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Understanding Vaccine Development
The steps behind the COVID-19 vaccine
BY KAREN A. JAMROG / ILLUSTRATION BY GLORIA DILLANIN
The pandemic upended many aspects of daily life, including where we spend our time. Especially with telecommute arrangements likely to remain more common than they were prior to COVID, our home environments matter more than ever. And, while we like to think of home as a safe haven, mold, carbon monoxide, pesticides, insects, secondhand smoke and other factors can endanger health. Here we highlight a handful of common home hazards and offer tips to keep you and your family safe.
It should help to know that, before a vaccine can be approved for use, it must undergo rigorous studies and testing that are designed to demonstrate safety and effectiveness.
Typically, vaccine development starts in a lab, where scientists research and test their ideas. If a concept proves promising, they eventually move forward with tests in animals to further investigate the safety and effectiveness of their potential vaccine, says Michael J. Gilbert, M.D., M.H.C.D.S., vice president of Medical Affairs and chief medical officer at Catholic Medical Center. Assuming animal tests go well, following a green light from the FDA, clinical trials in humans begin.
Clinical trials consist of three or four phases. Phase one is small, with 20 to 100 healthy volunteers who receive the shot. “The first is the small study, a very intensive study that’s really to look at safety and entails a lot of consideration of potentially unexpected reactions,” says Peter F. Wright, M.D., an infectious disease physician at Dartmouth-Hitchcock Medical Center and professor of pediatrics at Dartmouth’s Geisel School of Medicine. Researchers keep close tabs on the volunteers after vaccination, “and if everything was progressing well, they would then open the study to a larger group of people,” Wright says.
Subsequent phases of the clinical trials involve larger numbers of volunteers and include people who have underlying health conditions. By phase three, the vaccine under study is given to thousands of volunteers. Testing typically includes comparison with a control group, when some of the volunteers receive the vaccine, but others do not. Throughout each phase, researchers continue to gather data on the safety and effectiveness of the vaccine.
A fourth phase occurs post-licensure or post-approval for emergency use and is an ongoing effort to study long-term risks and benefits of the vaccine, as well as occurrences, Wright says, such as the blood clots that have occurred in roughly one in a million people who have received the Johnson & Johnson COVID-19 vaccine. “You never can do a clinical trial before licensure that enables you to detect that kind of extraordinarily rare event,” he notes.
Vaccines work by priming the immune system, Gilbert says. Some vaccines, such as the flu shot and the Johnson & Johnson
COVID-19 vaccine, contain a weakened, inactive or partial version of a virus or bacteria, which causes the immune system to react without causing the illness that the vaccine protects against. This controlled approach helps the immune system recognize and learn how to fight the bacteria or virus so that “the next time the virus or the bacteria enters our body,” Gilbert says, “we’re able to mount that immune response much more quickly and effectively so that we can kill off the invader before it causes significant damage.”
The Pfizer and Moderna COVID-19 vaccines use messenger RNA (mRNA) technology to achieve the same end result. The mRNA in the Pfizer and Moderna COVID-19 vaccines prompts the body to create a spike protein similar to what’s on the surface of the novel coronavirus, which the immune system then responds to. “The next time we are exposed to something with the spike protein,” Gilbert says, the immune system will quickly come to our defense. Although the Pfizer and Moderna COVID-19 vaccines are the first mRNA vaccines to be approved, scientists have studied and worked with mRNA for decades.
Sometimes booster shots are necessary to reprime the immune system or to address virus mutations that occur. At the time of this writing, it’s not known whether COVID-19 booster shots will be necessary, but Gilbert points out that boosters are very common in the vaccine world. “There are a significant number of vaccines that require a booster over the course of someone’s lifetime,” he says.
While being vaccinated might not always be something we look forward to, vaccinations can be lifesaving. And we can rest assured that to receive FDA approval, all vaccines must go through the extensive testing steps. The COVID-19 vaccines are no exception, despite the speed with which they were developed due to the pandemic. “None of those [testing] processes,” Gilbert says, “were shortcut or circumvented.” NH
Don’t throw out those masks just yet
Many people wonder why pandemic precautions such as mask-wearing in certain situations remain necessary following vaccination. There are multiple reasons, including the fact that it is not entirely known how long immunity lasts after vaccination, or how effective the vaccines are against new COVID-19 variants.
Also, at the time of this writing, experts aren’t sure about whether vaccinated people can spread the virus. “We really don’t know that [the COVID-19 vaccines] are entirely protecting against infection as opposed to protecting against illness,” says Peter F. Wright, M.D., an infectious disease physician at Dartmouth-Hitchcock Medical Center and professor of pediatrics at Dartmouth’s Geisel School of Medicine.
Scientists will continue to gather data to answer questions that surround COVID-19. But for now, at least, even vaccinated individuals should remain cautious to help protect themselves as well as others.
For more information, see the FDA’s “Vaccine Development – 101”: fda.gov/vaccines-blood-biologics/development-approval-process-cber/vaccine-development-101.
