Children's Hospital Colorado

COVID-19 Vaccine Approvals: What Comes Next

Patient giving thumbs up after getting vaccine.

This page was updated June 28, 2021. Due to the evolving nature of the pandemic, recommendations can change quickly. Please follow all health and safety guidelines set by your local public health authorities. Reference the Centers for Disease Control and Prevention (CDC) and Colorado Department of Public Health and Environment (CDPHE) for ongoing updates on COVID-19.

When will the COVID-19 vaccines be available for kids? How do we know the vaccines are safe? Our pediatric experts, infectious disease specialist Sean O’Leary, MD, MPH, and Chief Medical Officer David Brumbaugh, MD, break down the latest on the effort to produce safe and effective coronavirus vaccines.

A key milestone: safe and effective vaccine now available for kids 12+

On May 10, the U.S. Food and Drug Administration expanded its emergency authorization of the Pfizer-BioNTech vaccine to include adolescents ages 12 to 15. (Previously, the vaccine had been authorized for people 16 and older.) This eagerly anticipated development marked a key milestone in the pandemic, allowing many more children the chance to be protected from the coronavirus and its emerging variants.

Pfizer’s vaccine trials in children ages 12 to 15 found the vaccine to be 100% effective in preventing COVID-19 among trial participants and with no sign of safety concerns. “The evidence is clear,” says Dr. O’Leary. “Not only is the Pfizer vaccine incredibly effective in kids ages 12 and older, it’s incredibly safe.”

Read Children’s Colorado’s take on the news and why we’re encouraging parents to get their children vaccinated as soon as possible.

According to the Centers for Disease Control and Prevention, more than 5 million adolescents have now received at least one dose of the vaccine. Early data from Moderna’s clinical trials in kids ages 12 to 17 have shown promising results, which means Moderna’s mRNA vaccine may also be authorized for use in everyone ages 12 and older soon.

When can I get a COVID-19 vaccine?

Everyone over the age of 12 is now eligible to receive the COVID-19 vaccine in the U.S. State and federal agencies are working as quickly as possible to deliver vaccines to anyone who wants one, and the pace so far has been impressive  –  half of all U.S. adults are now fully vaccinated. That’s zero to 50% in less than six months. 

Even better news? Based in large part to this vaccination effort, cases of COVID-19 are falling across the country.

When will younger kids be vaccinated?

The emergency use authorization for Pfizer’s vaccine in kids 12 and older marks a key milestone in responding to the pandemic. But kids younger than 12 still need to wait.

Children younger than 12 are not likely to get the vaccine for some months. Medical experts are projecting that the earliest younger kids will become eligible is sometime in the fall of 2021.

Why it’s taking longer for kids

It’s important that COVID vaccines are studied in kids before using them widely. There are good reasons for studying kids separately from adults and for studying kids after adults.

One is that kids are at far lower risk for serious complications of COVID-19 than adults, particularly older adults. Many kids who get COVID-19 never even have symptoms. Additionally, kids’ bodies are different, and they may react differently to a vaccine than adults do. But things are moving. Over the next few months, Children’s Colorado will participate in a clinical trial investigating the safety and immune response of the Pfizer vaccine in kids ages 5 to 11.

In the meantime, Drs. Brumbaugh and O’Leary encourage families to be patient while waiting for a safe and effective vaccine for younger kids. While we wait, parents should make sure that the whole family is taking precautions to prevent COVID-19, including masks and social distancing, and receives a flu shot when they become available again in the fall.

Wondering what you can do when some of the family is vaccinated but younger kids are not? Find our tips on safe summer activities for unvaccinated kids.

Which vaccines are available?

So far, the Food and Drug Administration has given emergency authorization to three vaccines for COVID-19. The first came from pharmaceutical-makers Pfizer and BioNTech, and a second from Moderna followed closely behind. Both of those first vaccines are based on a technology known as mRNA. Both also require two doses, an initial shot and a booster 3 to 4 weeks later, to be fully effective. 

