COVID-19 Vaccines: A Comprehensive Guide


Historically, vaccine development has been a prolonged process, often taking years if not decades. However, with COVID-19, using platforms like mRNA technology, vector vaccines, and protein subunit vaccines, several viable candidates were designed within mere months of the virus’s genetic sequence becoming available.

Steps in vaccine development

  • Preclinical Testing: Researchers test the vaccine on cells and then on animals to see its efficacy and safety.
  • Phase I Trials: The vaccine is given to a small number of people to gauge safety and dosage.
  • Phase II Trials: Vaccines are administered to hundreds of people, usually including those of different ages and health statuses, to see their safety and ability to stimulate the immune system.
  • Phase III Trials: Thousands of participants are involved, and the vaccine’s ability to prevent the disease is observed.
  • Approval: Regulating entities like the FDA, EMA, and WHO review the trial results and decide on emergency use or full approval.

For COVID-19, many of these steps overlapped, allowing for expedited development without compromising on the stringent safety and efficacy criteria. The Food and Drug Administration allowed an Early Use Authorization (EUA) for COVID-19 Vaccines. In a groundbreaking global effort, the scientific community rapidly developed, tested, and distributed vaccines against COVID-19.

The table below summarizes the timeline of rapid development and approval of all COVID-19 vaccines:

Vaccine Type Brand Name FDA Approval Dates
Pfizer-BioNTech mRNA Comirnaty December 11, 2020
Moderna mRNA Spikevax December 18, 2020
Johnson & Johnson Viral vector Janssen February 27, 2021
Novavax Protein-based Nuvaxovid June 23, 2022

How COVID-19 Vaccines Work

COVID-19 vaccines are a safe and effective way to protect yourself from the coronavirus disease 2019 (COVID-19). COVID-19 vaccines work by priming the body’s immune system to fight the virus.

When you get a COVID-19 vaccine, the vaccine teaches your body’s immune system to recognize and fight the virus. The vaccine does this by exposing your body to a harmless version of the virus or its proteins.

Once your body’s immune system has been exposed to the virus or its proteins, it will start to make antibodies. Antibodies are proteins that bind to the virus and help to destroy it.

If you are later exposed to the virus, your body’s immune system will be ready to fight it off. The antibodies will bind to the virus and prevent it from infecting your cells.

Types of COVID-19 Vaccines

There are currently three types of COVID-19 vaccines available in the United States:

  • mRNA vaccines: These vaccines instruct cells to produce a protein resembling the spike protein on the SARS-CoV-2 virus surface, facilitating immune system recognition. The spike protein is what the virus uses to enter cells.
  • Viral vector vaccines: These vaccines use a weakened or inactive virus to deliver genetic material into your cells. This genetic material prompts your cells to produce the spike protein .
  • Protein subunit vaccines: These vaccines contain a piece of the spike protein that has been made in a lab. The spike protein is then injected into your body.

A fourth type of COVID-19 vaccine made with an inactivated COVID-19 virus was used in other countries. Inactivated virus vaccines use a virus that has been killed to stimulate the body’s immune response.

Vaccine Type Brand Name Approval Dates
Sinovac Inactivated virus CoronaVac December 17, 2021
Sinopharm Inactivated virus BIBP-CorV December 20, 2021

All types of COVID-19 vaccines have been extensively studied and vigorously tested in clinical trials. They are shown to be effective and safe for people of all ages. The duration of protection provided by COVID-19 vaccines is not yet known. However, some studies have shown that the protection can last for several months.

Everyone 5 years of age and older should get a COVID-19 vaccine. This includes people who are healthy as well as people with underlying health conditions. Studies have shown that COVID-19 vaccines are also safe and effective for pregnant and breastfeeding women and their babies. It reduces the risk of serious illness, hospitalization, and death from COVID-19 in all populations. 

If you have any questions or concerns about getting a COVID-19 vaccine, talk to your doctor.

These vaccines prevent serious illness, hospitalization, and death from COVID-19. They are also effective at preventing the spread of the contagious virus.

COVID-19 Storage & Refrigeration

COVID-19 vaccines must be stored and handled carefully to maintain their potency. The specific storage requirements vary by vaccine, but they generally require storage in a refrigerator or freezer.  Here is a table summarizing this information:

Vaccine Brand Name Storage Temperature
Pfizer-BioNTech Comirnaty -70°C to -60°C (-94°F to -76°F)
Moderna Spikevax -20°C to -15°C (-4°F to 5°F)
Johnson & Johnson Janssen 2°C to 8°C (36°F to 46°F)
Novavax Nuvaxovid 2°C to 8°C (36°F to 46°F)
Sinovac CoronaVac 2°C to 8°C (36°F to 46°F)
Sinopharm BIBP-CorV 2°C to 8°C (36°F to 46°F)

Once the vaccines are removed from the refrigerator or freezer, they must be thawed and used within a certain period of time. The Pfizer-BioNTech vaccine can be thawed at room temperature for up to 6 hours, while the Moderna vaccine can be thawed in a refrigerator for up to 30 hours.

