Most experts think that the only way out of the Covid-19 Pandemic is a vaccine of which there are currently 165 in development. Ready or not, someday soon, you will have to make a decision about whether to get one of these vaccines. Will you have the knowledge and understanding to make that decision when that time comes? I certainly hope so and maybe I can help. Stay tuned while and Sonya and I get you up to speed with SARS-CoV-2 vaccine knowledge circa August 2020.
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Science Drive-How Do Viruses Infect Cells?
Before you can understand how a vaccine might work, we need to review briefly how viruses infect their hosts, the child or adult that they wish to use to reproduce. Remember, viruses are parasites, using the people they infect to make copies of themselves before moving onto another victim. The SARS-CoV-2 virus is thought to enter human lining cells of the nose and lungs by attaching its spike protein to receptors on the cell surface -the so called ACE 2 receptors. Once the virus has gained entry into the cytoplasm of the cell, the body of the cell, its RNA genetic material is released and takes over the cell machinery and starts making new copies of itself. Once finished with that cell, onto being released from that cell and infecting other cells in its host etc. etc. As you can see, the virus’ own RNA serves as the blueprint to hijack the cell into making copies of itself. The virus is going “viral” as we like to say. In order to stop this process from, researchers need to figure out how to stop the virus by doing two things; making “neutralizing antibodies” that block the virus’s ability to enter the cell and by activating killer T cells that can destroy already infected cells before they can make viral copies and keep the infection going.
What Would The Perfect Vaccine Look Like?
Let’s start this discussion with imagining what the perfect Covid-19 vaccine would look like? If such a thing could be crafted, what properties would it have? First and foremost, the perfect Covid-19 vaccine would be effective, 100% effective, protecting everyone who gets the shot. It would also need to ensure that those who get the vaccine, will have long-term immunity against the virus. What is long-term you ask, let’s say as long as the natural infection protects from reinfection-probably about 2 years. This perfect Covid-19 vaccine also needs to have no serious side effects other than nuisance minor inconveniences like a sore arm or feeling mildly ill briefly. Of course, our perfect Covid-19 vaccine would need to protect people from the natural circulating germ and not heighten their chance of having an exaggerated infection if they should encounter the wild-type germ. Unfortunately, this has happened with previous attempts to create other viral vaccines – RSV and Dengue being the most dramatic examples. And finally, this perfect Covid-19 vaccine would need to be manufactured quickly, be widely accepted, and be inexpensive enough or free for everyone to be able to afford it.
If we could make this perfect vaccine for COVID-19 and get it widely distributed, it would mean widespread immunity – the answer to the current health crisis we’re in. So why don’t we have one now? For one thing, vaccines have historically taken 10-15 years to create. The fact that there are phase III trials in people happening right now after only 5 months of knowing about this virus is unheard of. This is science at breakneck speed! Currently, it does look like we will have an effective vaccine but I hate to break the news to you… it certainly won’t be the perfect vaccine that we just described, but hopefully it will be something close.
SARS-CoV-2 Vaccine Basics
Even if you haven’t been reading extensively about the SARS-CoV-2 virus, you have undoubtedly seen drawings and representations of what the virus looks like, with those ugly spikes sticking out all over the virus. At the end of each of those spikes is a protein called for lack of a better term, the “spike protein”. It is this spike protein that allows the SARS-CoV-2 virus to infect its host. The thinking is, prevent the spike protein attachment to our cells, and you stop the infection before it ever gets started ! To our knowledge, all of the 165 vaccines in development all with the goal of neutralizing the spike protein-producing the magical “neutralizing antibodies” need to stop infection.
While the goal of all the vaccines are the same, get the patient to destroy the SARS-CoV-2 virus before it can infect anyone, the way these vaccines go about this are all a little different. There are currently 26 vaccine candidates in clinical trial that are getting close. Remember, vaccines work differently than therapies for infected people. For the purposes of this discussion, we are going to define a vaccine as something that simulates the natural infection, not passive therapies like convalescent serum, monoclonal antibodies, immune modulators, or antiviral medications. But how do these vaccines work? In a nutshell, they fall into a few categories- whole virus vaccines, nucleic acid vaccines (gene based), and viral vector vaccines. Let’s take them one a t a time.
Whole virus vaccines are the most common type of vaccine, which works by giving people a weakened version of the virus, either live or killed. These weakened vaccine strains of the virus, allows the vaccinated person’s immune system to gear up and provide antibodies and other defenses against the microbe. Your annual flu shot is a good example of this. The virus is grown in a way that forces it to lose most of its disease producing properties but retain enough of the look of the original disease-causing virus that it imparts immunity to those vaccinated. Think measles, chickenpox, flu, and polio. This is very old vaccine technology, going back 100 years. These vaccines are slow to produce but do work. for many diseases.
Nucleic Acid Vaccines are another approach being tried against SARS-CoV-2. As we talked about before, the SARS-CoV-2 virus introduces its genes (its RNA) into the cytoplasm of the host cell and takes over the machinery of the cell to reproduce itself. Very ingenious but what if, a vaccine genome was introduced before the natural infection had a chance to occur and instead of directing the cell to make new virus, directed the cell to produce spike proteins and other viral proteins galore. All this loose spike protein, which the host would see as foreign, could trigger an immune response before infection ever happened! The goal is to have the host produce neutralizing antibodies to the virus without ever being infected. It turns out that three of the top vaccines in development do exactly this, by introducing either manufactured RNA, messenger RNA, or even DNA, all with instructions to produce spike protein. Each of these vaccines use ingenious ways of getting the new vaccine genes into cells but all have the same goal- get the vaccinated person to recognize the SARS-CoV-2 as foreign and learn how to destroy it. A vaccine allows our bodies to make those antibodies and remember the virus without us ever getting sick and having all the awful symptoms.
