fertility?

Dr Alyson: When new vaccines are first available, oftentimes pregnant women are not included in the clinical trials and vaccine development. This is what happened with the 2009 Influenza vaccine, and this is quite similar. In the phase 3 trials, there were some people who were vaccinated and were unknowingly pregnant or who got pregnant soon after, so we were able to review the data and it seems to have no risk. Although there were previous restrictions, this has now been reconsidered given this data, as there are no known safety risks.

To also elaborate, the mRNA used in these vaccines is very unstable and does not exist in the body for very long. Due to this, it is unable to integrate its own genome into the DNA and it only expresses the protein. There is no risk to your sex cells/gametes or to your own DNA.

What are sex cells? Sex cells, also known as gametes, are reproductive cells. In humans, our sex cells are normally haploid, meaning they carry half of a genome that a normal non-sex cell would carry in the body. They are produced via a process called meiosis, which is somewhat similar but also distinct from mitosis, which is how most of our cells replicate. Examples of sex cells include sperm and ovum.

Dr Bahijja: What have been the commonly reported side effects or allergic reactions?

Dr Alyson: The most commonly reported side effects so far have been quite typical, and the type of symptoms we want to see [as they indicate a proper immune response to the spike protein]. This includes soreness in the arm, possibly a fever, soreness in areas associated with the immune response (such as the armpits). [This allows for “priming” of the immune system] so that it is prepared upon any future exposures to the virus.

Photo of person receiving vaccine by the CDC.

Dr Bahijja: What’s inside the vaccine? I was involved in a clubhouse discussion about the excipients in the vaccine and the use of the polymer PEG, polyethylene glycol?

Dr Alyson: The components of the mRNA vaccines are the mRNA, which is genetic information that allows your body to produce specific proteins (Note — this does not result in any changes to your own genome, which is comprised of DNA, not mRNA), as well as stabilisers to prevent the breakdown of the mRNA, which is relatively unstable. Therefore, we wrap the mRNA in a bubble of fats or lipids, however, these can also be unstable or easily broken down, so the PEG is used to stabilise these lipids. This allows for a safe delivery of the mRNA so that your immune cells can produce the needed antibodies. Sugars and other additives are also added so that it is safe to be injected into the muscle.

Some people can have allergies to PEG, however, the associated risks of allergic reaction are low, as you are observed in a healthcare setting. So far, the few who have had reactions to PEG have all fully recovered.

What is an allergy? An allergy, also known as a hypersensitivity reaction, is an example of an inappropriate response of the immune system to harmless stimuli, such as peanuts. There are several different types of hypersensitivity reactions, such as Types 1–5, which are characterised by the different immune cells and antibodies. The immune response you are likely most familiar with is “Type 1”, involving IgE antibodies and the release of histamine from immune cells called “Mast Cells”.

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Monday Science | Weekly Podcast

An engaging podcast bringing you the latest research in Science, Technology and Health.Hosted by award winning scientist Dr Bahijja Raimi-Abraham.