Curious About the New COVID-19 Vaccines? We've Got Answers

The news is super exciting, but there are still a lot of questions about how the new shots work. Here's what we know now.

by Sarah Ellis Health Writer

It’s probably fair to say that everyone has experienced COVID-19 burnout by this point. Nine months since quarantines first began, and the coronavirus pandemic is nowhere near over—in fact, case numbers in the U.S. are the highest they’ve ever been. So, what’s keeping us going these days? The assurance that this won’t last forever, and the hope that a forthcoming vaccine will allow us to return to normal again.

The good news: The elusive COVID-19 vaccine is getting closer to becoming a reality. In early November, two major pharmaceutical companies—Pfizer and Moderna—announced preliminary results from clinical trials of their COVID-19 vaccine candidates. The results suggest that these vaccines may be 95% effective at preventing illness from COVID-19.

Then, on Nov. 23, AstraZeneca became the third pharmaceutical company to release (somewhat confusing) efficacy results for a COVID vaccine candidate. Its vaccine, produced in partnership with Oxford University, was tested in two different dosing regimens—the first was accidentally (but, as it turns out, advantageously) given as a half-dose, followed by a full dose one month later. When researchers realized they'd dosed by half the first go-round, they did another regimen, this time giving two full doses one month apart. Turns out, the "mistaken" half-dose regimen is 90% effective, while the full-dose regimen is only 62% effective. No one yet knows why, although researchers theorize the half-dose may better mimic a natural infection, triggering the best immune response.

So, this is all promising stuff. The not-so-good news? Many of us are left with more questions than answers. When will the vaccine be available to the public? How will we know it’s safe? What happens to the unlucky minority who are vaccinated but still go on to develop symptoms? We tapped two top infectious disease experts to address these burning questions and help put your mind at ease.

1. How close are we to a COVID-19 vaccine becoming widely available?

We’re getting close—but not as close as some recent headlines might suggest. Rashid Chotani, M.D., medical director and senior scientist at IEM in Morrisville, NC, estimates that the general population won’t have access to an approved vaccine until the end of the first quarter, or perhaps even the second quarter, of 2021. The reason for this has to do with the drawn-out authorization and rollout process.

“We’ve been looking forward to having a vaccine for some time. We’ve been saying sometime in 2021, and I think that’s still correct,” adds Helen Boucher, M.D., chief of geographic medicine and infectious diseases at Tufts Medical Center in Boston. She explains that although a vaccine may receive authorization from the Food and Drug Administration (FDA) by the end of the calendar year 2020, it could still be many months before most of the population can actually get vaccinated.

Here’s what the next steps look like: Both Pfizer and Moderna plan to submit their vaccines for Emergency Use Authorization by the FDA in the coming weeks. Then, Dr. Boucher explains, the FDA will convene an advisory committee composed of infectious disease experts called the Vaccines and Related Biological Products Advisory Committee (VRBPAC), which will review the data and make an official recommendation to the FDA. From there, the Centers for Disease Control and Prevention (CDC) will convene their own advisory committee, called the Advisory Committee on Immunization Practices (ACIP) to make their own recommendations about when and exactly how the vaccine should be administered among different populations.

“All those steps need to happen, and [when] they do, then people like me and many other infectious disease experts will line up for the vaccine,” Dr. Boucher says. Just don’t expect rollout to happen immediately. Again, we’re talking April 2021—at the earliest.

The National Academies of Sciences, Engineering, and Medicine

2. Who will get the vaccine first, and where will they go to get it?

In September, the National Academy of Medicine (NAM) proposed a four-phase approach to rolling out the COVID-19 vaccine to maximize benefit to at-risk populations. “The first phase [of distribution] would be for high-risk healthcare workers,” Dr. Boucher explains, such as doctors and nurses in COVID hospital units, ambulance drivers, and EMTs. From there, the vaccine would likely be distributed to older adults in congregate living spaces and people with underlying medical conditions, as well as K-12 teachers and staff. Then, the focus would turn to essential workers such as transportation and food production workers, as well as to children and young adults, according to the NAM plan. “The devil will be in the details,” she says. “I think as we go forward and as the vaccines go through the review process, the CDC will probably make recommendations that are a little bit more granular.”

One major hurdle to distribution right now is the logistics of vaccine transportation. Both Pfizer and Moderna’s candidates must be refrigerated from the moment they’re made to the moment they’re administered. "The Pfizer vaccine requires a very cold freezer that not everybody has, so the transportation and storage is complicated,” Dr. Boucher explains. (We’re talking -70°F.) “People like me in our hospital systems are hard at work planning for how we can vaccinate large numbers of people with these particular products.” Moderna’s alternative candidate, on the other hand, can be stored in a regular freezer at -20°F, something to which most hospitals, clinics, and even chain store pharmacies already have access. (That might make it possible to get the vaccine at your local CVS, for example.)