Viral Vector Vaccines are another technology being tried in the race to stop the pandemic of Covid-19. The leading vaccine candidate uses an adenovirus to deliver the spike protein directly, not genetic instructions like the nucleic acid vaccines we just talked about. Once the spike protein is presented to the vaccinated person, their immune system kicks in to become activated toward the SARS-CoV-2 virus. I know you are thinking, prevent a viral infection by giving someone a viral infection? Does that make any sense? Well, it’s good to know that the adenovirus this vaccine uses does not have the ability to replicate, and thus cannot cause disease in the person being immunized.
I’ve tried to simplify a very complex subject and give you a foundation to understand the barrage of information you are going to encounter in the coming months as decisions need to be made about your family’s health. Let’s hope that our scientists and government officials are up to the task of delivering us a vaccine that will loosen the grip that Covid-19 has on all of us, especially our children. But before we leave this subject, let me muddy the waters by introducing some other issues that revolve around any vaccine you would consider getting for you and your family.
Other Questions Revolving Around a Vaccine for Covid-19
- Will SARS-CoV-2 be like Influenza, Needing Yearly Infections? At this point experts are unsure but may feel that in the future, we will be getting our seasonal “corona shot” along with our seasonal “flu shot”. Although COVID-19 does not mutate or change as quickly as the common flu, a natural infection and likely vaccine immunity likely will fail to produce long term immunity against the germ. As a result, it is very possible that we will need annual shots to protect children and adults. Time will tell.
- Can a person get Covid-19 twice? You may have heard stories or read articles about people being sick with Covid-19, clearing the infection, and then testing positive again as if they were reinfected with corona virus. So, is it possible to have Covid-19 twice? The short answer is that it’s unlikely, but we don’t actually know. A lot is uncertain about corona virus and there is anecdotal evidence of patients getting reinfected. False positives from testing could also be a cause of this. The bottom line is that we don’t know and we should be paying attention to the research as it becomes available to us.
- Would the world be better off just waiting for herd immunity to occur? Herd immunity is when a large percentage of a population has antibodies/immunity against a virus, thereby protecting the population from the spread of the virus. Vaccines help establish herd immunity, protecting the small population of people who are immunocompromised or unable to have vaccines for medical reasons. This is why getting your vaccinations is so important. Waiting for herd immunity against COVID-19 rather than developing a vaccine would cause significantly more deaths. Watching literally millions of our fellow citizens die while herd or community immunity stops it is just not ethical or an option in our view.
- Can we trust the science and manufacturing of this vaccine? Labs in China and Russia are racing toward the development of a vaccine, and possibly sidestepping the typical safety precautions to get to a vaccine first. Unfortunately, the vaccine industry in China specifically also has a past of safety scandals and problems with efficacy. The world has good reason not be so trusting of vaccines produced in China. Before we vaccinate literally billions of people, we need to ensure that we are meeting safety standards and not putting people at risk. Safety, efficacy, and public trust are all extremely important. It is very unlikely that an unsafe vaccine will be allowed in the United States, but we do have to be patient and take the necessary precautions as it’s developed.
- Will a Covid-19 Vaccine Inadvertently Make Covid-19 Worse?- As I mentioned earlier, some vaccines developed in the past have, rather than prevent the natural infection, actually intensified and worsened the infection for the person who has been vaccinated- definitely not what was intended. Whether this will happen with any of these vaccines remains to be seen.
Scientists around the world are racing to answer these and many other questions about SARS-CoV-2 and the disease it causes, Covid-19. Amazing progress is being made every day. I am confident that we will eventually stop most of the disease and death that this germ has brought on us.
A Few Final Reminders
Before I sign off for the day, I have a few final reminders for you and your family. You’ve heard them before, but my priority is keeping you safe and informed. We’ve been struggling our way through this pandemic for months now, but COVID-19 is not going away until we have all become immune, either through herd immunity or a vaccine. Until then, we need to stay vigilant! Remember to keep your distance from others as much as possible. When you go outside of your home, wear your mask. Keep washing your hands as much as possible. I also like to keep hand sanitizer in my car as a quick fix after the grocery store or other essential outings. And importantly, if you feel sick at all, stay home and call your healthcare provider for advice! Even if you don’t think you were exposed or you still feel like you can function, keep others safe by taking care of yourself and resting at home. The only way to get through these crazy times is to look out for ourselves and for others. We will get through this.
Well, I hope that helps bring your knowledge up to speed about SARS-CoV-2 vaccines. If you value the information you get from Portable Practical Pediatrics, consider liking and sharing content you hear on our site. Positive reviews are also helpful. This is Dr. Paul Smolen, broadcasting from studio 1E, hoping that scientists can really lean, on Covid-19. Until next time.
Many thanks to Drs. Monica Miller and Charlotte Rouchouze for their help in the writing of this pedcast.