In early 2021, the FDA issued emergency authorization for a third vaccine from the pharmaceutical company Johnson & Johnson (Janssens). In mid-April, the FDA and CDC paused distribution of the Johnson & Johnson vaccine temporarily while they investigated a potential link to a very rare blood clotting condition. After careful review, the agencies resumed their recommendation of the Johnson & Johnson vaccine with additional guidelines for women younger than 50 years. As of April 23, vaccinations with Johnson & Johnson’s COVID vaccine have restarted with this addition (more on this below).

Unlike the Moderna and Pfizer vaccines, the Johnson & Johnson vaccine can be stored more easily and only requires one dose, rather than the two doses the Moderna and Pfizer vaccines require.

What do they mean by effective?

Clinical trials showed the mRNA-based Pfizer and Moderna vaccines to be more than 90% effective. The Johnson & Johnson vaccine was shown to be 66% effective worldwide, although that figure increased to 72% in the U.S.

It’s important to remember that the term “effective” refers to the vaccines’ ability to prevent all symptomatic infections. But even in cases where someone got sick, all three vaccines were still 100% effective against severe infection, including hospitalization and death. 

Why was the Johnson & Johnson vaccine paused? Should I be worried about that?

Currently, all three vaccines are available under “emergency authorization,” which is a little different than approval. And it’s an important distinction because it reflects the urgency of the pandemic. Not quite as much is known about these vaccines as would ordinarily be known about a drug before approval, particularly their long-term effects. So medical experts and agencies like the FDA and the CDC want to be cautious. 

That’s essentially why authorities chose to pause distribution of the Johnson & Johnson vaccine after the CDC’s alert system identified a rare clotting disorder in a small number of women in the weeks after they received the vaccine.

“In some ways it was an indication that the system is working right,” says Dr. Brumbaugh, “because it gives us the opportunity to see this cluster of cases and understand what happened.”

During the proactive pause, investigators compared the rate at which this clotting disorder occurs in people who received the vaccine versus people who didn’t; they concluded that this adverse event is associated with the Johnson & Johnson vaccine but remains very rare, occurring at a rate of about 7 per 1 million vaccinated women between the ages of 18 and 49. This adverse event is even more rare for women 50 years and older and men of all ages. 

“It takes a lot of hours and data crunching to be able to make that determination,” Dr. Brumbaugh says. 

What you need to know about the Johnson and Johnson vaccine

The agencies have since updated their vaccine safety guidelines for this subgroup of adults. Women younger than 50 years old should be aware of the rare but increased risk of blood clots with low platelets after vaccination and that this risk has not been seen with the Pfizer and Moderna vaccines. If you have questions about your risk and which vaccine you should get, talk to your doctor.

If you have received (or will receive) the Johnson & Johnson COVID-19 vaccine, three weeks after receiving the vaccine, you should be on the lookout for possible symptoms of a blood clot with low platelets. The CDC has updated details on the Johnson & Johnson vaccine.

Should we expect additional pauses?

It’s possible. COVID-19 vaccine safety is a top priority for the government, and reports of health problems following COVID-19 vaccination are taken very seriously. 

If you experience any adverse events after any vaccination, report them to v-safe and the Vaccine Adverse Event Reporting System (VAERS). Learn about how vaccine safety systems work.

How we got here

Operation Warp Speed and the successful push for a safe and effective vaccine

Vaccines are a risky proposition for pharmaceutical companies. Only about one in 10 vaccines in development is likely to produce a viable result, and they take a long time to develop. The quickest before COVID-19 took about four years. Most take closer to 10 or 15.

Operation Warp Speed was the U.S. Department of Health and Human Service’s attempt to shatter that timeline, basically by paying six different pharmaceutical companies to give it their best shot – ideally bringing a vaccine to market within a year.

“It’s unprecedented,” says Dr. O’Leary.

A pediatric infectious disease specialist at Children’s Colorado, Dr. O’Leary has himself played an outsized role in the scientific community’s response to the pandemic, as a representative of the American Academy of Pediatrics. He also played a role in CDC committee that approved and made recommendations on the current available vaccines.