3. Will the vaccine be administered in two doses?

The three leading candidates are all two-dose vaccines, meaning you’ll have to get stuck with a needle twice. (Sorry in advance for the folks out there who hate getting their shots.) The first day, you’ll get a shot, and then you’ll come back a designated number of days later for the second dose. Pfizer’s is a 21-day window, Moderna’s is a 28-day window, and AstraZeneca’s is at least one month. The second shot, given within the right timeframe, is essentially a booster ensuring that immunity kicks in and that it lasts—and imperative to do with all three vaxes. “That’s what’s required to get enough of an immune response to be protective,” Dr. Boucher explains. “We don’t consider anyone protected until two weeks after the second dose. The immune system has to do its job so it can recognize the virus and block it.”

This two-dose model presents a logistical challenge. “You will have to do it exactly how it’s authorized,” Dr. Boucher says—otherwise, it might not be as effective. “The FDA will authorize it and ultimately license it according to how it was studied.” So, we can't underscore this enough: You’ll have to go back to the doctor exactly three or four weeks later.

But, that’s not all. You must get two doses of the identical vaccine, no matter how many effective vax candidates become available. Why? Because “each vaccine is studied separately,” Dr. Boucher explains. “So, if you were to get one, that’s the one you get two doses of.” It’s unclear for now what would happen if you mixed up the doses, but it could potentially lower the efficacy, so it’s best to stick with what researchers already know. Of course, only time will tell if a one-dose vaccine prevails—Janssen, another company in Phase III trials, is working on one right now, but has not yet released preliminary results about its effectiveness.

Dr. Boucher notes that doctors and hospitals across the country are already prepping to administer vaccines on a wide scale. “We’re all involved in planning, preparing, figuring out freezers, who’s going to give it, how we’re going to track it, and all these different issues so we’re ready and able to proceed when there is a vaccine,” she says. The goal is to make the process as seamless as possible.

4. Should people with pre-existing health conditions (or anyone, really) be concerned about side effects?

Safety is top-of-mind for everyone, and for good reason—the last thing you want is to get sick from a shot after months of staying isolated to minimize your risk. Ultimately, it will be up to governmental regulatory bodies to ensure that protocol is followed to a T. “I have confidence in the FDA and the oversight bodies such as ACIP and National Academy of Medicine and the scientists working on the vaccines not to authorize any vaccine that might cause adverse effects in any strata of the U.S. population,” Dr. Chotani affirms.

Unfortunately, immunocompromised people weren’t included in the first round of clinical trials, so there is currently no data to show how the vax works in this population. The theory is that because mRNA vaccines contain no traces of live virus, they should be safer than some traditional vaccines—but again, that hasn’t been proven yet. Of course, it’s also important to note that folks with pre-existing health conditions are also among the highest-risk groups for serious COVID-19 infection, so the shot could ultimately help keep them safer. If you’re immunocompromised and worried about getting the shot, have a conversation with your doctor first to discuss potential risks and benefits.

So far, several participants in COVID vaccine trials have spoken out about experiencing body aches, high fevers, and chills in the day or two after being inoculated with either Pfizer or Moderna’s vaccine candidate—similar or somewhat worse than what some people feel after getting the flu shot. To be clear: This does not mean they became ill from COVID-19 as a result of the vaccine, nor does it mean you’ll get seriously ill if you get vaccinated. Temporary, often low-grade symptoms like those reported post-vax are merely a sign that the body’s immune response is doing its job and building immunity on its own.

5. If a vaccine is 95% effective, what does that mean for the other 5% of people?

According to preliminary data, Pfizer now reports that its vaccine, originally touted as being 90% effective at preventing illness from COVID-19, is actually 95% effective after furthing testing revealed updated (although not yet peer-reviewed) results. Meanwhile, Moderna's vax candidate shares similar efficacy against COVID-19 at 94.5%. Those ratings sound pretty great…for everyone except the unlucky outliers. (At least for now, who, exactly, the outliers will be remains unclear.) But it’s important to remember that no vaccine is 100% effective in every person, all the time. (The annual flu shot is about 50% effective, to offer some perspective.) “The goal is for vaccine-associated herd immunity,” Dr. Boucher says. “We need to get enough of the population immune to this virus so that it won’t continue to spread.”

Herd immunity is a term used by epidemiologists to describe the point at which a virus can no longer spread in a community because a large percentage of the population is immune. Experts estimate that 60% to 70% of the population will need to develop immunity—either through infection or vaccination—for COVID-19 to stop spreading. This makes everyone in the community safer, including those for whom the vaccine didn’t work as well. “The 5% who do not develop immunity will be at a much lower risk of acquiring the disease [once herd immunity is established], as the virus will not be in circulation [like] it is now,” Dr. Chotani explains. Luckily, though, clinical trials are revealing that those who got sick after getting vaccinated experienced milder symptoms from the illness. So, if you do come down with COVID-19 after getting the vaccine, you’re less likely to have a serious case.

Responsibility for protecting public health falls on all of us. “We can’t change our behavior and stop wearing masks, washing our hands, and avoiding crowds just because we get vaccinated,” Dr. Boucher warns. “We have to wait until we achieve that herd immunity that makes the virus stop spreading.” Just like you wear a mask to protect others, getting vaccinated is a way to contribute to the greater good—and to get us all out of quarantine more quickly.

