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

How effective are the COVID-19 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, clinical trials for the Pfizer/BioNTech and Moderna mRNA vaccines and the protein-based Novavax vaccine found each reduced the risk of getting sick by more than 90%.
Subsequent studies have demonstrated that the vaccines are effective under real-world conditions. 

How were the COVID-19 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 against COVID-19?

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,

Could a COVID-19 vaccine become mandatory?

Some employers have required their employees to be vaccinated, or undergo regular testing, for COVID-19. The U.S. Equal Employment Opportunity Commission has said that employers aren’t prevented from having a mandatory vaccination policy for COVID-19 for employees who are physically in the workplace, as long as employers comply with federal laws stipulating that reasonable accommodations should be made for workers who cannot be immunized because of a disability or religious reason.
President Joe Biden also signed executive orders in September 2021 to require all federal workers and contractors who do business with the federal government to be vaccinated.

How much does a COVID-19 vaccine cost?

The COVID-19 vaccines are no longer provided by the federal government for free, but private insurance companies, Medicare and Medicaid, and some Centers for Disease Control and Prevention programs will cover them.
The CDC’s Bridge Access Program provides free vaccines to adults without health insurance and those whose insurance doesn’t pick up all of the cost, through local health centers, health care providers and certain retail pharmacies. The Vaccines for Children Program provides free vaccines for kids who are either Medicaid-eligible,

How can I report a potential vaccine safety issue?

The Centers for Disease Control and Prevention and the Food and Drug Administration have multiple surveillance systems for ensuring vaccine safety. If a health issue occurs after vaccination, people are encouraged to submit information to one of these systems, the Vaccine Adverse Event Reporting System. Experts do analysis and comb through the submissions to identify and follow-up on adverse reactions that might be due to vaccines.