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Vaccines: Myths, Facts, and Questions Answered


Many workers have expressed confusion about how the COVID-19 vaccine actually works. And rightly so–medical terms such as “shedding,” “mRNA,” and “spike proteins” have suddenly become parts of everyday language. We hope to clear up some of these terms in order to encourage more informed conversations and decisions and to shed a little light onto the controversy shrouding this vaccine.

What is mRNA? How does it work?

The most common COVID-19 vaccines used in the United States are mRNA vaccines. These are the vaccines that are used by Moderna and Pfizer. Messenger ribonucleic acid, or mRNA, is a type of RNA that shows our cells how to produce proteins. One way to think of mRNA is as a blueprint: a set of instructions for the construction of a protein. This metaphor is ideal, since it shows that mRNA is in no way involved in the protein’s construction: our cells do that work on their own! mRNA was discovered in the 1960s. Research about its practical application began in the 1970s. The first mRNA vaccines were developed for influenza: they were tested on mice in the 1990s. In 2013, the first mRNA vaccine was tested on humans. It was used for rabies and was considered a success. mRNA vaccines do not contain any live virus, nor do they change one’s DNA. mRNA material never enters the nucleus of our cells, which is where our DNA is stored. It never interacts with our DNA at all. It gives our cells the knowledge to produce a piece of spike protein. Your cell will produce this spike protein (which is harmless on its own), and your immune cells will recognize it as foreign. They develop an immune response that later functions to prevent the COVID-19 disease. Like any protein our body creates, the spike protein is metabolized in a matter of weeks.

Questions about the COVID-19 Vaccine:

How was the COVID-19 vaccine developed so quickly?

The robust history of the medical applications of mRNA has set a solid foundation for current and future research. We had a lot of information about mRNA and its success in vaccine trials before its implementation in the COVID-19 vaccine. The COVID-19 mRNA vaccines went through all required phases of clinical trials. all phases of clinical trials were thorough and completed before the COVID mRNA vaccine was made available to the public. No corners were cut in the process of developing the vaccine. One of the reasons it was available so quickly was because manufacturing of the vaccine occurred at the same time as licensure. After a vaccine is proven to be safe, it must be licensed by the FDA for its use in the USA. Vaccine manufacturers produced vials of the COVID-19 vaccine while it was getting its licensure, knowing that the vaccine was safe and would be approved. This step ensured that the vaccine would be available as soon as it received its final approval.

Can any COVID-19 vaccines “shed”?

“Vaccine shedding” (viral shedding resulting from vaccination) is when viral components of a vaccine are released outside of the body. This can only occur when a live, weakened strain of a virus is used in a vaccine. No COVID-19 vaccine authorized for use in the US is capable of viral shedding, since no COVID-19 vaccine contains a living strain of the virus. Shedding cannot occur in mRNA vaccines.

Does the COVID-19 vaccine affect fertility?

There is no evidence that the COVID-19 vaccine has an impact on an individual’s fertility, lactation, or pregnancy. In fact, it is recommended that pregnant individuals receive the COVID-19 vaccine as pregnancy can weaken one’s immune system.

How long does protection from the COVID-19 vaccine last?

COVID-19 vaccines are extremely effective at preventing severe disease and death. Less than 8% of hospitalizations and deaths occur in vaccinated people. The vast majority of deaths and instances of severe disease occur in the unvaccinated. It’s not yet known how long protection provided from the COVID-19 vaccine may last. With different variants, vaccines, and timelines, it’s difficult to study. Here’s what we do know: Across the board, there is a clear trend of vaccines losing efficacy over time. This is why it’s important to get a booster. Regardless, all vaccines have been shown to be more than 50% effective at preventing the virus after 8 months. Broadly speaking, It seems that protection provided by the vaccine lasts around 6-9 months. It varies based on many factors: exposure and community spread, individual immune responses, type of vaccine, and more. Moderna and Pfizer vaccines seem to hold up the best Johnson and Johnson seems to fade most quickly. Though vaccine protection does wane, vaccinated people are far less likely to experience severe disease and death if they do contract COVID-19.

We hope this provides you with some information and talking points about the COVID-19 vaccine!

Family medicine doctor Roberta Wedl, M.D. was consulted and contributed to the content of this article.