What we know so far about COVID-19 vaccines and immunity

The COVID-19 vaccine will be administered to people across the country in the coming months. Since COVID-19 is a new virus, some questions about how the vaccine works are still being answered by the scientific community. Here’s what we know so far about the COVID-19 vaccine when it comes to immunity.

What is immunity?

Your immune system is an intricate network of organs, tissues, and cells that work together to fight off pathogens — the bacteria, viruses, and microorganisms that cause disease. 

When you’re infected with a virus like COVID-19, it takes over healthy cells in your body. The virus has proteins on the outside called antigens, and when they’re detected by your immune system, they trigger your immune response. Your immune response is your body’s way of neutralizing disease.

One part of your immune response is the production of antibodies. Antibodies are y-shaped proteins that lock onto the virus antigens and help destroy them. The fewer infected cells in your system, the less strength the virus has to make you sick or spread a disease to others. 

Once your body destroys the infected cells, your immune system memorizes the steps it took to do so. If the same disease-causing agent enters your body again, your immune system uses its memory to identify, attack, and destroy it. 

Each pathogen has unique antigens, which means no two illnesses are destroyed by the same type of antibody. That’s why antibody development can take time. 

Once your body remembers how to identify and fight a pathogen, you start to recover faster if you’re exposed to it again. In some cases, your body becomes so effective that you don’t get sick at all. When your immune system is able to destroy a pathogen before it makes you sick, you have immunity.

What are vaccines and how do they work?

Vaccines typically contain weakened or inactive samples of a pathogen’s antigen. In other words, vaccines are harmless samples of a disease. It may seem counterintuitive to intentionally expose yourself to a harmful organism, but vaccines are vetted for safety before they’re approved for use. COVID-19 vaccines will go through extensive trials. 

Vaccines are generally administered via injection. Oral and nasal vaccines also exist, though the COVID-19 vaccines likely won’t rely on these methods. Vaccines cause your body to react as if it were fighting a real infection. Your immune system learns to neutralize the pathogen so that you’re better prepared to defeat it later if exposed.

In some cases, one vaccination is enough for your body to remember how to neutralize a harmful organism. With other diseases, multiple doses need to be administered before the body learns how to defend itself. That’s why some vaccinations require booster shots. Some COVID-19 vaccines will require two doses.

Some people with compromised immune systems may not be good candidates for certain vaccines. Exposure to pathogens is risky because their body has trouble fending off disease. People with HIV or who have undergone chemotherapy may be in this category.

Those with compromised immune systems can still benefit from widespread vaccination in their community. When enough people in close proximity are vaccinated, it’s harder for a contagious disease to spread. This is called herd immunity, or community immunity. It’s a form of protection for people who can’t get vaccinated, since they’re less likely to come in contact with someone who’s sick. 

Immunity and COVID-19

With other pandemics like H1N1, which is a strain of the flu virus, it was easier to create a vaccine and understand how immunity works. That’s because similar flu viruses are known to scientists, and flu shots are given to the public every fall. That made it easier to come up with a vaccine fast, since there were already models approved by Health Canada.

Unlike the flu virus, there’s never been a widely distributed vaccine for coronaviruses before. Plus, because COVID-19 is brand new, so there’s a lot we’re still discovering about how the virus affects us.

When it comes to COVID-19 and immunity, a few questions are still being researched:

Can you still get COVID-19 if you’ve been vaccinated?

There are many COVID-19 vaccines in development. Different vaccines have different rates of efficacy. That means some vaccines don’t work 100% of the time, so it’s possible for someone who has received a vaccination to still contract COVID-19. One front-runner vaccine reported 94% protection. That means there’s a 6% chance that someone vaccinated with that vaccine will still get COVID-19.

Even though vaccines aren’t perfect, it’s generally accepted that getting vaccinated poses less danger of health complications than getting sick from a disease.

If you get the COVID-19 vaccination, are you immune for life?

We don’t know yet. Research so far indicates that some people who’ve had COVID-19 have shown resistance to reinfection. How long that resistance lasts is still unconfirmed.

If you’ve had COVID-19 already, are you immune?

No human trials have been done to see if someone who has had COVID-19 can get it again. Research suggests that reinfection is unlikely.

We’re in the early stages of understanding how COVID-19 impacts our immune systems. Different vaccines are being created by countries around the world. Once a vaccine has been approved in Canada, we’ll have more information on what to expect.