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A Project of The Annenberg Public Policy Center
SciCheck’s COVID-19/Vaccination Project

How do we know what ingredients are in a vaccine?

The full ingredient list for any authorized COVID-19 vaccine can be found on the Centers for Disease Control and Prevention website and in a variety of documents on the Food and Drug Administration’s website, including in a fact sheet for vaccine recipients that’s available in numerous languages. 
Both the Pfizer/BioNTech and Moderna vaccines contain messenger RNA, or mRNA;

How do we know vaccines are safe?

No vaccine or medical product is 100% safe, but the safety of vaccines is ensured via rigorous testing in clinical trials prior to authorization or approval, followed by continued safety monitoring once the vaccine is rolled out to the public to detect potential rare side effects. In addition, the Food and Drug Administration inspects vaccine production facilities and reviews manufacturing protocols to make sure vaccine doses are of high-quality and free of contaminants.

How safe are the vaccines?

More than half a billion doses of COVID-19 vaccines have now been administered in the U.S. and only a few, very rare, safety concerns have emerged. The vast majority of people experience only minor, temporary side effects such as pain at the injection site, fatigue, headache, or muscle pain — or no side effects at all. As the Centers for Disease Control and Prevention has said, these vaccines “have undergone and will continue to undergo the most intensive safety monitoring in U.S.

How effective are the vaccines?

All of the authorized and approved vaccines are effective at preventing severe COVID-19.
Against earlier forms of the coronavirus, the vaccines were highly effective at preventing symptomatic illness. For example, the Pfizer/BioNTech vaccine, which was the first COVID-19 vaccine to receive full approval from the Food and Drug Administration, showed a final efficacy of 91% against symptomatic illness in its phase 3 trial, meaning that under the conditions of the trial the vaccine reduced the risk of getting sick by 91%.

How were the vaccines tested?

The authorized or approved vaccines were initially tested in animals and early phase clinical trials, in which scientists evaluated different doses, checked for the expected immune responses and monitored for potential safety issues. To find out whether the shots prevent disease and are safe, the vaccines that passed the first set of tests were then evaluated in phase 3 trials.
The Moderna and Novavax phase 3 trials each included about 30,000 volunteers,

Pace of U.S. Vaccinations vs. the World

Pace of U.S. Vaccinations vs. the World

President Joe Biden boasts that the U.S. is on pace to be the first country in the world to vaccinate 100 million people. That’s true, but per capita the U.S. is not tops in the world in vaccinations.

A Guide to Johnson & Johnson’s COVID-19 Vaccine

A Guide to Johnson & Johnson’s COVID-19 Vaccine

The Johnson & Johnson vaccine is the third COVID-19 vaccine to be authorized by the Food and Drug Administration. Here, we give a rundown of basic facts about the vaccine and an overview of how it works.

No Evidence Vaccines Impact Fertility

No Evidence Vaccines Impact Fertility

Q: Do the COVID-19 vaccines cause infertility?
A: There’s no evidence that approved vaccines cause fertility loss. Although clinical trials did not study the issue, loss of fertility has not been reported among thousands of trial participants nor confirmed as an adverse event among millions who have been vaccinated. 

How long will a person be protected if vaccinated?

It’s not known exactly how long vaccination lasts, particularly against the omicron variant. But studies of previous variants have suggested that COVID-19 vaccination protects against infection or mild disease for several months, while protection against more serious illness is longer-lasting, on the order of six months or more.
A systematic review of studies conducted prior to omicron, for example, found that for the four main COVID-19 vaccines used worldwide,

How does community immunity apply to COVID-19?

Community immunity, often referred to as herd immunity, refers to a situation in which enough of a population is immune to an infectious disease, either through vaccination or prior infection, to largely stop transmission of the disease and indirectly protect those who aren’t immune. The more contagious the disease, the higher proportion of people need to have immunity to get community immunity.
This classical definition applies to diseases such as measles,