How much protection does the first vaccine dose give?

Consider a recent study carried out by the Centers for Disease Control and Prevention (CDC) of the authorized vaccines. Pfizer-BioNTech and Moderna's vaccines were found to be 82 percent effective after one dose in preventing people from getting Covid-19 cases with symptoms.

The Pfizer-BioNTech Covid-19 vaccine demonstrated 52 percent efficacy in protecting against disease after the first dose, according to the clinical trial data. The Moderna vaccine demonstrated 80.2 percent efficacy after the first dose. To maximize the protection from these vaccines, it is important to get both doses.

 The Johnson & Johnson vaccine was 85 percent effective in preventing severe disease across all regions studied, and showed protection against COVID-19 related hospitalization and death, beginning 28 days after vaccination, according to existing data.

Learn more about vaccine efficacy here.

Read more about the clinical trials for the FDA-authorized Pfizer-BioNTech, Johnson & Johnson, and Moderna vaccines.  

What are the side effects of Covid-19 vaccines?
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Related Questions
Have vaccine side effects resulted in any deaths?
Reports of life-threatening reactions resulting from the side effects of Pfizer-BioNTech, Moderna, and Johnson & Johnson vaccines are extremely rare. Still, it's important to address any concerns people may have.
Can groups, businesses, or organizations require that I get vaccinated?
The right to require Covid-19 vaccination in places of business, entertainment, and education ultimately depends on state or local law. So be sure to check requirements specific to your area.
Are Covid-19 vaccines safe for children?
The FDA has authorized the use of Pfizer-BioNTech's vaccine for children 12 years and older. FDA’s authorization was based on data showing the vaccine is safe and effective in this age group. Pfizer-BioNTech's vaccine has been through extremely tough safety tests, which includes continuing scientific studies in children and teenagers.