Part of finding our way through the COVID-19 pandemic is balancing our need for this to just be over already with also considering the latest recommendations from medical experts.
We could all use a little light at the end of the tunnel right now, and there are lots of reasons for optimism with the millions of COVID-19 vaccine doses already administered across the globe. But, as we learn more about the virus and vaccines, there are always new questions that will come up.
Dr. Steve Pomedli, League’s Chief Medical Director from Cleveland Clinic Canada, has some answers. Here are his responses to the most popular questions from League members about COVID-19 vaccines and how they could impact us in the near (and far) future.
Q: How do vaccine trials work? What does it mean when we hear that a vaccine is “95% effective?”
Vaccine trials take a number of volunteer participants — folks who are willing to try new vaccines — so that we can study how effective they are on humans. There are a few different stages. At first, we test them on a very small number of people with a primary focus on safety and making sure it doesn’t harm people.
In the second phase, we focus on making sure the vaccine creates the right “immune response reaction” and that it does what it needs to do: build immunity in your body to the intended virus.
The last phase is the biggest and can include tens of thousands of people. Everyone is separated into two groups — one group receives the vaccine and the other doesn’t. Then we follow how both groups respond and track any future medical events. In this case, the prime “event” we’re looking for would be if they contract COVID-19 or not. Between the two test groups, this gives us the data we need to see how effective the vaccine is.
Historically, vaccines have fairly different efficacy rates. Some widely-used vaccines, like for measles, mumps and rubella, are over 90% effective. Others, like for seasonal influenza, can range between 30-60% depending on the strain of the influenza virus being targeted and the vaccine’s “match” for that year’s circulating virus strains.
Importantly, even after they’re approved vaccines are also carefully studied and monitored to follow for any very rare side effects or to see if there are any longer-term safety issues. This helps us understand how effective they are in the “real world” outside of the closely controlled initial scientific studies.
Q: I’ve heard about the Pfizer, Moderna and AstraZeneca vaccines. Why are there three and how are they different?
Multiple companies around the world started working on vaccines in response to the COVID-19 pandemic, using different research and techniques. Three vaccines in particular have been most in the news, because of their promising results and have also been the first to be approved for use in countries in North America and Europe. These are from three separate pharmaceutical companies: Pfizer, Moderna and AstraZeneca.
The Pfizer and Moderna vaccines are similar in that they use a newer technology called messenger RNA or mRNA. In the case of COVID-19, this new technique looks at so-called “spike proteins” on the outside of the virus. By mimicking the virus’ genetic code using mRNA, the mRNA in the vaccine helps our body temporarily produce proteins that are similar to the virus proteins. This induces an immune response in our body to COVID-19, protecting us against future infection, but without the dangers of actually being exposed to the virus.
The great news is that so far it looks like these mRNA vaccines are relatively fast to create and have a very high efficacy rate, around 94-95%.
On the challenging side, mRNA vaccines are more expensive, less stable and need to be refrigerated at lower temperatures than we’re used to for other vaccines, which has made distribution more challenging in certain areas (like more rural or remote areas without the right infrastructure). The Pfizer vaccine has to be kept at -70 degrees Celsius or -94 degrees Fahrenheit. The Moderna vaccine has to be kept around -20 degrees Celsius or -4 degrees Fahrenheit. Fortunately, it seems that both vaccines can actually be stored for a few days at less extreme temperatures, but will begin to deteriorate after this.
The AstraZeneca vaccine isn’t mRNA-based, and uses a more traditional technique called “recombinant viral vector.” (Don’t worry, that’s as fancy as I’ll get.) This vaccine
uses a weakened version of a chimpanzee common cold virus combined with the COVID-19 genetic material to produce an immune response against the spike proteins on the outside of the COVID-19 virus.
Q: What about people who are worried about vaccine safety?
Vaccine hesitancy is always a concern. We’ll need to make sure that we think carefully about how we talk about the vaccine and give people the right information. As with any vaccine, there are questions about its safety that need to be addressed so that people feel comfortable.
Now that vaccinations have begun, confidence in them is rising in North America. Recents studies show that 60% of Americans and 60% of Canadians over the age of 12 plan to get vaccinated once it’s widely available, an increase of 10-20% from late in 2020.
This is higher than we usually see with other vaccines. No matter what, we’ll continue to closely follow the roll-out as more people are vaccinated and keep making sure that everyone who still has concerns can get access to the reliable and trusted information they need to make informed decisions.
Q: How many people need to be vaccinated for lockdowns to end?
