Why is it important to get your second dose of the Pfizer or Moderna vaccine?

A year ago, it was hard to believe that multiple vaccines would be widely available. (Thank you, science!) The world is now much better equipped to manage the coronavirus—and the more vaccine series completed, the better off we will be as Arizona returns to normal.  

Two of the three vaccines available in Arizona—Pfizer and Moderna—are mRNA vaccines. They are both made with a type of vaccine technology that uses mRNA to tell the body how to make a protein from the coronavirus, which triggers an immune response. In clinical trials, the Pfizer vaccine was shown to be 95% effective against COVID-19, while Moderna's had an efficacy rate of 94.1%.

But reaching this high level of protection requires not just one—but two doses of these vaccines.

If you’re considering skipping the second shot because you think it’s unnecessary or inconvenient, please think again.

Here are five reasons why you need both doses of these COVID-19 vaccines:

1. The clinical trial results are based on two doses—not one. The efficacy rates are based on trial results that showed these vaccines are most effective after two doses spaced a few weeks apart. 

A study of more than 43,000 people found that one dose of the Pfizer coronavirus vaccine was only 52% effective after 21 days. Efficacy, however, jumped to 95% seven days after the second dose of the vaccine. 

2. That second dose is necessary to develop long-term protection. It's not unusual for vaccines to require two or even three doses to be most effective. The first dose of a vaccine primes the immune system, and the second dose triggers a more potent immune response. 

3. Vaccine side effects are normal—and temporary. Side effects can be temporarily uncomfortable, but they aren’t a reason to skip dose two. They’re not only normal but they are also a sign that the vaccine is working. Moreover, these side effects typically disappear within a few days.

4. Skipping a second dose can cause harm. If you skip your second shot of the Pfizer or Moderna vaccine, you may not be fully protected but feel that you are immune. If you let your guard down and take risks, it could not only put you at risk for infection but also fail to stop the spread of the coronavirus to others.

5. Getting just one shot could allow the virus to evolve into a new variant. Some scientists who study viruses speculate that if people skip the second shot of the two-dose coronavirus vaccines, the virus may continue to mutate. This could make existing vaccines less effective against the virus. 


Additional COVID-19 resources

For more information about COVID-19, vaccines, and how you can protect yourself and your family, visit azblue.com/coronavirus.

This content originally appeared on Sharecare.com, Don’t Skip Your Second COVID Shot - Sharecare.


Blue Cross, Blue Shield, and the Cross and Shield Symbols are registered service marks of the Blue Cross Blue Shield Association, an association of independent Blue Cross and Blue Shield Plans. This information is provided for educational purposes only. Individuals should always consult with their healthcare providers regarding medical care or treatment, as recommendations, services or resources are not a substitute for the advice or recommendation of an individual’s physician or healthcare provider. Services or treatment options may not be covered under an individual’s particular health plan. © 2021 Blue Cross Blue Shield of Arizona, Inc., an independent licensee of Blue Cross and Blue Shield Association.

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Last Updated: 06/04/2021