How Potential COVID-19 Vaccines Are Developed and Tested Javascript must be enabled to use this site. Please enable Javascript in your browser and try again. × Search search POPULAR SEARCHES SUGGESTED LINKS Join AARP for just $9 per year when you sign up for a 5-year term. Get instant access to members-only products and hundreds of discounts, a free second membership, and a subscription to AARP the Magazine. Leaving AARP.org Website You are now leaving AARP.org and going to a website that is not operated by AARP. A different privacy policy and terms of service will apply.

Will a COVID-19 Vaccine Be Safe

If you re worried about a vaccine being rushed to market here s what experts say you should know about the risks

South Agency/Getty Images The novel coronavirus has spread across the nation at record speed, infecting millions of Americans and killing more than 150,000. Although attacks people of all ages, genders and ethnicities, older adults are particularly vulnerable — about 80 percent of COVID-related deaths occur among people over age 65, according to the Centers for Disease Control and Prevention (CDC). Almost two dozen vaccines are in various stages of testing around the world, with one, Moderna's mRNA-1273, already showing promising results. But most vaccines typically take anywhere from eight to 15 years to develop, test and produce. Up until now, the fastest was the mumps vaccine, which took four years. Here in the United States, the government vowed this spring to have a COVID-19 vaccine ready within 12 to 18 months and has created a project known as Operation Warp Speed, investing over $1 billion with the goal of providing enough vaccine for 300 million Americans by January. Get instant access to members-only products and hundreds of discounts, a free second membership, and a subscription to AARP the Magazine. But with that accelerated timeline come worries that any vaccine developed will not have had enough testing — especially safety testing — behind it. History shows it pays to be cautious. Case in point: the Cutter incident of 1955, when some batches of an approved polio vaccine turned out to contain insufficiently inactivated live virus. This led to more than 250 cases of polio, many of which resulted in paralysis. More recently, the RotaShield vaccine, the first rotavirus gastroenteritis vaccine, was recalled in 1999, about a year after U.S. Food and Drug Administration (FDA) approval, after it was linked to bowel obstruction in infants. The good news: Experts say you can feel very confident that any vaccine that makes it through FDA approval today is safe. “It is important to reassure older adults that we are not cutting corners at all,” says Mark Mulligan, M.D., director of the Division of Infectious Diseases and Immunology at the New York University Langone Health in New York City. “The speed comes from doing things in parallel that would normally done sequentially — for example, producing a vaccine at the same time as we're doing studies to make sure it's effective, safe and tolerated well." To understand the steps researchers are taking to streamline vaccine development, it's helpful to understand a little bit more about vaccines. These are designed to mimic the immune response you develop after you're exposed to an infection. “They prime your immune system to recognize a certain virus or bacteria and to produce antibodies against it, so that the next time it shows up, your body revs up with enough force to fight it,” says William Schaffner, M.D., professor of preventive medicine, Division of Infectious Diseases, at Vanderbilt University Medical Center in Nashville. This teaches the immune system to recognize the pathogen, enabling the body to clear the infection the next time it is exposed. AARP Membership — $12 for your first year when you sign up for Automatic Renewal Get instant access to members-only products and hundreds of discounts, a free second membership, and a subscription to AARP the Magazine. is already in place. “A lot of research went into creating vaccines for two other dangerous coronaviruses — the SARS coronavirus [in 2002] as well as the MERS coronavirus” in 2012, Schaffner says. As a result, many drug companies already have technology that they've been able to use. In the case of COVID-19, scientists have been able to identify the sequence for a key protein on its surface called a spike protein. Moderna's vaccine transports a genetically engineered version of this spike protein via RNA, for example, while other companies, like Johnson & Johnson and AstraZeneca, use a weakened version of the adenovirus (the virus that normally causes the common cold). Each of these two approaches would stimulate your immune system to fight the disease caused by the virus so that you develop immunity to that disease, without exposure to the disease itself, Mulligan says. The to outline what's expected for companies developing a potential COVID-19 vaccine, stating that it “will not cut corners.” This means that vaccine developers will be expected to undergo the rigorous clinical trial process all other vaccines have gone through, says vaccine expert Anna Durbin, M.D., professor of international health at the Johns Hopkins Bloomberg School of Public Health. Here's a look at what that entails. Entertainment $3 off popcorn and soft drink combos See more Entertainment offers >

Phase 1 Testing begins on a small group of young healthy people

Scientists test the vaccine in a small group of volunteers — usually 20 to 50 — to see if they develop an immune response. Subjects also are monitored for side effects. “These are done in young, healthy people who already have pretty robust immune systems, for safety reasons,” Durbin says.

Phase 2 The number of test subjects expands

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