COVID-19 Vaccines 101: Viral Vectors, mRNA Technology, and Vaccine Development

Close-up of gloved hands injecting COVID-19 vaccine into patient's arm

While millions of people around the world have received the COVID-19 vaccination, vaccine misinformation still persists, fueling doubts and hesitancy among unvaccinated populations.

Compiled from interviews with experts in public health, healthcare analytics, virology, infectious diseases and more, the following are bite-sized informational videos reviewing the basics of mRNA and viral vector technology and the process of vaccine development.

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About mRNA COVID-19 vaccines

mRNA technology may be new to patients and clinicians, but researchers have been studying the technology for decades for prevention or treatment of a range of diseases, including influenza, Zika, and rabies.

While it is a genetic technology, mRNA does not enter the cell’s nucleus, nor does it alter DNA. When used in the COVID-19 vaccines, mRNA molecules send a message to the immune system to produce antibodies against the virus, but it does not contain the live virus.

About the viral vector COVID-19 vaccine

Like mRNA technology, viral vector vaccines have been studied for decades and have been used successfully in response to past Ebola outbreaks.

To stimulate an immune response, these vaccines use a modified vector, i.e. a different virus than the targeted pathogen, as a vehicle. Like a microscopic taxi, the vector-vehicle transports the genetic material needed by cells to recognize and attack the targeted pathogen.

The COVID-19 viral-vector vaccine approved for use in the U.S. uses a modified adenovirus as the vector. A gene unique to the COVID-19 virus is added to the vector to prompt production of the specific antibodies that target and destroy the virus.

The COVID-19 viral-vector vaccine does not contain the live SARS-CoV-2 virus and does not cause illness from either COVID-19 or the adenovirus vector. It also does not alter DNA.

About the COVID-19 vaccine development process

A good deal of vaccine hesitancy stems from the belief that the vaccine was rushed. Here are four things to know about the vaccine development process.

  1. It didn’t start from scratch. Coronaviruses have been studied for more than 50 years, and scientists built on that research to develop vaccines for other diseases like SARS, MERS, and now COVID-19.
  2. The world mobilized quickly. Thanks to scientific advancements and global cooperation, scientists pinpointed the virus’ genetic makeup within days of the first reported case of SARS-CoV-2.
  3. Funding was fast-tracked. In the U.S., Operation Warp Speed injected a flood of funds to accelerate the development and manufacture of COVID-19 vaccines.
  4. Approval relied on an independent review. The COVID-19 vaccine underwent the same scrutiny as any other vaccine, including:
    • Tightly controlled clinical trials
    • Thorough review by an autonomous panel of doctors and scientists

Like all vaccines, both viral vector and mRNA vaccines have been rigorously tested in large clinical trials and meticulously reviewed by a safety monitoring board.

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