Every Covid-19 Vaccine Question You’ll Ever Have, Answered
By: Tara Haelle
Tags: Covid 19, Coronavirus, Vaccines, Health, Science

Safety

Q: How will I know if the vaccine is really safe?

It’s not surprising that many people have questions or uncertainty about getting a Covid-19 vaccine. “It’s entirely reasonable to have doubts and concerns,” Greyson said. “We tell people to question interventions, especially new ones, and this is an intervention, and it’s a new one.”

Further, the speed at which these vaccines were developed is “amazing but understandably can be scary if we don’t understand how they were done faster,” Greyson said. “Usually when we talk about things going fast, they’re rushed, we skip steps. In this situation, that’s not the case, but that hasn’t been effectively communicated to the public.”

Here’s how we can know steps were not skipped with these vaccines: Every expert on the planet can review the data themselves. In addition to the two committees of independent experts who will review the vaccine data — VRBPAC at the FDA and ACIP at the CDC — all the clinical trial data submitted to the FDA and CDC will be made available to the public. Pfizer’s data went public December 8 — a whopping 92 pages of it. Other experts can read it and raise any red flags they come across. If you don’t know which experts to follow, Omer has a simple rule of thumb: “Do what Fauci says. He’s a shorthand for outside experts.”

Since other countries are reviewing data for the same vaccines, those who don’t feel confident about the FDA or CDC can look to regulatory agencies overseas for their verdicts on the vaccines’ safety.

Q: What kinds of side effects could the vaccine have?

All vaccines can have reactions and side effects. Side effects are unexpected responses to the vaccine that are uncomfortable or painful but are usually rare. Reactions, especially soreness, swelling, or redness at the injection site, are much more common and are expected to occur in some people after vaccination. Other reactions reported from Covid-19 vaccines include headache, nausea, muscle stiffness, soreness, and aches — all of which are common with many vaccines.

“These are not really side effects in the way that we think about them,” Brewer said. “These are routine reactions that your body has.”

Reactions typically occur because of the way vaccines work — by stimulating the immune system. Illness symptoms like coughing, sneezing, fever, runny nose, and watery eyes are actually the immune system’s response to a pathogen, trying to get rid of it. A fever occurs when the body heats up to help the immune system work more efficiently. Coughing and sneezing are the body’s attempts to literally eject intruders from your body.

Therefore, when these symptoms occur after a vaccine, it’s most often because the vaccine worked (though not necessarily always, as these reactions can occur in placebo groups as well). That is, the vaccine caught the immune system’s attention, and the immune system got to work defending against what it thinks is the real virus.

“The immune response needs a better public relations team because this is just what happens when you respond to a foreign protein, the SARS-CoV-2 spike protein,” that the vaccines cause your cells to produce, Offit said. “When you respond to a natural infection or you respond to an immunization, your immune system makes a series of proteins that cause side effects. That means you’re having a vigorous immune response.”

So while these reactions aren’t pleasant for many—and downright miserable for some—the good news is that they usually mean your immune system is working well. It’s also why many people feel tired or worn out for a few days after getting a vaccine: Your body used up a lot of energy fighting a serious threat (or so the immune system believed it to be).

Most people experienced only mild or moderate reactions, if any, from the Moderna vaccine, but the company hasn’t yet released its complete data on side effects, so it cannot be compared to the Pfizer vaccine right now. Moderna did report numbers for severe adverse events: about 2% developed high fevers (102ºF–104ºF) and severe chills. Other severe Moderna vaccine reactions included severe fatigue (10% of participants), muscle pain (9%), joint pain (5%), and headache (5%). Likely a much higher percentage experienced mild or moderate versions of those side effects, but we won’t know until the company releases the full data.

With the Pfizer vaccine, the younger participants were, the more commonly they reported similar reactions: fatigue, headache, muscle pain, chills, joint pain, and fever. Among the small data set of 100 adolescents aged 12–15, for example, 14% experienced a fever after the first dose, and 20% experienced one after the second dose, compared to 1% and 11% in older adults (over age 55). It‘s not necessarily surprising that older adults would experience fewer reactions than younger people since reactions usually result from how strongly the immune system responds; the older you get, the less efficiently your immune system responds to threats.

The most commonly reported adverse events with the Pfizer vaccine were headache (42% of participants with the first dose and 52% with the second) and fatigue (27% and 59%), which also occurred in the placebo group, though at lower rates. One common theme that occurred across all ages was a stronger reaction to the second Pfizer dose than the first. A majority of participants reported pain at the injection site with both doses. But more than half of participants of all ages felt fatigued after the second dose, and high numbers experienced headaches as well. In those aged 16–55, more than a third experienced chills and/or muscle pain, and the numbers were only slightly lower in those over age 55. A small proportion of participants (less than 1%) experienced severe fatigue, headache, muscle pain, joint pain, or fever with the first dose, and only slightly more (2% or less) had these severe reactions with the second dose, except 3.8% who had severe fatigue with the second dose.

