History and Development of the COVID-19 Vaccine

COVID-19 Vaccination Protects You, Your Loved Ones, and the Health of Our Communities-Centre for New Immigrant Well-Being (CNIW)

Coronavirus disease 2019 (COVID-19) is caused by a virus called SARS-CoV-2, which was first found in China in December 2019. Within a few months, the virus spread quickly around the world and was declared a global pandemic.1 This led to one of the fastest vaccine development efforts in history. Vaccines were ready just one year after the first case of COVID-19 was found, but this work didn’t start from zero.2,3 

Researchers had already spent years studying other coronaviruses, including SARS-CoV-1 (which caused the SARS outbreak in 2003) and MERS-CoV (from the Middle East Respiratory Syndrome in 2012). That earlier research helped scientists understand how coronaviruses infect the body and how to fight them.3 

COVID-19 vaccines use a method called mRNA technology, which had been carefully studied and tested for decades in research on other viruses like Zika and rabies. This earlier work helped make the rapid and safe development of COVID-19 vaccines possible.4 mRNA vaccines do not contain any live virus and cannot cause infection.5 Instead, they use genetic instructions to teach the body’s immune system how to recognize a part of the virus, specifically the spike protein found on its surface, and build a strong defense against it.5

By January 2020, the genetic information of the virus had been shared globally, allowing scientists to begin developing vaccines immediately.6 The first COVID-19 vaccines, Pfizer-BioNTech and Moderna, began large clinical trials just a few months later.7,8 These trials involved tens of thousands of volunteers and were carefully reviewed by independent scientific advisory committees and national health agencies.9 Health Canada approved both of these vaccines for safe and effective public use by the end of 2020.10,11

How the COVID-19 Vaccine Works

The COVID-19 vaccine works by preparing your immune system to fight the virus before you ever get sick. When you receive an mRNA vaccine (like Pfizer or Moderna), it gives your cells instructions to make a harmless version of the spike protein. This protein cannot cause illness, but it teaches your body what the real virus looks like.4 

Once your immune system recognizes the spike protein, it responds by creating antibodies, which are proteins that stick to the spike protein and block the virus from entering your cells.4,12 Your body also creates special immune cells that remember the spike protein and stay ready to fight it in the future.4,13 

The vaccine series usually consists of two doses, spaced a few weeks apart. The first dose introduces the spike protein to your immune system. The second dose acts as a booster to build stronger and longer-lasting protection.14 After full vaccination, your immune system can respond faster and more effectively if you encounter the real virus later. This lowers the risk of severe illness, hospitalization, and spreading the virus to others.15

COVID-19 Vaccination Protects You, Your Loved Ones, and the Health of Our Communities-Centre for New Immigrant Well-Being (CNIW)

Figure 1. How mRNA COVID-19 Vaccines Work. mRNA vaccines carry instructions that help your body cells make a harmless spike protein found on the surface of the virus. This helps your immune system learn to recognize the virus and respond more quickly if you’re exposed in the future.16

Who Should Get the Vaccine?

COVID-19 vaccines are recommended for everyone aged 6 months and older. They are especially important for people over the age of 65, those with an underlying medical condition, and pregnant individuals, as these groups are more likely to get seriously ill if they catch COVID-19. Healthcare workers are also prioritized because they have a higher risk of being exposed to the virus through their daily work with patients.17

Is It Safe?

Yes, millions of people around the world, including children, teens, adults, seniors, and pregnant individuals have safely gotten the vaccine. COVID-19 vaccines have been carefully tested in large clinical trials and are still being closely watched as more people receive them.13 Health experts agree that the benefits of vaccination far outweigh the small risk of side effects.18

Are There Any Side Effects?

Some people may experience mild and temporary side effects after getting the COVID-19 vaccine. These can include soreness at the injection site, feeling tired, chills, low fever, headache, or muscle aches, all of which usually go away within hours to a few days and are normal signs that your immune system is working.19 Serious side effects, like allergic reactions, are extremely rare. If they do happen, they usually occur soon after the shot, which is why people are asked to stay at the clinic for at least 15 minutes after getting vaccinated. Healthcare workers are trained to recognize and treat these reactions quickly.19

Benefits of Vaccination During Pregnancy

COVID-19 vaccines are safe and effective at any stage of pregnancy. It is also safe for people who are breastfeeding or planning to become pregnant. Large studies involving hundreds of thousands of pregnant individuals have found no increased risk of pregnancy loss, early birth, or stillbirth after vaccination.20 Major health organizations, including the World Health Organization and the Public Health Agency of Canada, recommend COVID-19 vaccination to protect both the parent and baby.20,21

After vaccination, the parent’s body makes antibodies that fight the virus. These antibodies can pass to the baby through the placenta (the organ that connects the parent and baby during pregnancy). This gives the baby some early protection after birth, while their immune system is still developing. Antibodies can also be passed through breast milk if the parent chooses to breastfeed.20

