Dr. Peter Gulick filled out a V-safe questionnaire on his smartphone after his first COVID-19 vaccine and each subsequent booster shot.
He indicated which side effects, if any, he experienced, and if he needed any medical attention in the days after the jab. It was more follow up than the typical flu shot or any other vaccine he could recall.
That level of surveillance, repeated for millions of people worldwide, has only strengthened his confidence in the safety of the vaccines developed more than four years ago to combat the virus that causes the disease -- SARS-CoV-2. Five years ago, on March 11, 2020, the World Health Organization declared COVID-19 a global pandemic.
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"Vaccines aren't perfect," said Gulick, a professor of medicine in the Department of Internal Medicine at Michigan State University. "There are side effects, but with the COVID vaccine, there haven't been any red flags."
The COVID pandemic created an environment for increased vaccine hesitance as Pfizer/BioNTech and Moderna developed new vaccine technology at record pace, and public health measures reached a new level of politicization.
Since the first COVID-19 vaccines were approved by regulators in 2020, more than 13.6 billion doses have been administered throughout the world, according to the World Health Organization.
By May 2023, the organization and the U.S. declared COVID-19 no longer constituted a public health emergency. About 82% of Americans had gotten at least one dose of vaccine, accounting for more than 984 million doses collectively. In Michigan alone, there have been more than 20.3 million doses administered to more than 6.36 million residents.
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COVID-19 vaccines "underwent the most intensive safety analysis in U.S. history," according to the Centers for Disease Control and Prevention. More than 10 million people participated in V-safe vaccine safety monitoring, completing more than 150 million surveys about their post-vaccine experience.
"With all these years of constant surveillance and follow up, if there was a real problem or something causing some real horrible symptoms, we would have seen it by now," said Gulick, who has been involved with infectious disease care and vaccinations for 40 years.
The most common side effects include injection side soreness, fatigue, headache, muscle and joint pain, chills, fever, and nausea, lasting one to four days.
Adverse events like inflammation of the heart, known as myocarditis or pericarditis, have been associated with mRNA vaccines, though incidences are rare and don't rise to the level of outweighing benefits of the shot.
Regarding the rare adverse event, Gulick noted it's no more common than a standard vaccine. In most cases, it's a reduced risk than COVID itself, which is also associated with an increased risk of myocarditis and organ damage.
In February, a research letter published by the American Medical Association indicated concerns regarding sudden cardiac arrest among athletes after the pandemic were overblown.
Researchers identified 387 events of sudden cardiac arrest from youth to professional athletics from 2017 to 2022, of which 203 occurred in the three years before COVID and 184 the three years after the start of the pandemic.
"Reports asserting otherwise were overestimating the cardiovascular risk of COVID-19 infection, vaccination, and myocarditis," wrote the authors. "Many athlete cases shown in social media video montages occurred before the pandemic yet claimed COVID-19 infection or vaccination raised the risk of (sudden cardiac arrest/death)."
On the other hand, the COVID vaccines have been associated with a reduced risk of a serious illness, post-COVID infection that can result in chronic conditions requiring comprehensive care and may cause disability, known as long COVID.
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"People can reduce their risk of developing long COVID if they've been vaccinated because it can reduce risk of getting sick in the first place, and reduce severity of illness," said Nancy Fleischer, a professor of epidemiology at the University of Michigan.
Michigan's confirmed COVID-19 death toll over five years is more than 39,760, according to state health records. There have been more than 7.1 million deaths worldwide, including 1.2 million Americans, according to the WHO.
Once vaccines were widely available, physicians began noting a shift in emergency rooms and on death records, with unvaccinated people more commonly experiencing worse outcomes with COVID-19.
The newness of mRNA vaccines was a common point of contention for people who declined to get the shot.
Developed by Pfizer/BioNTech and Moderna, the vaccines utilized a new technology using messenger RNA (mRNA). Molecules enter the cell and instruct it to provide a specific protein, triggering an immune response and preparing the body to fight off a future infection from a similar-looking protein.
However, more traditional COVID vaccines (vector viral) like the one developed by Johnson & Johnson and Oxford-AstraZeneca were associated with more statistically significant increases in rare adverse reactions, according to a multinational study published in April 2024, in the Journal "Vaccine."
Not only are mRNA vaccines not likely to go away any time soon, they're likely to be the future of vaccination.
Dr. Erica Michiels, medical director of the emergency department at Corewell's Helen DeVos Children's Hospital, said mRNA technology was crucial for getting a cost-effective vaccine against respiratory syncytial virus (RSV) approved last spring.
"I firmly believe COVID got us an RSV vaccination and it's far more effective than we've had available to us previously," Michiels said. "We have high hopes the RSV vaccine can start changing the landscape of what infant bronchiolitis looks like."
And while the current public health risk for the avian flu remains low, according to the CDC, Dr. Gulick said he'd expect an mRNA vaccine be developed if the H5N1 virus were to mutate and begin spreading from human to human.
"They're trying to develop a vaccine just in case, to be prepared," he said. "That mRNA technology is going to continue on; it's not going to go away."