What You Need to Know About the COVID Vaccine

From safety to effectiveness, here are answers to your most pressing questions.

History was made on December 11 when the U.S. Food and Drug Administration (FDA) gave emergency use authorization (EUA) for the first COVID-19 vaccine, developed by Pfizer in partnership with BioNTech.

A week later the FDA issued a second EUA for a COVID-19 vaccine from Moderna.

While supplies of both the Pfizer and Moderna vaccines are currently limited, availability is expected to grow as the FDA approves more coronavirus vaccines.

Vaccinating as many people as possible against the novel coronavirus is the best and safest path back to normal life, says Michael G. Ison, MD, professor of medicine and surgery at Northwestern Medicine Feinburg School of Medicine in Chicago. But, he says, “Arriving at that point will involve coordinating many different components, some of which could be quite challenging.”

Here’s what you need to know about the COVID-19 vaccine and how it might affect you.

How do COVID-19 vaccines work?

Unlike traditional vaccines (such as the flu vaccine), Pfizer and Moderna’s COVID-19 vaccines don’t use a weakened or inactivated form of the virus to trigger an immune response.

Instead, both vaccines use a genetic molecule called messenger RNA (mRNA). According to the Centers for Disease Control and Prevention (CDC), instructions contained within the mRNA cause cells in the body to produce a harmless piece of what is called a spike protein — resembling the spike protein on the surface of the coronavirus.

The cells display the protein piece on their surfaces, the CDC explains, prompting an immune response that includes the production of antibodies. These remain in the blood ready to launch a defense against any future coronavirus infection.

How do we know the COVID-19 vaccines are safe?

“Vaccines are studied to look at two things — are they safe and are they effective,” says Dr. Ison. COVID-19 vaccine trials involve tens of thousands of volunteers to assess safety and effectiveness, he says. The final (phase 3) trial of Pfizer’s vaccine enrolled 43,661 participants, according to a release by the company.

To make sure a COVID-19 vaccine is safe, researchers look for common side effects among trial participants, says Ison. “For example, just like with the flu shot, these vaccines cause you to have soreness at the site of the injection and for a day or so afterward you may feel tired and achy; these are recognized risk factors,” he says.

Researchers also assess whether people in the trial become ill, because in rare cases, some types of vaccines can make people sicker instead of less sick, and that’s considered an adverse event, according to Ison. That isn’t the case with the Pfizer and Moderna vaccines, Ison says: If a person gets COVID-19 after being inoculated, they actually get a milder case, which is further evidence of vaccine safety.

Although these large trials offered enough evidence of safety to earn an EUA, one challenge is the very rare events that happen with any vaccine, which may affect 1 in 100,000 people or even one in a million. “That’s why these vaccines will have what’s called post-marketing surveillance,” says Ison.

What is post-marketing surveillance? It means that once the vaccines begin rolling out, public health experts will use a number of measures to identify and track any safety issues, Ison says, adding, “If these are identified, then that will trigger a change in the way the vaccine is given.”

For instance, there have been reports of people having allergic reactions to the Pfizer vaccine, such as tongue swelling and difficulty breathing. All the patients who have had such a reaction so far have been treated and recovered.

Precautions are in place to ensure that people can receive immediate medical attention in the case of a serious allergic reaction. The CDC recommends that people who have a history of anaphylaxis (severe allergic reaction) due to any cause remain under medical observation for 30 minutes after vaccination; everyone else, 15 minutes.

How well do COVID-19 vaccines work?

The Pfizer vaccine is estimated to be 95 percent effective, and the Moderna vaccine 94.1 percent effective.

For a vaccine to be 95 percent effective means that out of every 100 trial volunteers who became infected with the coronavirus in the weeks and months after receiving a shot, 95 were in the group that got a placebo (a saltwater injection) and only five were in the group that got the vaccine, Ison explains. “So all the participants have the same risk of getting infected, but the acquisition of infection is much lower in patients with the vaccine,” Ison says.

The very high efficacy rates of the vaccines was surprising news. The FDA guidance on vaccines, released before the completion of phase 3 trials, stated that any approved vaccine would be expected to prevent disease or decrease its severity in at least 50 percent of the people who are vaccinated.