The vaccines have to be handled with care to avoid contamination. They should not be shaken or frozen, and direct sunlight and heat have to be avoided.

Before administering the vaccine, the healthcare provider should check the expiration date and visually inspect the vial for any signs of contamination. The vaccine should be administered immediately after thawing.

It is important to follow the manufacturer’s instructions for the storage, distribution, handling, refrigeration, and thawing of COVID-19 vaccines to ensure their effectiveness.

Effectiveness And Efficacy of COVID-19 Vaccines

Efficacy of COVID-19 vaccines was measured in clinical trials, comparing a vaccine group to a placebo group. 

Effectiveness is measured in real-world studies, where participants are not randomly assigned to groups. The effectiveness rate is calculated by comparing the number of people who get sick in the vaccinated group to the number of people who get sick in the unvaccinated group.

The efficacy and effectiveness rates of vaccines can change over time, as the virus mutates and the immune system’s response to the vaccine wanes. Other factors, such as age, underlying health conditions, and the timing of vaccination, can also affect the efficacy and effectiveness of vaccines.

The effectiveness and efficacy of all types of COVID-19 vaccines is summarized below:

Vaccine Efficacy (clinical trials) Effectiveness (real-world studies)
Pfizer-BioNTech 95% 91% against symptomatic infection, 95% against hospitalization, 97% against death
Moderna 94.10% 93% against symptomatic infection, 96% against hospitalization, 98% against death
AstraZeneca 76% 67% against symptomatic infection, 82% against hospitalization, 92% against death
Johnson & Johnson 66% 70% against symptomatic infection, 80% against hospitalization, 86% against death
Novavax 90% 80% against symptomatic infection, 90% against hospitalization, 95% against death
Sinopharm 79% 72% against symptomatic infection, 86% against hospitalization, 91% against death
Sinovac 50.40% 50.3% against symptomatic infection, 67% against hospitalization, 80% against death

COVID-19 vaccines are necessary to protect yourself from COVID-19 and to help prevent the spread of the virus. The benefits of getting COVID-19 vaccines include protection from serious illness, hospitalization, and death from COVID-19.

COVID-19 vaccines are safe and have been rigorously tested in clinical trials. They are effective in preventing the spread of the contagious virus. They may not be 100% protective but they help prevent serious illness, hospitalization, and death from COVID-19.

Side Effects of COVID-19 Vaccines

The most common side effects of COVID-19 vaccines are mild and go away on their own within a few days. These side effects may include pain, redness, and swelling at the injection site, fatigue, headache, muscle pain, chills, fever, and nausea.

Serious side effects from COVID-19 vaccines are very rare

COVID-19 vaccines are accessible at:

  • Doctor’s offices
  • Pharmacies
  • Community health centers
  • Vaccination clinics

The CDC website provides a list of nearby vaccination locations.


These vaccines have showcased what collaboration amongst the scientific community, the Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC) can achieve. Overall, there was a reduction in COVID cases, protection against new variants, the development of herd immunity as well as the prevention of a long COVID syndrome. 

These vaccines helped economic and social rejuvenation by allowing the easing of restrictions. Pockets of challenges in vaccine hesitancy, global distribution, and the emergence of new variants still remain and are being worked upon.


  • How long do COVID-19 vaccines last?

It is not yet known how long COVID-19 vaccines last. However, studies have shown that the protection can last for at least 6 months. Some studies have even shown that the protection can last for up to a year.

  • Can I still get COVID-19 after being vaccinated?

Yes, it is possible to still get COVID-19 after being vaccinated. However, the vaccine is very effective at preventing serious illness, hospitalization, and death from COVID-19. Even if you do get COVID-19 after being vaccinated, you are likely to have a much milder case of the disease.

  • Are COVID-19 vaccines safe for pregnant and breastfeeding women?

Yes, COVID-19 vaccines are safe for pregnant and breastfeeding women. Studies have shown that the vaccines are effective at protecting pregnant and breastfeeding women from COVID-19, and they do not harm the baby.

  • Can I mix and match COVID-19 vaccines?

Yes, it is safe to mix and match COVID-19 vaccines. Studies have shown that mixing and matching COVID-19 vaccines is just as safe and effective as getting two doses of the same vaccine.

  • What are the side effects of COVID-19 vaccines?

The most common side effects of COVID-19 vaccines are mild and go away on their own within a few days. These side effects can include:

  • Pain, redness, and swelling at the injection site
  • Fatigue
  • Headache
  • Muscle pain
  • Chills
  • Fever
  • Nausea

Rare side effects have also been reported, such as myocarditis (inflammation of the heart muscle) and pericarditis (inflammation of the lining around the heart). However, these side effects are extremely rare, and the benefits of the vaccine far outweigh the risks.

Keep you and your loved ones safe from COVID-19. Get vaccinated nao!

Disclaimer: The information presented in this article is intended for general informational purposes only and should not be considered, construed or interpreted as legal or professional advice, guidance or opinion.

Book an appointment with one of our therapists today.

Keep you and your loved ones safe from COVID-19. Get vaccinated nao!