On the other hand, getting sick with COVID-19 during pregnancy can lead to various health problems, including trouble breathing, high blood pressure, blood clots and kidney issues.22 For the baby, a serious infection during pregnancy can raise the risk of being born too early, having a low birth weight, or needing care in an intensive care unit after birth. Vaccination helps lower these risks and supports a safer, healthier start for both parent and child.20

COVID-19 Vaccination Protects You, Your Loved Ones, and the Health of Our Communities-Centre for New Immigrant Well-Being (CNIW)

Vaccination Trends in Canada

COVID-19 vaccination in Canada began on December 14, 2020. Since then, more than 100 million doses have been given.23 As of June 2024, over 80% of the population has received at least one dose of the vaccine; Newfoundland and Labrador has the highest coverage, with about 94% of people having received a dose, while Quebec has the lowest, at just under 79%.23 Vaccination rates are especially high among older adults. Coverage is over 99% among people aged 70 and older, and nearly 95% among those aged 60 to 69.23 Females are slightly more likely to be vaccinated than males. About 82.5% of females have received at least one dose, compared to 79.5% of males.23

COVID-19 Vaccination Protects You, Your Loved Ones, and the Health of Our Communities-Centre for New Immigrant Well-Being (CNIW)

Figure 2. COVID-19 Vaccine Coverage Across Canada. A cumulative percentage of the population in each province and territory who received at least one dose of a COVID-19 vaccine as of June 30, 2024.23

In the fall of 2023, Canada introduced an updated COVID-19 vaccine designed to protect against a newer XBB.1.5 Omicron variant, which had been spreading earlier that year.24 However, by the time the vaccine became widely available, the XBB.1.5 variant was already starting to decline and only made up a small number of COVID-19 cases in Canada.25 As of June 2024, approximately 18% of the Canadian population has received this updated vaccine.23 This lower uptake is partly because the virus changes so quickly, which makes it harder to develop vaccines in time. By the time a new vaccine is ready, the version of the virus it was made for may no longer be spreading widely.25

Gaps and Disparities in Vaccine Uptake

Although Canada has achieved high overall COVID-19 vaccine coverage, some groups still face barriers to getting vaccinated. These include not having enough time or transportation to reach a clinic, or finding it hard to use online booking systems.26 The COVID-19 Vaccination Coverage Survey (CVCS) found that people with lower incomes (under $60,000), lower levels of education, and those living in small or rural communities were less likely to be vaccinated.26

Studies from the United Kingdom and the United States also show that people from racialized or ethnic minority communities often have lower vaccine uptake. One major reason is medical mistrust, which can come from past negative experiences with the healthcare system and cause fear or doubt about vaccine safety.27 In Canada, some immigrant communities also have lower vaccination rates due to language barriers and a lack of clear, reliable information in their preferred language.28 Misinformation shared on social media or within communities can further increase confusion and create more doubt about how safe or effective the vaccine really is.29

To help address these issues, public health teams have worked with local community leaders to create campaigns in multiple languages and provide mobile vaccine clinics that bring vaccines directly into neighborhoods. This makes it easier for people to get vaccinated without needing to travel far or take time off work.30,31 Research also shows that healthcare providers are among the most trusted sources of vaccine information, and that people are more likely to get vaccinated when their provider gives them a strong recommendation.32

Conclusion

Even though the COVID-19 pandemic is not as severe as it once was, the virus has not gone away. People continue to get sick, and new variants can still appear and spread. Staying up to date with your COVID-19 vaccines is a simple and effective way to protect your health and lowers the chance of passing the virus to others in your community, especially those with weaker immune systems. As life moves forward, vaccines remain one of our strongest tools. Getting vaccinated is not just a personal decision, but a shared effort to keep our communities healthier, safer, and better prepared for whatever comes next.

References

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  1. Center for Global Development. (2022). The COVID-19 Vaccine Rollout Was the Fastest in Global History, but Low-Income Countries Were Left Behind. https://www.cgdev.org/blog/covid-19-vaccine-rollout-was-fastest-global-history-low-income-countries-were-left-behind. Accessed July 22, 2025.
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  1. World Health Organization. (2022). Statement for healthcare professionals: How COVID-19 vaccines are regulated for safety and effectiveness. https://www.who.int/news/item/17-05-2022-statement-for-healthcare-professionals-how-covid-19-vaccines-are-regulated-for-safety-and-effectiveness. Accessed July 22, 2025.
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  1. Health Canada (2020). Health Canada authorizes Moderna COVID-19 vaccine. https://www.canada.ca/en/health-canada/news/2020/12/health-canada-authorizes-moderna-covid-19-vaccine.html. Accessed July 22, 2025.
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By: Lisa Fang