How long will a person be protected after getting a COVID-19 vaccine?

“It’s going to take time to figure that out — there’s no crystal ball,” says Ison.

The first patient to get a vaccine got their injection about six months ago, he explains, so we don’t know if immunity lasts any longer than that.

Will people have to get the shot every year as with the flu shot?

We don’t know that either, says Ison. People who get a COVID-19 vaccine will be monitored over time, which will help researchers understand how long immunity against the virus will last, according to the Children’s Hospital of Philadelphia (CHOP).

If someone already had COVID-19, will they need a vaccine?

“It’s still recommended that people get a vaccine whether they’ve had COVID-19 in the past or whether they’ve had test to show that they have antibodies,” says Ison. (Antibodies are a sign that a person had COVID-19 in the past and recovered.) That’s because to have protection against COVID-19 you not only have to have antibodies, but you have to have enough antibodies. “What we know is that many people, particularly those who had mild disease, have antibodies, but they are at very low levels, so they may not have enough to fully protect them from reinfection,” says Ison.

Another reason for people who may have had the virus already to get immunized is that there’s evidence to suggest that over time that this antibody level may drop a bit, says Ison. “There’s no downside to getting the vaccine — it will actually boost the responses that the person will already have. Those patients may have even higher antibody responses after the vaccine, giving them a longer duration of protection,” he says.

How long do I need to wait to be vaccinated?

The availability of vaccine is expected to improve over time, but it’s estimated that there will only be anywhere from 5 to 20 million doses available to inoculate people per week for the next several months, according to Ison. “We have 360 million Americans that we need to vaccinate, and each person needs two doses. It’s very easy to do the math and realize that it’s going to take a long time to get people vaccinated,” he says.

The wait also depends on how effective vaccine programs are around the country, says Ison. “Each state and locality is setting up its own system, and so that will probably mean that some areas do it better than others,” he says.

Staffing could also present some challenges. “Health departments are in the middle of the largest peak so far of COVID-19 cases and hospitals are overflowing with patients, and so everyone’s trying to juggle a lot of things,” Ison adds. 

Will children be able to be vaccinated?

The FDA approved the Pfizer vaccine for people who are 16 and older; the Moderna vaccine, for those who are 18 and older.

Vaccine studies involving younger children are due to begin soon. “This is how it generally works in all vaccine development and drug development because if a big problem in adults is observed, you would want to prevent that from happening in more vulnerable children,” Ison says. That means we won’t understand the safety of the vaccine in children for a while longer, he adds. 

Dr. Fauci has stated that vaccine manufacturers and U.S. regulators plan to begin clinical trials in January that will test the safety of the COVID-19 vaccines on young children, according to a report from CNC covering Columbia University’s Grand Rounds 2020 Event in New York City on December 10. A report from NBC November 29 quoted Fauci as saying it would be “months” until a COVID-19 vaccine for children is approved. 

The good news is the virus seems to cause less severe infection in the majority of children. “They can still experience pretty significant disease, and so it is important to protect them, but since the impact on them is less than in the adults and older adult population, the priority for vaccinations is appropriately placed on those higher risk patients,” Ison says.

Is it safe for me to take the COVID vaccine if I’m pregnant?

The American College of Obstetricians and Gynecologists (ACOG) recommends that doctors not withhold the COVID-19 vaccine from individuals who are pregnant or breastfeeding. It’s up to each patient to discuss the risks and benefits of vaccination with their healthcare provider and make a choice.

The COVID-19 vaccines that are currently available haven’t been tested in pregnant volunteers during clinical trials and there is no safety data on use in pregnancy. But Amesh Adalja, MD, a senior scholar at the Johns Hopkins Center for Health Security in Baltimore, says, “I consider it safe to vaccinate pregnant women against COVID-19 because of the biological mechanism of how the current vaccines works and the fact that women became pregnant during the trials, and hundreds of pregnant women have already been vaccinated with no untoward effects.”

Dr. Adalja also points out that pregnant women with symptoms of COVID-19 are at an increased risk of more severe illness compared with nonpregnant women, according to a number of studies.

