Kaiser Permanente | March 31, 2021

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COVID-19 vaccines were developed safely
The first COVID-19 vaccines began rolling out less than a year into the pandemic. Vaccine development typically takes much longer, so it’s easy to wonder how we got these vaccines so soon. But the COVID-19 vaccines have been held to the same safety standards as any other vaccine — and rigorous clinical trials have proven that they’re safe and effective.  

The accelerated COVID-19 vaccine timeline
Each COVID-19 vaccine went through the same process as any other vaccine — only faster.

The accelerated COVID-19 vaccine timeline graphic

The public health emergency fast-tracked vaccine development
We knew early on that COVID-19 was extremely serious and spreading fast. The world needed a safe, effective vaccine as soon as possible. Here’s how we did it:

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Unprecedented funding
The government spared no expense responding to COVID-19. The time, money, and resources dedicated to making vaccines meant multiple steps could happen at once — instead of one at a time. 

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Established research
COVID-19 vaccines are new, but the technology behind them is not. Research to develop new vaccines designed to address serious pandemic situations like COVID-19 has been underway for decades. So when the COVID-19 pandemic hit, scientists were able to put those technologies into practice fast, tailor them to protect against the specific virus we’re trying to fight, and develop COVID-19 vaccines more efficiently.

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Widespread collaboration
Groups of scientists and medical experts around the world recognized the need to work together to create vaccines quickly. Joining forces and sharing resources helped everyone accomplish more in less time.

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High numbers of research volunteers
The public was well-aware of the dangers of COVID-19. Finding clinical trial volunteers is usually a challenge, but this time researchers had a robust sample size almost immediately.

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Early results
Because COVID-19 was spreading so fast, it didn’t take long for researchers to prove that the vaccines were preventing infection. While widespread exposure is never a good thing, we had robust data about safety and effectiveness much faster than usual.

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Front-end manufacturing
Vaccine manufacturers typically don’t start planning for production until clinical trials are complete. With the pandemic surging, they scaled up earlier so vaccines could be produced as soon as they got approved.


Data proves COVID-19 vaccines are safe and effective
No vaccine is 100% effective — and they don’t need to be 100% effective to save lives. Clinical trials showed both the Pfizer and Moderna vaccines are more than 94% effective in protecting against COVID-19.1,2 And the vaccine developed by Janssen, a Johnson & Johnson company, is 85% effective in preventing severe cases of COVID-19.3

To help put these numbers in perspective, seasonal flu vaccines are only 40% to 60% effective — but flu vaccinations prevented an estimated 7.52 million illnesses, 105,000 hospitalizations, and 6,300 deaths during the 2019–2020 flu season alone.4,5 All 3 of the COVID-19 vaccines have even higher efficacy rates — so imagine how many illnesses, hospitalizations, and deaths they’ll prevent.

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COVID-19 vaccine safety and effectiveness data is open to the public
All the data published by the Food and Drug Administration (FDA) is posted online and open for everyone to review. You can see exactly how the vaccines work — and why we know they’re safe:


COVID-19 vaccine side effects are usually minor and manageable 
Like most vaccines, the ones for COVID-19 can produce side effects. These side effects are normal signs that the body is building immunity, and may include:

  • Pain at the injection site 
  • Fatigue 
  • Headache 
  • Muscle pain 
  • Chills 
  • Joint pain 
  • Fever 

It’s important to remember that all vaccines carry risks for side effects. These risks must be balanced with the benefits. COVID-19 is a serious illness — and anyone can develop life-threatening complications if they get it. Fortunately, the FDA has confirmed that the benefits of the COVID-19 vaccines outweigh any risks for possible side effects.


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Specific vaccine concerns and considerations
Although extremely rare, allergic reactions can occur. If you have a history of severe allergic reactions or carry an epinephrine injector (such as an EpiPen), please talk to your doctor before getting a vaccination.6 You shouldn’t get vaccinated if you’ve ever had an immediate allergic reaction to any of the ingredients in the vaccine. And you shouldn’t get a second dose if you had a severe allergic reaction after your first dose.

For more information about COVID-19 vaccines for people with allergies, please visit the Centers for Disease Control and Prevention website. If you have questions or concerns about allergies or any other health conditions, your doctor can help you decide if getting vaccinated is the right choice for you.

You can’t get COVID-19 from the vaccine
Vaccination triggers a natural response where the body generates its own protection against a virus. COVID-19 vaccines don’t introduce the virus into the body at all. Instead, they teach your body how to recognize the coronavirus and create antibodies to fight it. Since no trace of the coronavirus was used to create the COVID-19 vaccines, it’s impossible for them to make you sick with COVID-19.

We recommend getting the COVID-19 vaccine when it’s available to you
Choosing to get vaccinated — and following COVID-19 safety guidelines until medical experts say it’s safe to stop — are the best things you can do to protect yourself and your loved ones against COVID-19. The sooner people get vaccinated, the sooner we can see friends and family in person, get back to the activities we’ve been missing, and end the pandemic for good.

Get the latest updates on the COVID-19 vaccine
Our goal is to vaccinate as many people who choose to get vaccinated, as quickly and equitably as possible. 

This article reflects the most current information available at the time of publishing. 

1“Pfizer-BioNTech COVID-19 Vaccine Frequently Asked Questions,” Food and Drug Administration, FDA.gov, accessed March 4, 2021. 
2“Moderna COVID-19 Vaccine Frequently Asked Questions,” Food and Drug Administration, FDA.gov, accessed March 4, 2021. 
3“Janssen COVID-19 Vaccine Frequently Asked Questions,” Food and Drug Administration, FDA.gov, accessed March 4, 2021. 
4“Vaccine Effectiveness: How Well Do the Flu Vaccines Work?” Centers for Disease Control and Prevention, CDC.gov, accessed March 4, 2021. 
5“Estimated Influenza Illnesses, Medical Visits, and Hospitalizations Averted by Vaccination in the United States — 2019–2020 Influenza Season,” Centers for Disease Control and Prevention, CDC.gov, accessed March 4, 2021.
6Kaiser Permanente does not endorse the medication mentioned. Any trade names listed are for easy identification only.
7“What to Do if You Have an Allergic Reaction After Getting a COVID-19 Vaccine,” Centers for Disease Control and Prevention, CDC.gov, March 4, 2021.