Here's How Long The Pfizer And Moderna Vaccines Could Last

Many parts of the world are now past their initial vaccine rush. But as vaccines move on to other countries and communities, those who already received their jab are starting to wonder just how long their protection will last. The vaccines most people are familiar with are those we receive in childhood. They are either a one-time inoculation or require the occasional booster years down the road.

The COVID-19 vaccine is a different sort of protection, however. Rather than introducing a virus to our system as a means of teaching our bodies how to fight a disease, mRNA vaccines introduce a piece of the virus' protein, which teaches our cells to make the same protein (via the CDC). Once our body makes a copy of that protein, our immune system recognizes that it isn't natural to our bodies and kills it, thereby learning how to fight off the virus the original protein piece belonged to.

MRNA vaccines do all of this without entering the nuclei of our cells, which means it doesn't interact with our DNA at all. Rather it acts as a set of instructions to the surface of the cell, which are then destroyed shortly after. With COVID-19, that piece of protein is one of the external protrusions on the virus known as spike proteins, according to the BBC. Understanding the vaccine's process, however, doesn't necessarily mean we know how long our bodies retain those instructions.

The short answer is that nobody knows for sure how long the vaccine's protection lasts. As Dr. Jaimie Meyer, M.D., M.S., explained to Yale Medicine, "We can only say that a vaccine is protective as long as we are measuring it."

Dr. Meyer is an infectious disease specialist with Yale. She and other researchers have been monitoring the longevity of the COVID-19 vaccines by tracking the level of protection in people who signed up for the vaccines' early clinical trials. These clinical trials were shorter than normal because the need for vaccines was so dire. They have been going on long enough, however, for both Pfizer and Moderna to issue short term estimates on the lifespan of their vaccines.

A study in the New England Journal of Medicine reports that Moderna lasts at least six months, a lifespan matched by Pfizer's vaccine, according to the AARP. These time frames will be updated as the clinical trials continue and researchers can pinpoint when the vaccines' protection begins to decline. For now, however, vaccinated people can follow the CDC's current post-vaccination guidelines to make full use of the protection offered by their vaccine.