If you’re pregnant, breastfeeding, or planning to get pregnant, ACOG recommends you educate yourself with all the available data on the safety and efficacy of the vaccine and have a discussion with your healthcare provider. There are a few things to consider when deciding whether to get the vaccine, according to ACOG, including:

  • The level of COVID-19 spread in your community
  • The potential efficacy of the vaccine
  • The risk and potential severity of COVID-19 if you were to get it, including the effects of the disease on the fetus and newborn
  • The safety of the vaccine for you and the fetus

Is it safe for me to take the COVID vaccine if I’m undergoing cancer treatment or have an autoimmune disease?

In general, people who are undergoing cancer treatment can get the COVID-19 vaccine, according to the American Society of Clinical Oncology (ASCO).

Oncologists are accustomed to providing different types of vaccines to people getting all different types of cancer treatment, including chemotherapy, immunotherapy, radiation therapy, and stem cell transplantation, according to ASCO.

In certain cases, people receiving cancer treatment may want to discuss the timing of the vaccine with their doctor, according to Adalja. Appropriate timing could help ensure that the vaccine is going to generate an effective immune response in the context of other treatments that could blunt the response, such as an impending bone marrow transplant, he says.

People who live with chronic conditions that compromise their immunity (such as HIV) or who take medications that suppress their immunity can get the COVID-19 vaccine as long as there are no contraindications (specific reasons for them not to be immunized). Safety and efficacy data on the vaccine for immunocompromised people is limited, but studies have shown these individuals might be at an increased risk for severe COVID-19, according to the CDC, and so more in need of protection from the coronavirus.

The American College of Allergy, Asthma and Immunology states that because the Pfizer and Moderna vaccines are not live vaccines — meaning they don’t contain weakened versions of the live coronavirus — they can be administered to immunocompromised individuals. But the vaccine may not be as effective in these people.

The American College of Rheumatology states that the benefits of the COVID-19 vaccine “are expected to far outweigh any risk from the vaccine.”

What could happen if a large percentage of people don’t get the vaccine?

It’s estimated that between 60 and 80 percent of the population will need to be vaccinated for COVID-19 to achieve herd immunity, according to Ison.

Herd immunity occurs when the vast majority of a population is vaccinated, according to the WHO, lowering the amount of virus in circulation enough to protect vulnerable groups of people who aren’t vaccinated.

Unfortunately a significant precent of people — as many as 40 percent, according to Pew research published December 3 — don’t plan to get a vaccine. “If enough people choose not to get the vaccine, then next year we will be in the same boat as we are today,” Ison says.

I don’t trust vaccines. Isn’t it better just to let our immune system do its job naturally?

“If we were to do it the natural way, which would be letting people get sick, there would be millions of unnecessary deaths due to the infection, as well as challenges to our healthcare system over a very long period of time until we got to that high rate of herd immunity,” says Ison.

With vaccination, you can fight COVID-19 infection in a much more rapid way and do so very safely, without the risk of severe illness or death, he adds.

Can I throw away my mask after I get my shot?

“People will need to continue to wear a mask and maintain social distancing even after they get the vaccine until we get to the threshold for herd immunity,” says Ison.

There are a number of different reasons for this, he says. “Some populations are going to get vaccinated earlier than others. For example, a transplant patient may get vaccinated before their otherwise healthy spouse, and so there would be a risk that others in the household could become infected,” says Ison. It’s also not known whether the vaccine prevents people from being able to spread the virus to other people, according to the Children’s Hospital of Philadelphia.

“Secondly, these vaccines are not 100 percent effective. Even the best vaccines have a 5 percent breakthrough infection rate, and some of the other vaccines that are coming down the pike, the vaccine efficacy isn’t quite 95 percent, so it doesn’t fully protect you against infection,” he says. A breakthrough infection is when a person develops a disease despite having responded to the vaccine, according to the CDC.

“When a large portion of the population is uninfected and there’s still a lot of virus out there, as we’re experiencing now, just because you’ve been vaccinated doesn’t mean that you’re fully protected and can’t get infected,” says Ison.

It’s also important to note that the Pfizer and Moderna vaccines both require two doses, given several weeks apart. “Really, you’re not fully protected until several weeks after the second dose,” Ison says.

Article first appeared on EveryDayHealth

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