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COVID-19 Vaccines

Information resources about the COVID-19 Vaccinations


See all of the frequently asked questions from the University of Chicago Medical Center COVID-19 Vaccine Information.

FAQ below updated as of 01/11/2021. Please see link above for most updated information.

What is the COVID-19 Vaccine?

The COVID-19 vaccine is an immunization to protect people from SARS-CoV-2, the virus that causes COVID-19.

Vaccination is a safe and effective way of protecting people against harmful and infectious diseases. Vaccines stimulate your body’s natural defenses to build resistance and make your immune system stronger. They cannot cause the disease or put you at risk of its complications. Most vaccines are given by an injection, and some are given orally (by mouth) or sprayed into the nose. COVID-19 vaccines in development are given by injection.

Why get vaccinated?

It is important to get vaccinated because we aren’t just protecting ourselves, but also those around us. Some people, including those who are seriously ill, are advised not to get certain vaccines and depend on the rest of us to get vaccinated to help protect them and reduce the spread of disease.

Vaccines reduce the risk of getting a disease by working with your body’s natural defenses to build protection. When you get a vaccine, your immune system typically responds by:

  •  Recognizing the invading germ, such as a virus or bacteria.
  •  Producing antibodies. Antibodies are proteins produced naturally by the immune system to fight disease.
  •  Remembering the disease and how to fight it. If you are exposed to the germ in the future, your immune system can destroy it before you become unwell.

When a person gets vaccinated against a disease, their risk of infection is also reduced. That means they’re far less likely to transmit the disease to others. As more people in a community get vaccinated, fewer people remain vulnerable to infection, which means there’s less possibility of people passing the pathogen from one person to another. Lowering the possibility for a pathogen to circulate in a community protects those who cannot be vaccinated due to other serious health conditions from the disease targeted by the vaccine. This is called “herd immunity.”

How was the vaccine developed so quickly?
Typically, it takes years to develop vaccines, assure their safety and efficacy, and then manufacture them on a mass scale. Because of the seriousness of the COVID-19 pandemic, the timeline was accelerated through national and international programs supporting the work of scientists around the globe, including teams here at UChicago Medicine. The research and development process was accelerated to allow scientists to perform many steps simultaneously rather than sequentially. The federal effort also provided funding to support the work of pharmaceutical companies to begin manufacturing vaccines before they are approved — allowing for quick distribution if and when the vaccines earn an FDA authorization.

Can you provide additional detail about the vaccine development process?

Here’s a summary of the development process:

  • After preliminary research in a lab, scientists tested the vaccines during clinical trials designed to make sure each immunization met or exceeded established safety and efficacy thresholds.
    • Trials began with small groups of people before expanding to include much larger numbers, making sure to include a wide range of people from across the country and around the world. This includes people of different ages, races, sexes, and health conditions. Scientists studied how well the vaccines worked when compared to a control group, which received a placebo version of the vaccine.
    • If clinical trial participants reported certain serious “adverse events” the trial may be placed on hold until the event(s) is investigated.
      •  The trials are only restarted once scientists are confident it is safe to continue.
    • Pharmaceutical companies also tracked clinical trial participants after they received a vaccine to make sure they remained healthy and will continue to do so for up to two years.
  •  All of the research data collected in the vaccine’s development is being reviewed by an independent advisory committee (Vaccine and Related Biological Products Advisory Committee) before the full FDA decides whether to issue an EUA.

For additional detail, visit the FDA’s website.

How effective is the COVID-19 vaccine?
Vaccines developed by Pfizer/BioNTech and Moderna have had an independent interim analysis performed on their vaccines. The Pfizer/BioNTech vaccine was reported to be 95% effective after two doses, and 52% effective after the first dose alone. The Moderna vaccine was reported to be 94.5% effective. In documents released December 8, the FDA evaluated data provided by Pfizer/BioNTech and determined that the vaccine is highly effective with even a single dose, with coronavirus cases quickly flatlining about 14 days after the first dose of the vaccine. This is true for all group of participants who were evaluated, regardless of age, weight, or race. In documents released on December 17, the FDA evaluated data provided by Moderna and agreed with their report that the vaccine is 94% effective at preventing COVID-19 in all groups of participants regardless of age, weight, or race after two doses given 28 days apart.

