Over the past several months, scientists have gathered knowledge that will help us treat COVID-19, find an effective vaccine and get us all back to work, school or spending time with friends and family. This article will provide an overview of the progress made so far, however, it’s important to note that the science supporting this article is constantly evolving and can change on a regular basis.
How does SARS-CoV-2 (the virus that causes COVID-19) spread between humans?
People are viral Airbnb hosts. Viruses, like SARS-CoV-2, live, replicate and spread by getting inside a host through the eyes, nose or mouth – then invading the host’s cells where they multiply and cause illness. This is why we’ve been told to constantly wash our hands and keep them away from our face. Viruses can live on hard surfaces such as door knobs or elevator buttons for hours or even a few days. Those frequently touched surfaces are the major means of transferring the virus between people.
Physical distancing also helps prevent the spread of infection because a cough or a sneeze can propel the virus several feet, potentially infecting someone nearby. The virus disperses quickly in the air and rapidly drops to the ground, but when it drops onto a hard surface and someone touches it, they can transfer it to their face and may be infected.
We know that some people get sick from this virus while others have been infected but remain asymptomatic or have very mild symptoms, yet they can still spread the virus.
What does “viral mutation” mean?
One feature that makes viruses particularly nasty is their ability to mutate or change characteristics. Mutations allow viruses to move to new hosts, for instance between different kinds of animals or from animals to people. Understanding how a virus mutates and how quickly a virus mutates can be used by scientists to determine where a virus originated and how it spread.
It’s essential to understand the speed at which a virus mutates (called the mutation rate) because that contributes to its virulence (how dangerous it is) and can help in the development of treatments and vaccines. Viruses with high mutation rates, including hepatitis B and C and HIV, tend to be chronic, are more difficult to treat and are less likely to be controlled with a vaccine. Thankfully, SARS-CoV-2 doesn’t have a high mutation rate, so eventually a vaccine will likely help stop its spread.
Why don’t we have a treatment for COVID-19?
SARS-CoV-2 isn’t the only coronavirus that has proven deadly for humans. SARS-CoV killed hundreds of people in 2003 and many treatments were under development when that virus was finally contained.
Once contained, drug development wasn’t urgently required, but research into coronaviruses continued. Unfortunately, mostly due to lack of funding, no drugs were developed based on that research. SARS CoV and SARS-CoV-2 share about 90 per cent of their genetic material, so scientists are reviewing previous research and using that information to develop targets for drug treatment.
Right now, there are probably hundreds of different medications at various stages of development. All must be rigorously tested to make sure they work and are safe, followed by a lengthy review process by federal regulators (e.g. Health Canada) before any are available to Canadians. Usually, it takes a decade or more to bring a new medication to market. However, given the urgency and massive world-wide impact of COVID-19, competitors are working together and sharing research, which will likely shorten the time to develop an effective treatment.
What are antibodies and why is it helpful to measure them?
Antibodies, also called immunoglobulins (Ig), are proteins we make to fight off pathogens such as bacteria or viruses. Antibodies are developed specifically for each pathogen, so if you get sick with COVID-19, you will make specific antibodies to neutralize the SARS-CoV2 virus only.
Two specific types of antibodies you’ll be hearing much more about are IgM and IgG. IgM antibodies are produced soon after a pathogen invades our body. There’s only a small amount of IgM produced, but it sounds the alarm, rallying the immune system troops and telling the body there’s a sinister threat that has breached our outer defenses. IgG is more abundant and lethal to pathogens by identifying them as foreign invaders and neutralizing them.
A serology test is done to determine if you have antibodies in your blood for a specific pathogen. If you’ve recently been infected by SARS-CoV2, you would have developed specific IgM and/or IgG antibodies. For most coronaviruses, once you’ve developed IgG antibodies, you are immune. However, for SARS-CoV-2, we don’t know for certain how effective those antibodies are at preventing reinfection and how long the immunity will last.
It’s useful to test for SARS-CoV-2 antibodies to know whether someone has previously been infected since a large percentage of infected individuals have very mild or no symptoms. Once we understand how effective the antibodies are at preventing reinfection and how long those antibodies last, it will help us get people back to their usual activities and keep those who remain vulnerable to the infection safe.
What is herd immunity?
Herd immunity occurs when enough people become immune to an infectious disease that it is no longer spreading in a community. This happens when many people in a community get infected and develop immunity to a pathogen naturally or through mass vaccination.
Many people rely on herd immunity to keep them safe. People who are immunocompromised due to certain illnesses or treatments, like chemotherapy for cancer, are unable to make sufficient antibodies to protect themselves from infectious diseases. Likewise, babies, young children, pregnant women and the elderly are more vulnerable to infectious diseases due to an immature or less effective immune system.
We are a long way away from reaching the number of infected individuals necessary to reach herd immunity for SARS-CoV-2. Even in areas with the highest rates of community spread, most estimates suggest that less than 20 per cent of individuals have been infected with the virus. In order to reach herd immunity, most viruses require at least 80 per cent of the community to be immune. This means the world needs a vaccine to make enough people immune to SARS-CoV-2 in order to stop the spread.
How are vaccines created and why does it take so long?
There are several different kinds of vaccines, but they all work in basically the same way: they provoke an immune response that protects an individual from getting sick. If enough people in a population are vaccinated, that can provoke herd immunity and stop the pathogen from spreading in a community.
Vaccines can be “live attenuated,” meaning they contain a tiny amount of the live virus, enough to provoke the development of antibodies but not enough to cause illness. A vaccine can also contain an inactivated piece of a virus, which again is able to provoke antibody production. Although safer to produce, inactivated vaccines are not as strong and often require multiple doses and boosters.
Now, we also have genetically engineered vaccines, which contain a piece of the pathogen’s genetic code. These vaccines cause the body to make antibodies, targeting any invader that has that genetic code, so perhaps we will eventually have a vaccine that targets every coronavirus since they all share a great deal of genetic material.
Vaccines can take decades to develop and cost billions of dollars. However, scientific innovation, especially related to our understanding of genetics, has led to more rapid vaccine development, which potentially, for COVID-19, means we could have a vaccine within a year. Despite the urgency to find a vaccine, it’s still necessary to ensure it’s not only effective, but safe.
Finally, no vaccine will be useful if it’s not used widely, which will make finding our way to the other side of this pandemic more challenging.