Are certain vaccines more effective than others?

To measure how well a vaccine works in a clinical trial, the Food and Drug Administration (FDA) first looks at the number of people who fell ill with the disease. Then the agency compares whether they received the vaccine or the placebo (a harmless, inactive substance that looks identical to the vaccine being tested). If a greater share of those who are sick received the placebo instead of the vaccine, then the vaccine has met an acceptable efficacy standard.

Learn more about this process here.

Covid-19 vaccines currently authorized in the United States demonstrated extremely high efficacy in clinical trials. The Pfizer and Moderna vaccines had efficacy rates of 95 percent and 94.1 percent, respectively. Therefore, either the Pfizer or Moderna vaccine will provide similar protection against infection from COVID-19. People should accept the first vaccine that becomes available to them in their area.

Related Questions
Where should I go for trusted and up-to-date information on Covid-19 vaccines?
The Centers for Disease Control and Prevention (CDC) has great information on the Covid-19 vaccines, including a FAQ page. Another CDC resource will direct you to state Department of Health websites. Those sites will help you determine when you can get the vaccine in your area. This website (covidvaccinefacts.org) will also be continually updated to provide trusted information on all Covid-19-related matters, including vaccines. You can find an interactive state map with links to state…
I'm young and healthy. Should I get vaccinated?
While not considered to be at high risk for severe complications from Covid-19, serious cases do occur among younger, healthier people. The Centers for Disease Control and Prevention (CDC) also warns of the potential long-term health effects of Covid-19 infection, even for those who experienced mild illness. In addition, young people can still be carriers of the virus and contribute to community spread without ever having symptoms. Therefore, you should still get vaccinated when one becomes…
Is a monoclonal antibody treatment the same as a vaccine? If not, what's the difference?
Monoclonal antibody treatments are not the same as vaccines. Monoclonal antibodies are medicines that directly deliver man-made antibodies against a virus to your body to help fight off infection. To treat Covid-19, the FDA has approved two monoclonal antibody treatments for emergency use -- bamlanivimab and the casirivimab and imdevimab antibody cocktail. These treatments are given to patients through an IV and attack the natural spike protein found on the surface of the Covid-19 virus. The…