The adverse reactions reported in the AstraZeneca vaccine trials are similar—fever, chills, fatigue, headache, muscle aches, nausea, joint pain, or generally feeling crummy—though complete phase 3 data are not available yet. One severe adverse event occurred in the AstraZeneca trial: a person developed transverse myelitis (an inflammation of the spinal cord) 2 weeks after getting the second dose, though researchers could not determine if it was related to the vaccine or not. The person recovered and remained in the trial. Not enough data from other vaccine candidates are available yet, but they’re likely to be similar unless an unexpected adverse event is found.

If you get a Covid-19 vaccine, odds are high that you’ll have a sore arm. In addition, some people will have severe swelling at the injection site, and others will feel knocked flat for a day or two, as though they’ve gotten sick, especially after the second dose of an mRNA vaccine. They haven’t gotten sick or been given Covid, but their immune system doesn’t realize that and has gone into overdrive to protect the body. It’s helpful to be prepared in case you’re among the unlucky ones who has a severe reaction, but know that it passes within 1–3 days. Some experts recommend that people plan for stronger reactions to the second dose by getting it on a Friday or taking off work the next day.

So far, none of the vaccines have shown more serious reactions or side effects than these in the trials, but two people in the United Kingdom did experience severe allergic reactions after receiving the Pfizer vaccine. (See the next question.) Researchers will continue to look for adverse events in trial participants for several years, and the CDC has several surveillance systems to look for and respond to vaccine safety concerns in the general public.

Q: After the severe allergic reactions seen in two U.K. vaccine recipients, should I avoid the vaccine if I’ve ever had a severe allergic reaction to anything?

Early in the Pfizer vaccination program in the U.K., two people experienced serious allergic reactions after receiving the vaccine. Both recovered, and both had a previous history of serious allergies that led them to carry adrenaline shots (EpiPens). U.K. regulators have since suggested that others with a history of serious allergic reactions should not get the vaccine, but that broad recommendation may be premature, explained Offit.

“I think that was an unfortunate move on the U.K.’s part because I think it just scared people unnecessarily,” Offit said. “I think it would have been more reasonable to actually look a little more carefully at those two patients to see what component, if any, in that vaccine caused an allergic reaction.”

Hopefully, scientists in the U.K. are investigating those reactions further, and the U.K. authorities may revise their recommendation after learning more. After the vaccines receive approval in the U.S., the CDC’s ACIP committee will include in its recommendations which groups should not get the vaccine.

Q: What about long-term side effects that we don’t know about yet?

It’s rare for a vaccine to have any side effects more than two weeks after getting it, but there are a few instances that have occurred with past vaccines. The 1976 swine flu vaccine had an increased risk of Guillain-Barré syndrome (GBS), a nerve disorder (one case per 100,000 people vaccinated). The seasonal flu vaccine has been linked to a small increased risk of GBS as well some years, but it’s in the neighborhood of one or two cases per million, and the risk of GBS from influenza infection is several times higher. Another example is the rotavirus vaccine, which was linked to a very slight increased risk of intussusception, a bowel problem that sometimes requires surgery to treat. One of the H1N1 flu vaccines distributed exclusively in Europe had an added ingredient to enhance the immune system, called an adjuvant, that was linked to increased risk of narcolepsy.

All of these longer-term, rarer side effects occurred within a few months of the vaccine and were picked up quickly by vaccine safety surveillance systems. Many of the mRNA trial participants have already been vaccinated for up to four months. No U.S.-approved vaccine has shown serious long-term effects more than a few months after vaccination, and it’s difficult to determine a biological reason that might happen. Companies needed at least two months of follow-up to apply for an EUA from the FDA, and by the time a vaccine is available for you, many more months will have passed when researchers gathered more data.

It’s valid and reasonable to have questions about possible long-term effects that occur several months after a Covid-19 vaccine, so researchers and regulatory officials are closely monitoring vaccine recipients to look for any. Continue to follow the news as the vaccines roll out to find out if any long-term effects get reported, but based on the history of vaccines in general, it’s not likely they will.

Q: Are there any medications that would interact with a Covid-19 vaccine?

In the data reported thus far, researchers haven’t found any interactions with other medications in the clinical trials. However, all of the trials except one (Janssen) excluded people who are taking immunosuppressing or immune-modifying drugs, such as those commonly prescribed for cancer and autoimmune diseases. The trials also excluded people who are taking anticoagulant (anti-clotting) and antiplatelet medications. That means no safety or effectiveness data is available for people in those groups. When the CDC makes its recommendations, it will specify if people taking any specific medications or undergoing specific therapies should avoid vaccination.

Q: Is the vaccine safe for children? When will they be able to get it?