How did the vaccine development happen so fast?

It happened fast for two basic reasons. One was funding. Vaccines cost a lot of money to develop, and because so many of them fail, drug-makers take on a lot of risk developing them. Operation Warp Speed absorbed that risk by paying pharmaceutical companies up front. The U.S. government spent tens of billions of dollars in the hope of helping produce at least one viable vaccine, and hopefully more. The effort paid off.

The other reason was efficiency. It takes a lot of people and organizations to develop and produce a vaccine, and typically, the process involves a lot of waiting: for funding, for supplies, for review processes, and so on. In Operation Warp Speed, the whole process was streamlined. 

A pharmaceutical company would also typically wait to see if their vaccine was approved and recommended before beginning to manufacture. Operation Warp Speed, however, paid companies to manufacture their vaccines before it was known if they’d work. So once they were authorized, they were ready to go immediately. Even then, doses are in short supply. But as long as the timeline currently is, it would be a lot longer if Pfizer and Moderna were only starting to ramp up manufacturing now.

To better understand that timeline, it helps to understand what’s happened so far.

What it takes to develop a vaccine

At the most basic level, a virus is really just a tiny wad of genetic code. It gets into the body, attaches to cells and essentially highjacks their mechanisms to reproduce itself. In response, ideally, the immune system makes antibodies that kill the virus off. But in the meantime, the virus can do a lot of damage. 

The idea of a vaccine is to prevent the virus from infecting the body in the first place. Vaccines more or less train the body to kill a virus as soon as it comes along, before it does. It’s a complicated process that typically starts with understanding as much as possible about how, specifically, the virus works in bodies. How does it get into cells? How does the immune system react to it?

In the case of COVID-19, there’s a lot scientists still haven’t figured out. For example, multisystem inflammatory syndrome in children, or MIS-C, a dangerous condition that COVID-19 causes in a small number of kids, is probably related to immune response. But scientists don’t know exactly how or why.

On the other hand, there is also a lot that medical experts do understand about this virus, and we’re learning more every day. For example, we knew the genetic code of this virus in January 2020, before many people had even heard of COVID-19. The speed of development, says Dr. O’Leary, speaks to the decades of research on vaccines in general and on coronaviruses specifically that have led us to this moment.

How do clinical trials work?

Viral infection is a molecular process, so once a pharmaceutical developer has a handle on the chemistry, the next step is to test the biology in animals. Both those steps generally take years. But if a vaccine, after much testing, does look safe and effective, eventually it makes the leap to testing in humans.

Those tests are called clinical trials, and they happen in three phases.

Phase one

The big question in phase one is, “Is it safe?” Phase one trials typically involve a small group of people. If the treatment is shown to have harmful effects, the testing ends and everyone goes back to the drawing board.

Phase two

Phase two often involves a randomized control trial, where participants are usually divided into two groups: one gets the treatment being tested; another gets a placebo, or dummy drug. In this phase, researchers are building a better understanding of the treatment’s safety, as well as how and if it works. In the case of vaccines, one of the big questions in phase two trials is if the vaccine generates enough immune response to be effective.

Phase three

The final phase involves the largest group of people, often in the thousands or tens of thousands. This phase seeks to answer, “How effective is it, and how does it work best?” Researchers study how the drug works on people of different ages and medical histories, comparing different doses and frequencies. In the case of a COVID-19 vaccine, the Food and Drug Administration (FDA) has stated it would approve a vaccine that protects against the virus in at least 50% of people who get it. As with earlier phases, safety remains of paramount concern.

How does a new vaccine get approved?

The FDA: approval

If a potential treatment is shown through clinical trials to be safe and effective, the pharmaceutical company then submits all their trial data to the FDA. The FDA reviews the data and decides whether to approve the treatment — meaning it decides whether the company can sell the treatment to the public. This process alone typically takes at least a year.

