Traditional vaccines contain weak or inactive forms of viruses or bacteria. They stimulate your body's immune system to respond to the disease-causing substance, which protects you if you're exposed to it in the future. More recently, scientists have developed vaccines that instead use genetic material from viruses or bacteria, such as RNA or DNA, to help your body mount this defense.
mRNA (messenger RNA) vaccines are already in use against the virus that causes COVID-19. Scientists are now looking to use a DNA vaccine as another option to fight COVID-19 and other infectious diseases.
What Is a DNA Vaccine?
DNA (deoxyribonucleic acid) is genetic material found inside the cells of every living organism. You could think of it as an instruction booklet for how cells reproduce themselves in your body.
Since the 1990s, experts have been researching how they could use DNA to create vaccines. These are called DNA vaccines.
How Does the DNA Vaccine Work?
When you get a DNA vaccine, your cells translate the gene particle from the virus or bacteria into a protein that your body recognizes as a foreign element. Your immune system then creates antibodies that fight these particular proteins, stop them from attaching to your cells, and eventually destroy them. The vaccines teach your body to recognize these proteins to prevent future infections.
How Does a DNA Vaccine Differ From Traditional Vaccines?
Traditional vaccines are made using whole viruses or bacteria, or parts of them like proteins or sugars.
Both RNA and DNA vaccines instead use genetic material from the virus or bacteria. The material gives your body instructions to make specific foreign proteins. This teaches your body to recognize these proteins as a threat and fight them.
How Do DNA Vaccines Differ From mRNA Vaccines?
The two vaccines work in a similar way. But one sends instructions for making the protein as DNA, and the other sends them as messenger RNA.
Neither an mRNA or a DNA vaccine changes your existing genes in any way. And neither can infect you with a disease.
What Are the Advantages of DNA Vaccine?
DNA vaccines have several potential advantages over traditional and even mRNA vaccines:
They can be developed quickly. It’s easier to create large amounts of a gene than to make proteins or grow bacteria or viruses. Speed is essential when disease-causing viruses or bacteria are mutating and spreading quickly.
They're easy to transport and store. DNA is stable. It doesn’t need to be stored at low temperatures like the mRNA vaccines.
They're cheaper to make. It’s less expensive to make and purify large amounts of DNA from viruses or bacteria than to create traditional vaccines.
DNA Vaccine and COVID-19
In September 2021, India gave an emergency authorization to the world’s first DNA vaccine for human use. Called ZyCoV-D, the vaccine was developed by the Zydus Cadila pharmaceutical company. It was approved for emergency use in adults and in children 12 and older.
Unlike mRNA vaccines for COVID-19 like Pfizer-BioNtech or Moderna, which require two doses, ZyCoV-D DNA vaccines require three doses, given 28 days apart. Instead of a needle, it's given with a device that pushes a stream of vaccine into your skin. A study involving 28,000 volunteers found that the ZyCoV-D vaccine was 67% effective at preventing serious illness from COVID-19.
DNA Vaccines and Challenges
DNA vaccine technology is rapidly improving. Researchers are studying DNA vaccines to fight HIV and certain cancers. But as of September 2021, the FDA had approved the DNA vaccine only for use in certain animal diseases, such as West Nile Virus in horses and melanoma in dogs.
We need more research into the use of DNA vaccines against COVID-19 and other diseases caused by viruses or bacteria. Scientists still don't properly understand much of the immune response caused by DNA vaccines. And we have limited data on their safety, possible side effects, and effectiveness.