The million-dollar question! This is rightfully top of mind for most people, but it’s a little hard to know. When it comes to the concept of herd immunity, most experts believe we’d need to see in the range of 60-80% of the population, in either the US or Canada, be vaccinated before we’d be able to safely return to a “normal” pre-COVID-19 state.
In the short term, we will have to continue with a combination of strategies. Vaccinating the most at-risk people first is critical, but we will have to continue with clear public health measures around physical distancing, wearing masks, testing and contact tracing.
I’m very excited about the potential for these new vaccines, but it could still be a long time before we hit those herd immunity vaccination thresholds. There are challenges, even with established high-efficacy vaccines like measles, with getting vaccination levels high enough to reach herd immunity.
For the COVID-19 vaccine, the complexities around distribution and global demand are proving to be another challenge. Lastly, if we do find there’s waning immunity and we need to do more frequent vaccinations than we first planned then we might not be able to administer the vaccines quickly enough to hit the total numbers we’d hope for.
Q: Have the vaccines been tested on children, pregnant or breastfeeding women, or people with compromised immune systems?
People who were pregnant or breastfeeding, or those with specific conditions causing immune system compromise, were not included in the initial trials. However, most current guidelines suggest that this should not necessarily exclude individuals in these groups from being vaccinated, especially since pregnant women or those with immune system compromise are at higher risk for more severe illness from COVID-19.
However, individuals who are in these situations should have a discussion with a medical professional to assess the benefits of the vaccine (that is, preventing potentially severe illness from COVID-19) against the potential drawbacks of not having insufficient evidence as to the safety or effectiveness of the vaccine, given their unique situation.
The initial trials didn’t include children as part of the study population. Fortunately, new trials are underway to better understand if the vaccines are safe and effective in children, including a study of the Pfizer vaccine in children ages 12-15.
Q: If you currently have or have had COVID-19, does the vaccine have any use?
The vaccine probably does still have a role for those who have or have had a confirmed COVID-19 infection. This is because there’s a fair bit of variability in the strength of the immune response to an acquired COVID-19 infection. That means that not everyone has a strong and persistent antibody response in their body, probably in part because each infection is caused by different amounts of exposure to the virus.
With that in mind, the vaccines can help deliver a standard dose and strengthen and ensure a more robust and potentially longer-lasting immune response. However, this hasn’t been fully tested so we’ll be learning more about this in the coming months.
Some guidelines have recommended waiting 3 months after a recent infection with COVID-19 before receiving the vaccine, as we know that immune protection after an acquired infection lasts at least this long. In this way, waiting for 3 months would allow those without immunity to get vaccinated first (given the current limitations on vaccine supply).
Q: I’ve heard of people getting COVID-19 multiple times. Is there still a serious risk of contracting COVID-19 even after being vaccinated?
There have been a few definite instances of people being re-infected after an initial COVID-19 infection. We have to keep in mind that our understanding of how our immune system responds to COVID-19 is still based on a relatively short period of time, at just over 1 year.
Based on what we know, and what we’ve seen of the vaccines’ efficacy so far, it looks like re-infection after vaccination would be somewhat uncommon. That being said, no vaccine is 100% effective in producing immunity, so there is always some risk of still developing a COVID-19 infection even after receiving the two vaccine doses. That being said, it does seem that the vaccines do an excellent job of protecting vaccinated individuals from severe disease though, which is really important.
We don’t have data yet that indicates that the vaccines fully protect us from carrying or transmitting the virus — known as having an “asymptomatic infection,” which can then be passed on to others who might then get sick.
Because of this, people who have been vaccinated should still follow all the same precautions, including physical distancing, wearing masks whenever near others, handwashing, and avoiding close contact especially indoors whenever possible.
Q: How did these vaccines get made so quickly? Doesn’t it usually take years?
We haven’t seen a global health threat like COVID-19 in our lifetimes, and so the widespread dedication of scientific efforts and funding to finding a vaccine is equally unique.
I think it’s really exciting to see the speed at which we’ve seen such strong results. Our governments, healthcare systems and these companies have collaborated in ways they haven’t had to before. This doesn’t mean these vaccines are less safe, it just means that because of our intense focus we were able to get them developed and approved with a much faster timeline.
There’s still a lot to learn about COVID-19 and these vaccines, but the vaccine’s high efficacy rates give us a lot to look forward to. Now the challenge is to really focus on accelerating vaccine roll-out so we can protect the most vulnerable, reduce illness, and save lives.
