Understanding the Science Behind a COVID-19 Vaccine
Vaccines have proven, time and time again, to be safe and effective at preventing disease. But with a virus as new as coronavirus, how soon is too soon to get vaccinated?
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Vaccines: They’ve saved the world from smallpox (a disease that killed or grossly disfigured hundreds of millions of people over the past several centuries), eliminated the risk of American children becoming crippled from polio, and saved millions and millions of lives. Overwhelmingly, vaccines are safe and prevent the spread of deadly diseases.
But the novel and unknown create a sense of fear, and fear can be politically manipulated. Whether it’s a virus or a vaccine, how do we use facts and science to help us choose wisely in these unprecedented times?
In April, when the Department of Health and Human Services (HHS) announced Operation Warp Speed (OWS), a mission to deliver 300 million doses of a safe, effective vaccine for COVID-19 by January 2021, many Americans were elated, but the scientific community cringed. And they expressed a similar concern several days ago after The New York Times obtained documents from the Centers for Disease Control and Prevention (CDC) which instructed states to prepare to distribute a vaccine to high-risk groups as soon as late October or early November. It’s convenient timing for President Donald Trump, who has made the creation of a vaccine and subsequent end to the pandemic a key part of his re-election campaign.
“As soon as I heard the name Operation Warp Speed, I thought, ‘that’s not going to inspire a lot of confidence in this vaccine,’” says Sandra Kesh, M.D., deputy medical director and infectious disease specialist at Westmed Medical Group. “It usually takes years to really get a vaccine into production.”
Exactly how many years does it take? On average, it can take anywhere from four to 10 years for a vaccine to come to market, but some take even longer. There are two reasons for this: money and clinical trials. Typically, pharmaceutical companies will receive some public funding, but they must raise the majority of money needed to conduct clinical trials and produce a vaccine. So, they often turn to venture capitalists, and it can take years to prove that their vaccine is worthy of investment.
In the case of a COVID-19 vaccine, HHS has eliminated that hurdle, giving several companies millions or billions of dollars to run clinical trials and produce a vaccine, no strings attached. If their vaccine fails to meet the Food & Drug Administration’s (FDA) standards, they’re not required to refund the money.
In regards to clinical trials, there are three time-consuming factors: creating a potential vaccine, gathering enough volunteers, and proving safety/efficacy. It’s not easy to develop a vaccine, especially when you know so little about the virus. Why? To get a vaccine to work—meaning, protect a person from disease—the immune system needs to receive precisely the right amount and type of signals to produce the correct bodily response. Your body naturally produces two types of white blood cells designed to target germs: B cells (they make antibodies) and T cells (they kill the infected cells). When an unknown germ enters your body, it takes these cells several days to respond, but once they do, they store a memory of the germ so they can provide a more rapid response if it ever returns. Vaccines are designed to mirror this process by encouraging your cells to form these memories without the host (you) actually experiencing symptoms of the virus. But because scientists know so little about the coronavirus, they don’t know exactly what will trigger these white blood cells to attack and remember the next time.
“The vaccines we’re currently testing are so new that we don’t yet have a good idea of what’s going on,” says Greg Maguire, Ph.D., and CEO/CSO/Founder of BioRegenerative Sciences, Inc. “But, we’re learning a lot because the scientific world has jumped on this. It’s surprising how many people are working on this and how much good work we’ve already seen. But still, we’re only six months into this disease, so there’s just a whole lot we don’t know..”
After a vaccine is proven to work in a lab setting, the next step is to undergo three phases of testing and clinical trials, passing safety and efficacy requirements at each one before continuing on to the next. Then, a company can apply for FDA approval.
In Phase 1, which takes place in a controlled clinical setting over several months, approximately 20 to 100 healthy adults are given the vaccine to ascertain any serious side effects and if it might work. Phase 2 increases the amount of volunteers to several hundred or thousand, observing the immune response and identifying short-term side effects. In Phase 3, tens of thousands of volunteers of different populations with a variety of risk factors will receive the vaccine or a placebo and then continue to live their lives, preferably in situations where they’ll likely be exposed to the coronavirus. It’s this phase that will determine the final formulation and dosage, along with a real-life understanding of the vaccine’s safety and efficacy.
