How Do mRNA COVID-19 Vaccines Work?

Many types of vaccines have been developed for COVID-19. The common goal of all vaccines is to trigger an immune response that is specific to COVID-19 virus. Although all the COVID-19 vaccines aim to achieve protection from COVID-19, they use different ways to train our white blood cells. The COVID-19 virus has spikes of a protein structure called an S protein on the surface of the virus. These spike proteins help attach the virus to the cells and cause the disease. Our immune system recognizes this spike protein as foreign and produces long-lasting immune cells and antibodies (fighter cells) that stay in the blood and protect the person. If a vaccinated person is exposed to coronavirus time, their immune system will respond faster and more effectively to fight the virus. The vaccinated person gets protection against the disease without getting critically sick. Types of COVID-19 vaccines include

Messenger RNA (mRNA) vaccines: COVID-19 mRNA vaccines use a genetic code called RNA. After vaccination, the RNA instructs the white blood cells to produce harmless spike protein pieces. The body’s immune system recognizes the spike protein as foreign and begins building an immune response and making antibodies. Pfizer-BioNTech and Moderna COVID-19 vaccines are mRNA vaccines. mRNA vaccines are available as two-dose vaccines given 28 days apart.

Viral vector vaccines: In this type of vaccine, a genetic material from COVID-19 virus is inserted into another weakened live virus such as adenovirus. After vaccination, the weakened virus known as a viral vector enters our body cells. It delivers the imbibed genetic material from the COVID-19 virus that gives instructions to the cells to make harmless copies of the coronavirus spike protein. Once the cells display spike proteins on their surfaces, the immune system recognizes the protein as foreign and responds by creating antibodies and defensive white blood cells. Oxford-AstraZeneca, Sputnik V and Johnson & Johnson–Janssen COVID-19 vaccines are viral vector vaccines.

Protein subunit vaccines: Protein subunit vaccines use a noninfectious harmless protein component of coronavirus directly, usually the spike protein. This protein that is found on the surface of the virus is manufactured in a laboratory. When the vaccine enters the body, the immune cells recognize the spike protein as foreign and begin building T-lymphocytes and antibodies. The Novavax COVID-19 vaccine is a protein subunit vaccine.

Inactivated vaccines: Unlike other vaccines, inactivated vaccines contain the entire coronavirus that has been chemically modified to make it inactive. Usually, a chemical called beta-propiolactone is used to inactivate the virus in the vaccines. This type of vaccine does not produce long-lasting strong immune reaction as other vaccines. Hence, people may need booster shots. Adjuvants may be used in the inactivated COVID-19 vaccines to generate a stronger immune response. To provide immunity in the long run, booster shots may be necessary. Sinovac, Sinopharm and COVAXIN are inactivated vaccines.

COVID-19 vaccines are expected to provide some level of protection against new virus variants or mutation. The extent of protection in mutant strains needs further studies.

The efficacy for most COVID-19 vaccines is around 60-70 percent. mRNA vaccines are more efficacious and may provide more than 90 percent protection.

A person with an active COVID-19 must delay the vaccination by around six weeks. A person with `history of COVID-19 can take the vaccine provided the diagnosis was six weeks ago.

Doctors advise vaccination people to people with a previous infection. Antibodies from the infection persist for only three to five months. The vaccine-induced antibodies may last longer.