Vaccines must be shown in clinical trials to be safe and effective in children before the FDA will allow their use in children or the CDC will recommend them. Pfizer has begun testing in children aged 12 and older, and Moderna recently announced plans to test its vaccine in 3,000 teens. If those trials go well, they may go on to conduct trials in younger children, following a pattern typical in drug and vaccine trials in general.

“They’re first tested in adults, then older children and adolescents, and we kind of work our way down to younger and younger children,” Moss said. It’s unclear when the other companies will begin testing in children, but it will only occur after there is adequate safety data in adults. “I’m hopeful that by the school term of fall 2021, we will certainly have a vaccine we can administer to children over 12, and I think we have a good shot of having a vaccine for even younger children as well,” Moss said.

Q: How can I be sure that the process of the vaccine’s development and approval wasn’t inappropriately influenced by political interests?

After evidence surfaced of the Trump administration’s meddling at the CDC and given criticism of the administration pressuring the FDA to grant an EUA to hydroxychloroquine (which was later revoked), it’s reasonable to have concerns about political influence in the Covid vaccine development process. Fortunately, several safeguards in the vaccine approval process — even for an EUA — are reassuring.

“One of the things that I point out is that yes, there have been instances [in the history of vaccine development] where scientists have been unethical, and these safeguards are in place to really limit the ability of any one scientist in being unethical,” said Andrasik.

Two of the biggest safeguards are the VRBPAC and ACIP committees, both of which are made up of independent experts who are not employees of the FDA or the CDC and both of which hold open meetings available to the public. For example, President Trump issued an ultimatum to the FDA on Dec. 11, demanding that the agency approve the Pfizer vaccine or he would fire FDA Commissioner Stephen Hahn, a move hardly reassuring to those who want the agency to make its decisions without political pressure. However, by that point, the vaccine had already been approved by the UK’s regulatory agency and had been reviewed by VRBPAC, which found its data on safety and effectiveness strong enough to recommend the FDA issue an EUA. The FDA nearly always follows VRBPAC recommendations, and the President has no ability to influence VRBPAC’s independent members.

In addition, every vaccine trial has an independent safety monitoring board responsible for overseeing the safety of the trial. You may have heard of some vaccine trials that were paused while an adverse event was investigated. That means the process is working: If someone has a heart attack, the trial stops vaccinating new participants until the study leaders can determine if the heart attack could have been related to the vaccine. Once it’s determined that a serious medical event is not related to the vaccine, the trials resume.

Finally, look to regulatory agencies outside the U.S., Greyson said. “I think something that we in the United States lose sight of is that many, many other countries around the world are also assessing Covid-19 vaccines, and if you’re worried about whether you can trust your own country’s institutions, you can look at other countries to see if they’re also approving those vaccines,” she said. “If they are, you can have more confidence that the approval wasn’t made inappropriately or under political pressure.”

Q: Will any other authorities be looking at the safety and effectiveness of the vaccine besides the FDA and CDC?

Yes. In addition to the United Kingdom’s recent approval of the Pfizer/BioNTech vaccine — the first country to approve a well-tested Covid-19 vaccine and begin vaccinating the public — the U.K. will likely approve the AstraZeneca vaccine developed with Oxford University next. The European Medicines Agency (EMA) is reviewing the Moderna and Pfizer vaccines applications, both submitted December 1, and has begun a “rolling review” of the Janssen vaccine. Health Canada has also begun a rolling review of the Janssen vaccine and is reviewing data for three other vaccine candidates. Australia, New Zealand, India, and other countries are also reviewing data for the Pfizer vaccine, and others developed in the U.S.

Q: What happens if I do have a really serious reaction to a Covid vaccine? Will I be compensated?

Very severe reactions to a vaccine are extremely rare, but that doesn’t mean they never happen. Under the Public Readiness & Emergency Preparedness Act (PREP), the federal government has taken into account the possibility that emergency measures to address the pandemic — including vaccines used with an EUA — could potentially cause unforeseen harm. The PREP Act, therefore, includes the Countermeasures Injury Compensation Program (CICP), which may provide benefits, such as medical expenses, lost employment income, benefits to the estate or survivor death benefits, to those who experience an injury and file for the benefits.

After any Covid-19 vaccines receive full FDA approval, they will no longer fall under the CICP program, but they will fall under a very similar one called the National Vaccine Injury Compensation Program (NVICP). The NVICP provides compensation to people who experience an injury due to a vaccine. The NVICP is a no-fault system, which means if it’s biologically plausible that the vaccine caused the injury, or it’s a known injury that can occur in extremely rare circumstances from the vaccine (less than one in several million doses), the person receives compensation without having to prove the vaccine caused the injury and without the vaccine manufacturer being found at fault for a faulty vaccine. You can learn more about the differences between NVICP and CICP here.