How Would a COVID-19 Vaccine Work?

By Sara Bondell - November 20, 2020

While COVID-19 cases continue to rise across the U.S., two major pharmaceutical companies announced that they have created vaccines that are highly effective at preventing the virus.

Pfizer and Moderna both say their vaccines are 95% effective at preventing COVID-19.

Vaccination is the process in which antigens are artificially introduced into the body to stimulate the immune system to develop antibodies, which protect you from infections. Most vaccines, like the flu shot, use a weakened or inactive form of the virus that does not cause the disease.

However, the Pfizer and Moderna vaccines use a messenger RNA, or mRNA, a relatively new technology in vaccine development. Instead of using the virus, RNA vaccines use pieces of genetic material to coax the body into developing defenses against future infection.

How Do RNA Vaccines Work?
DNA contains the genetic information of each living organism. It is made of four building blocks whose sequences instruct the body to create proteins. That process requires RNA, which acts as a messenger that carries the genetic information.

In an RNA-based vaccine, the RNA containing the genetic information to produce an antigen is introduced. This provides the body with the instructions to produce the antigen itself. The genetic information can be injected under the skin, into a vein or into lymph nodes and enter the body’s cells. Those cells will then use the RNA sequence of the antigen to synthesize the protein. From here, the body reacts like it would to a classical vaccine, triggering the activation of the immune system against the virus.

RNA vaccines are also being used in clinical trials for cancer. Researchers hope by taking advantage of the flexibility of RNA vaccine production, they can produce a vaccine with different antigens that can better target cancer cells, slow tumor progression and initiate an immune response in patients.

“The cancer community is very excited to see the robust efficacy data of these two mRNA-based vaccines as this vaccine technology holds tremendous promise as a novel, low cost method to treat pre-cancer and cancer in the future,” said Dr. Anna Giuliano, founding director of the Center for Immunization and Infection Research in Cancer at Moffitt Cancer Center.

portrait of blockquote author

"The cancer community is very excited to see the robust efficacy data of these two mRNA-based vaccines as this vaccine technology holds tremendous promise as a novel, low cost method to treat pre-cancer and cancer in the future."

- Dr. Anna Giuliano, Founding Director, Center for Immunization and Infection Research in Cancer

How Are RNA Vaccines Made?
RNA vaccines can be produced quicker and cheaper than traditional vaccines, making them a good option during a pandemic. They provide more flexibility to prevent or treat viruses that are rapidly evolving compared to a traditional vaccine.

While RNA vaccines can elicit an immune response, they are very fragile and can lose their efficacy when exposed to high temperatures. Moderna’s vaccine must be stored at minus 4 degrees Fahrenheit — equal to most home or medical freezer temperatures — and once thawed, it can be kept in a normal refrigerator for a month. Pfizer’s vaccine must be kept in a specialized ultra-cold freezer at minus 94 degrees Fahrenheit. Once taken out, it can be kept in a typical refrigerator for only five days.

What’s Next?
Both Pfizer and Moderna are gathering the required two months of safety data to gauge whether the vaccine has any negative side effects. They will then submit their findings to the U.S. Food and Drug Administration for emergency use authorization, a special provision allowing for the use of a product during a public health crisis before formal approval. This could happen before the end of the year, but the FDA has stressed it will authorize the use of a COVID-19 vaccine only if it is proved to be safe and effective.

After FDA approval, the Centers for Disease Control and Prevention will assess the vaccine and make a final ruling about whether to distribute it.

Contact the Author

Sara Bondell Medical Science Writer More Articles

Subscribe

Most Popular