The differences among COVID-19 vaccines

There are two types of COVID-19 vaccines: mRNA and viral vector vaccines. All of them have gone through rigorous standards for safety and effectiveness as other vaccines. When it comes to mRNA vaccines, it is a new type. But researchers have been studying and working with mRNA for decades.

What is mRNA?

mRNA stands for messenger ribonucleic acid (mRNA) molecule that provides cells with instructions for making proteins. The human body produces mRNA naturally and requires it in order to make vital proteins. mRNA vaccines use programmed and synthesized mRNA that teaches the body’s immune cells to create antibodies that can fight the COVID-19 virus. The Pfizer-BioNTech and the Moderna COVID-19 vaccines use mRNA.

Viral vector vaccines use harmless/weakened viruses to make specific SARS-CoV-2 (COVID-19) protein and teach the body to make a protein that will trigger an immune response when the COVID-19 virus enters your body. Most vaccines work this way. The Johnson & Johnson and the AstraZeneca-Oxford COVID-19 vaccines are vector vaccines.

Unlike vector vaccines, mRNA vaccines use the mRNA molecule instead of an actual bacteria or virus. The mRNA contained in the COVID-19 vaccine provides the body with information from the COVID-19 virus, thus allowing the body to make the SARS-CoV-2 spike protein. These proteins will then trigger the immune response, preparing the body to fight off the virus if it is affected by an actual infection.

Both COVID-19 mRNA and viral vector vaccines are held to the same high standards for safety, effectiveness and quality.

Since mRNA vaccines are a new type, people usually have lots of questions about them, unfortunately there are also myths and misinformation. Let’s discuss the most frequently asked questions and address most common myths.

Are the mRNA vaccines more efficacious than the viral vector vaccines?

All COVID-19 vaccines approved by the WHO are safe and effective. None of the COVID-19 vaccines has been directly compared in the same population and so the vaccine efficacy for the mRNA vaccines and viral vector vaccines cannot be directly compared with each other. However, mRNA vaccines have shown a high level of efficacy across all populations - The Pfizer BioNTech vaccine against COVID-19 has an efficacy of 95% while the Moderna vaccine has shown to have an efficacy of approximately 94.1%.

Can mRNA vaccines infect a person with the COVID-19 virus?

No. mRNA vaccines do not actually contain the virus that causes COVID-19 and so they cannot infect a person with the COVID-19 virus. After vaccination, it is not uncommon to experience body aches or low-grade fever. These are the signs that the body is launching a protective immune response and the vaccine is doing its job. The vast majority of COVID-19 vaccine recipients said that the side effects went away in a day or two.

Do mRNA vaccines change DNA?

No. There is a crucial difference between mRNA and DNA. Our genetic code, DNA, is large and double-stranded while the mRNA is single-stranded and programmed to deliver instructions to parts of the cell. DNA resides in the protected centre of the cell, the nucleus. The mRNA from the vaccine does not enter the nucleus and never interacts with the genetic material, DNA. There is absolutely no way that the mRNA vaccine changes DNA. The mRNA vaccine technology has been studied for decades, including in the context of vaccines against the Zika virus, rabies and influenza.

The COVID-19 vaccines made with messenger RNA or mRNA do not interact with the DNA at all. When the mRNA vaccine is introduced into the body, it engages with the cells to produce proteins. It does not enter the nucleus – the control centre of a cell – which houses the genetic material, DNA. Once the immune cells have used the instructions, they break down mRNA and it exits the body in a few weeks.

The Pfizer-BioNTech and Moderna COVID-19 vaccines use messenger RNA (mRNA) to prompt the body to make an immune response against COVID-19. mRNA vaccines do not alter DNA. The evidence says that mRNA vaccines are safe and effective and is approved by the WHO.

Are there any contraindications to mRNA vaccines?

Although rare, it has been reported that a few people experienced anaphylaxis (allergic reaction) after getting mRNA vaccines. If the allergic reaction occurs after the first dose of the mRNA vaccine, a second dose of the vaccine should not be administered. In this case, you can discuss with your doctor which vaccine would be suitable for the second dose to complete the vaccine series. A history of anaphylaxis to any component of the vaccine is a contraindication to vaccination.

Who can take mRNA vaccines?

The vaccine has been found to be safe and effective across all populations, including people at increased risk of severe diseases such as hypertension, diabetes, asthma, pulmonary, liver or kidney disease as well as chronic infections that are stable and controlled. Vaccine effectiveness is expected to be similar in pregnant and lactating women as in other adults. mRNA vaccines are administered for adolescents from 12-18 years of age.

However, there have been very rare reports of myocarditis (inflammation of heart muscle) following vaccination with the mRNA vaccines. It occurred more often among young males, aged between 12 and 29 and typically within a few days after a second dose. The condition is usually mild to moderate and most patients who received proper medical care and treatment and were quickly recovered. Studies are in progress to assess any further risks.

What are the recommended dosages of mrNA COVID-19 vaccines?

It is worth noting, that all the vaccines will significantly decrease your risks of severe illness or death. It will give you peace of mind as it will protect you and your loved ones. Stay healthy!

This article is made possible by the generous support of the American people through the United States Agency for International Development (USAID). The contents are the responsibility of authors and do not necessarily reflect the views of USAID or the United States Government