
COVID-19 Vaccine FAQs

What ages has the COVID-19 vaccine been approved for?
Pfizer and Moderna’s vaccine has been authorized for ages 6 months and up.
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How do Pfizer’s and Moderna’s COVID-19 vaccines work?
Both Pfizer and Moderna’s vaccines are made using the same technology: They inject a genetic molecule called mRNA, which causes a person’s cells to create a viral protein (called a “spike”) that triggers the desired immune response. There is no live virus involved – the mRNA molecule is simply a messenger that tells the body how to create an immune response, then it’s quickly broken down by the body and disappears.
How many doses does the COVID-19 vaccine take to be effective?
Nearly all COVID-19 vaccines being studied in the United States, including the approved vaccines by Pfizer and Moderna, require two shots: an initial dose followed a booster 3 weeks later for Pfizer and 4 weeks later for Moderna. While you do gain some immunity from COVID-19 with the first dose, it’s very important – for your own sake, and your community’s sake – to get both doses.
A few weeks after the second dose, you are protected from COVID-19 at a success rate of about 95% or 94% (Pfizer or Moderna, respectively). It’s worth noting that no vaccine is 100% effective, and this is among the highest efficacy seen with vaccines.
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Are Pfizer’s and Moderna’s COVID-19 vaccines safe?
COVID-19 vaccines are safe and effective. COVID-19 vaccines were evaluated in tens of thousands of participants in clinical trials. The vaccines met the Food and Drug Administration’s (FDA’s) rigorous scientific standards for safety, effectiveness, and manufacturing quality needed to support emergency use authorization (EUA). Click here for more information.
Are there any side effects of the COVID-19 vaccine?
Some people have mild side effects like soreness in their arm, chills, low grade fever, fatigue or headache for about 24 hours. These side effects are a normal part of the body’s immune system response, and commonly occur with many vaccines, including the flu shot.
Any effects of COVID vaccine on pregnancy, the developing fetus and while breastfeeding?
Evidence continues to build showing that COVID-19 vaccination during pregnancy is safe and effective. Click here for more information.
Will the COVID-19 vaccine wear off every year, like the flu shot?
Great question. This information is not yet available — so stay tuned.
Would you still recommend continuing full precautions after vaccination?
We will need to continue to practice physical distancing and mask wearing while indoors or in certain crowded outdoor settings. As more people are vaccinated increasing immunity, original guidelines will allow for some relaxation.
I saw on the news that a COVID-19 mutation was identified in the UK. Will the current COVID-19 vaccine still be effective?
All coronaviruses, including COVID-19, will tend to mutate and evolve over time. This just means that the genetic blueprint, or genome, of the virus is changing. The UK mutation appears to be associated with how contagious the virus is, but not with any part of the virus that affects how the vaccine works.
In other words, the current COVID-19 vaccine should still be effective against the mutated virus.
Modified from Connecticut Children’s Hospital