6. What happens if many people refuse to take the vaccine?

There’s also the concern that misinformation or vaccine skepticism could lead to a widespread unwillingness to get a COVID vaccine once it’s offered. Gallup poll data from October 2020 shows that 58% of Americans say they would be willing to get the vaccine if given the chance; that’s up from 50% in late September.
The fewer people opt into the vaccine, the more difficult it will be to eradicate this virus, Dr. Boucher says. “What that means scientifically is that it will take longer to achieve herd immunity. And if nobody wants to take the vaccine, we’ll be stuck, because we need to have immunity in about 60% of the population to stop the transmission of this virus.”

To counter this, Dr. Boucher sees it as her responsibility to communicate the science clearly. “My job as an infectious disease doctor is to be truthful, clear, and available about the information as it comes out, so people trust the data on the safety and effectiveness,” she explains. “As long as this process proceeds as it should with no shortcuts—which is the promise, and how everything’s going—and we get to the other side, then it’s going to be [up to] people like me and other infectious disease doctors to communicate very efficiently, clearly, and with empathy.”

7. Is the COVID vaccine safe to get during pregnancy?

The research on COVID-19 and pregnancy is still in early stages and continues to develop. Mary Jane Minkin, M.D., OB/GYN and clinical professor at the Yale University School of Medicine in New Haven, CT, breaks down what we know so far: “As of the moment, it is felt that pregnant women may get sicker than non-pregnant women if infected with COVID,” she says. Research shows that pregnant women with COVID-19 may be more likely to give birth prematurely, and those with comorbidities (like diabetes and high blood pressure) are at even higher risk. Luckily, though, “most studies show a small risk of transmission to the baby,” she notes.

There’s also a lack of research on the safety of COVID vaccines given during pregnancy. “Thus far, the studies have not included pregnant women,” Dr. Minkin says, “so we will need to see data on pregnant women before the vaccine is widely recommended for them.” Those currently trying to get pregnant have less to worry about. “For women who are thinking about pregnancy, most experts on the vaccine believe it should be safe for those women,” she notes, “but again, we do need more data.” Talk to your doctor if you are concerned for your health or the health of your baby.

This issue further emphasizes the need for everyone to do their part to keep others safe—and that means getting the vaccine if you’re in a group it has been deemed safe for. “The more folks around our pregnant women who get vaccinated, the better,” Dr. Minkin says. “The vaccines will benefit pregnant women no matter what, even in an indirect fashion.”

8. How long will vaccine-induced immunity last?

“That’s an unknown at this time,” Dr. Boucher says. Experts won’t definitively know the length of immunity until they have followed vaccine recipients for, well, years. One study in The Lancet speculated that the duration of COVID vaccine-induced protection might last for less than a year, meaning this could end up being like the flu vaccine you get every fall. It depends on many factors, like how well the vaccine works and how long the human body maintains antibodies to fight COVID-19. For now, we just don’t know the answers.

9. How long after a vaccine is introduced will we still need to wear masks and practice social distancing?

Unfortunately, getting vaccinated doesn’t automatically clear you for a return to normal life. “It will take a while [for a vaccine] to reach all the U.S. population,” Dr. Chotani says. “I believe that it will take a year or longer to be at a stage where we might develop herd immunity, and in 2022 we might return to somewhat normal life.” Yep, that’s right—you’ll be masking up and practicing smart social distancing for at least another year.

That sounds like a long time, but let’s focus on the positive. “There are a lot of things that are changing and that, I think, will come together to make 2021 a better year,” Dr. Boucher says. The COVID death rate has decreased dramatically since March—though it is trending up again in some states and counties as case numbers rise. The general decrease in mortality, however, is thanks to better testing, new drug therapies, and a clearer understanding of how to flatten the curve. If the 95+% effectiveness rate on vaccines bears out, this could get us to herd immunity within a matter of months—but only if a majority of people actually take the vaccine, which remains to be seen.

What’s important to focus on right now is getting through the winter without giving up on crucial safety measures: wearing masks, maintaining physical distance, washing hands, and not going to work (if possible) or mingling in groups of people, especially indoors, if you have symptoms. “We know this works,” Dr. Boucher says. “It’s hard work, but it works. And that’s the tool we have right now.” That might mean you need to skip out on holiday travel this year.

We’re not out of the woods yet, but we might be approaching, well, the beginning of the end. “This is perhaps the first time in our history that a vaccine will be approved during a pandemic—a great scientific feat,” says Dr. Chotani. Better days are definitely coming, but for now, let’s all keep doing our part: Mask up, stay home, and count the days until we can line up to get our shots.

Sarah Ellis
Meet Our Writer
Sarah Ellis

Sarah Ellis is a wellness and culture writer who covers everything from contraceptive access to chronic health conditions to fitness trends. She is originally from Nashville, Tennessee and currently resides in NYC. She has written for Elite Daily, Greatist, mindbodygreen and others. When she’s not writing, Sarah loves distance running, vegan food, and getting the most out of her library card.