In addition to internal review by staff at the FDA, the FDA also has an external group of experts called the Vaccines and Related Biological Products Advisory Committee, or VRBPAC for short. The committee consists of 15 outside experts in virology, epidemiology, biostatistics, microbiology and about a dozen other related disciplines. All of its members are thoroughly vetted for potential conflicts of interest and are not beholden to political interests. In general, without the VRBPAC approval, the FDA doesn’t approve.

The CDC: recommendation

If the FDA approves of a new vaccine, it then goes to the CDC, which decides whether to recommend it in the U.S., and for whom. This step is an important one for vaccines, since healthcare plans are required to cover vaccines with no deductible under the Affordable Care Act. That coverage doesn’t happen without a CDC recommendation.

Like the FDA, the CDC has a review process conducted by a panel of vetted outside experts removed from political pressure, this one called the Advisory Committee on Immunization Practices, or ACIP. That’s the one Dr. O’Leary is a part of, as a representative of the American Academy of Pediatrics and the Pediatric Infectious Diseases Society. Their meetings are free and open to the public, if you’re so inclined.

The Pfizer, Moderna and Johnson & Johnson have already gone through that entire rigorous process — and any other vaccines that might be approved in the future will go through it too.

How do mRNA vaccines work?

Both Pfizer’s and Moderna’s vaccines employ a technology called messenger RNA. Where traditional vaccines have generally used inactivated parts of the infectious virus to prime the immune system to respond to it, messenger RNA, or mRNA, actually tells cells what to build inside themselves. The vaccination works essentially by introducing a bit of code that tells cells how to protect themselves against a virus.

The advantage of mRNA vaccines is that they’re faster and cheaper to produce. And since they aren’t made using infectious elements, they’re potentially safer for patients. The possible downside? Vaccines employing mRNA may need to be stored at incredibly cold temperatures — close to 100 degrees below zero, Fahrenheit — which has presented logistical challenges when it comes to distribution.

Pfizer’s vaccine was the first mRNA-based treatment ever authorized, and Moderna’s was the second.

Do I need to get vaccinated if I’ve already had COVID-19?

The clinical trials from all three vaccines showed that they’re safe for people who have already had COVID-19, so the current thinking is that people should get vaccinated, when possible, regardless of whether they’ve had it or not, although it should wait until they’ve recovered. (If someone were to get it after their first vaccine dose while waiting for the second, they should wait until after they’ve recovered to get the second one.)

That said, the most up-to-date evidence also suggests that reinfection is uncommon for about 90 days after the initial infection, so people might wait to get vaccinated until near the end of that period — if they want to.

Are these COVID-19 vaccines safe?

Vaccines have historically been remarkably safe and effective, and Dr. O’Leary believes all three currently available vaccines — along with any other vaccines that might be authorized — are no different.

That’s because, although the process has been accelerated, no corners are being cut. All three vaccines went through every single step of the vast, rigorous and complex process required to understand the safety and effectiveness of any new vaccine.

"This didn’t just happen in a year. This work is built on decades of remarkable progress in the development of vaccines,” says Dr. O’Leary. “I think we have many reasons to trust the process."

That goes not just for COVID-19 vaccines, but for the many other vaccines available. Dr. O’Leary notes that vaccination rates for kids have recently declined, potentially because families are avoiding healthcare providers’ offices due to the pandemic.

That would be a mistake, Dr. O’Leary says. Vaccines are the single best way to prevent disease: Kids need them to stay safe. That’s especially true this year, when COVID-19 has the potential to complicate other diseases in ways that are difficult to anticipate — including influenza. Dr. O’Leary urges families to make sure kids get their flu shot as soon as they become available.

As for the COVID-19 vaccines, it may be a while before they’re available for all ages. And the pandemic isn’t over. COVID-19 is still spreading, particularly in areas with low vaccination rates. Until you are fully vaccinated (2 weeks after your last dose), there’s still every reason to take precautions like social distancing and wearing masks.

But there’s a light at the end of the tunnel now, and that’s a lot better than the alternative.

“I’m optimistic,” Dr. O’Leary says.

Trustworthy sources on the COVID-19 vaccines


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