If you speak with scientists or medical health professionals, most will tell you that a COVID-19 vaccine will only be approved if it’s safe and effective. But politics has complicated public health this year in ways that have surprised the medical community, government officials, and the American public alike. Some say they’ll be first in line to receive the vaccine, while others will wait a bit longer – anywhere from six months to a year or so – to review the vaccine’s safety and efficacy in the general population. But all are confident that a vaccine is necessary in order to get this virus under control.
Luckily, the average person is able to review the same data as the experts by visiting the FDA’s or the National Library of Medicine’s websites. Understanding how they evaluate “safety and efficacy” can help you feel confident in receiving the new vaccine yourself.
First, let’s examine safety. In order to determine if a vaccine is safe, the experts interviewed for this story believe it needs to be tested on a large number of people, approximately 30,000 – 50,000. Of those tested, the rates of serious adverse reactions should be extremely low.
“Serious adverse reactions include anything related to your heart rhythm, blood clots, a change in your kidney or liver function, neurologic problems or other serious conditions,” says Darshana Shah, Ph.D., scientific affairs and business development manager at Avion Pharmaceuticals. “These are placed in two columns – one is due to the vaccine and the second is ‘other reasons.’ For example, if somebody has diabetes, they may react differently than a normal, healthy individual. Their results would be in the ‘other reasons’ column.”
According to Maguire, a vaccine is considered safe if less than one percent experience serious side effects. But if you have an underlying health condition, you need to review the “other reasons” section to determine if it’s safe for your specific diagnosis.
“Often, they try to stratify the volunteers who had problems and those who didn’t,” he explains. “By doing so, they may discover, for example, that it’s difficult to develop a vaccine for people 55 and older. Or, they may learn that people with obesity are more likely to have an inflammatory reaction.”
Now let’s assess efficacy.
“The vaccine should be 50 to 70 percent effective,” says Don L. Goldenberg, M.D., emeritus professor of medicine at Tufts University School of Medicine and author of the book How the COVID-19 Pandemic is Affecting You and Your Healthcare. “But how is efficacy defined? Most importantly, it’s defined by not getting the virus at all—complete immunity. However, you can also think about efficacy as not having severe symptoms and being hospitalized. I don’t think the vaccine will eliminate coronavirus, but it will decrease the severity and the number of people who get it.”
Every expert interviewed agrees with Goldenberg’s belief that the initial COVID-19 vaccine will not provide complete immunity, but it will decrease the severity. And, they all clarified that it will be too early to predict the long-term effectiveness.
“It’s going take time to know how long the immunity will last and how much immunity is generated with a dose,” says Kesh. “To determine this, we’ll need to give patients the vaccine and then measure their level of neutralizing antibodies in three months, six months, six years, 10 years, etc. That’s how we’ll know how long a person would be protected against reexposure.”
Scientists won’t know the long-term efficacy of the vaccine when it comes to market, so studies will likely continue over time. But according to the FDA’s guidance for potential vaccine manufacturers, the vaccine’s short-term efficacy should be at least 50 percent. Yet because there’s such an urgent need for a vaccine to curb the pandemic, it’s possible that the FDA would issue an approval under the Emergency Use Authorization (EUA), allowing it to approve a vaccine that does have a serious risk or potential for serious risk. If this does occur, it would be because the FDA determined that the “known and potential benefits of a product, when used to diagnose, prevent, or treat serious or life-threatening diseases, outweigh the known and potential risks of the product,” as stated in its guidelines. And, in that case, the FDA would require additional trials after approval to further assess the risk.
Even with that unknown, once you’re confident the vaccine is safe, get vaccinated. If you’re an older adult or cannot avoid group settings/high-risk environments (those in the military, teachers, healthcare providers, etc.), it’s recommended you get vaccinated sooner rather than later. The other priority group is anyone with a high-risk of severe complications from COVID-19. If you’re in that category, you should get vaccinated right away, as long as there aren’t any adverse side effects related to your condition.
And while we’re discussing vaccinations, please get your flu shot.
“Only about 45 percent of the population gets the flu vaccine, and it would be a terrible mistake to not get it this year,” Goldenberg advises. “We don’t want two pandemics occurring simultaneously this winter. Imagine how this would overwhelm hospitals.”
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