Important update: Healthcare facilities
CDC has updated select ways to operate healthcare systems effectively in response to COVID-19 vaccination. Learn more
To maximize protection from the Delta variant and prevent possibly spreading it to others, get vaccinated as soon as you can and wear a mask indoors in public if you are in an area of substantial or high transmission.
UPDATE
Given new evidence on the B.1.617.2 (Delta) variant, CDC has updated the guidance for fully vaccinated people. CDC recommends universal indoor masking for all teachers, staff, students, and visitors to K-12 schools, regardless of vaccination status. Children should return to full-time in-person learning in the fall with layered prevention strategies in place.
UPDATE
The White House announced that vaccines will be required for international travelers coming into the United States, with an effective date of November 8, 2021. For purposes of entry into the United States, vaccines accepted will include FDA approved or authorized and WHO Emergency Use Listing vaccines. More information is available here.
UPDATE
Travel requirements to enter the United States are changing, starting November 8, 2021. More information is available here.

Understanding Viral Vector COVID-19 Vaccines

Understanding Viral Vector COVID-19 Vaccines

What You Need to Know

  • Viral vector vaccines use a modified version of a virus that is different from the virus being targeted to deliver important instructions to our cells. The modified version of the virus is called a vector virus.
  • Like all vaccines, viral vector vaccines benefit people who get vaccinated by giving them protection against diseases like COVID-19 without them having to risk the serious consequences of getting sick.
  • Learn more about getting your vaccine.

The Johnson & Johnson Janssen vaccine, a viral vector vaccine, is among the COVID-19 vaccines authorized for emergency use in the United States.

How Viral Vector Vaccines Work

COVID-19 vaccines

COVID-19 vaccines

COVID-19 viral vector vaccines use a modified version of a different virus (a vector virus) to deliver important instructions to our cells.

  1. First, COVID-19 viral vector vaccines are given in the upper arm muscle. The COVID-19 vector virus is not the virus that causes COVID-19, but a different, harmless virus. It enters the muscle cells and uses the cells’ machinery to produce a harmless piece of what is called a spike protein. The spike protein is found on the surface of the virus that causes COVID-19.
  2. Next, the cells display the spike protein on their surface, and our immune system recognizes that the protein doesn’t belong there. This triggers our immune system to produce antibodies and activate other immune cells to fight off what it thinks is an infection. This response is what your body might do if you got sick with COVID-19.
  3. At the end of the process, our bodies have learned how to protect us against future infection with the virus that causes COVID-19. The benefit is that we get this protection from a vaccine, without ever having to risk the serious consequences of getting sick with COVID-19. Any temporary discomfort experienced after getting the vaccine is a natural part of the process and an indication that the vaccine is working.

Facts About COVID-19 Viral Vector Vaccines

COVID-19 viral vector vaccines cannot give someone the virus that causes COVID-19 or other viruses.

  • COVID-19 viral vectors cannot cause infection with COVID-19 or with the virus used as the vaccine vector.

 They do not affect or interact with our DNA in any way.

  • The genetic material delivered by the viral vector does not integrate into a person’s DNA.

The spike protein doesn’t last long in the body.

  • Scientists estimate that the spike protein, like other proteins our bodies create, may stay in the body up to a few weeks.

Viral Vector Vaccines Are Being Rigorously Studied for Safety

Viral vector vaccines are safe and effective.

Viral vector vaccines for COVID-19 are being held to the same rigorous safety and effectiveness standardsexternal icon as all other types of vaccines in the United States. The only COVID-19 vaccines the U.S. Food and Drug Administration (FDA) will make available for use in the United States (by approval or emergency use authorization) are those that meet these standards.

While COVID-19 vaccines were developed rapidly, all steps have been taken to ensure their safety and effectiveness.

How Viral Vector Vaccines Have Been Used During Recent Disease Outbreaks

Scientists began creating viral vectors in the 1970s. Besides being used in vaccines, viral vectors have also been studied for gene therapy, to treat cancer, and for molecular biology research. For decades, hundreds of scientific studies of viral vector vaccines have been done and published around the world. Some vaccines recently used for Ebola outbreaks have used viral vector technology, and a number of studies have focused on viral vector vaccines against other infectious diseases such as Zika, flu, and HIV.

Learn more about getting your vaccine.