Is the vaccine safe?
Only vaccines that meet standards for safety and effectiveness (known as efficacy) are approved for emergency use by the FDA. Vaccines are assessed to see whether and how well they can protect people from SARS-CoV-2, the virus that causes COVID-19. Any approved COVID-19 vaccine is tested in a trial of at least 30,000 volunteers and reviewed to make sure it is safe. Like any medical therapy, getting vaccinated is accompanied by some degree of risk. However, the reported potential risks and side effects of a COVID-19 vaccine are substantially lower than the risks and side effects associated with contracting SARS-CoV-2. When evaluating the data provided by Pfizer/BioNTech, the FDA concluded that there are no meaningful imbalances in adverse events between the placebo group and the vaccine group, meaning that there was no statistically significant increase in the risk of experiencing a serious health complication when receiving the vaccine. The FDA’s analysis of data provided by Modern has indicated there are “no specific safety concerns that would preclude issuance of an EUA”.

What are the vaccine’s side effects?

All medical treatments have some degree of risk. For vaccines, that risk is typically small. Many vaccines have mild side effects, which usually range from soreness at the site of injection to a slight fever, body aches and a headache. You can read more here. Clinical trials for the COVID-19 vaccine have shown they are 94-95% effective.

  • Pfizer: Side effects including injection site pain, fever, chills, fatigue, muscle pain, joint pain, headache and swollen lymph nodes. Data from Pfizer’s clinical trial, published December 10, showed that the most common side effect was injection site pain. That was followed by fatigue and headache that was primarily mild to moderate. Only 0.5% of those in the vaccine trial reported a severe reaction of which 3.8% had severe fatigue and 2% had severe headache. Fever was infrequently reported (3.7%). Side effects were more commonly seen in people between the ages of 18-55 than those who were 65-85. They were also slightly more likely to occur after the second dose. Side effects typically peaked within two days and were completely over within seven days.
  • Moderna: Early data from Moderna’s clinical trial also showed typical mild-to-moderate side effects, such as headaches, fatigue, muscle aches, chills, and injection site pain. The independent board that conducted the interim analysis of Moderna’s large-scale trial found severe side effects included fatigue in 9.7% of participants, muscle pain in 8.9%, joint pain in 5.2%, and headache in 4.5%. Reactions typically occurred within 1-2 days of receiving the vaccine and tended to go away quickly. They were all resolved within seven days.

Different people can react differently to receiving a vaccine and some people have no reactions at all. However, it’s important to know that risks reported in connection with the COVID-19 vaccine are significantly lower — and markedly less severe — than the risks associated with contracting COVID-19 itself.

Are there concerns about any long-term side effects?
Given the new nature of the COVID-19 vaccine, there hasn’t been an opportunity to gather data on the vaccines’ long-term side effects. With the Pfizer/BioNTech vaccine, the FDA determined that there is no increased risk of adverse events within the first two months following vaccination. The clinical trials will continue after EUA is issued to collect long-term safety data on these vaccines. The FDA’s analysis of the Moderna vaccine determined rates of serious side effects were similar in both the placebo and vaccine groups of the trial. The most noteworthy issue seen was Bell’s Palsy, a temporary paralysis of muscles in the face; however, the rate at which it occurred in the vaccine and placebo groups was not greater than the rate of incidence in the general population and therefore there is no evidence that these cases were linked to the vaccine. Some people who had had lip filler injections also experienced lip swelling after the vaccine.

Can I get COVID-19 from the vaccine?
No. Much like you don’t get influenza from a flu shot, it is not possible to get COVID-19 from a COVID-19 vaccine. You may feel unwell after getting vaccinated, and you will not have full protection from the virus until at least 14 days have passed from your second dose. Given our region’s widespread community transmission, that means you could still catch COVID-19 after being immunized and before your body’s immune system has reached its full ability to fight the virus. In addition, much like the flu vaccine, COVID-19 vaccines are not 100% effective, which means there is a chance you could contract COVID-19. However, researchers believe you may be less likely to get as sick as you would if you were unvaccinated.

Do I need to take any specific precautions after getting the vaccine, particularly if I’m going back to work or plan to spend time around others?
Your vaccination poses no risk to others, so you can continue to interact safely with colleagues, patients, and family members. You may develop side effects such as site pain, fever, chills, fatigue, muscle pain, joint pain, headache and swollen lymph nodes. These typically last for 24-48 hours. Most of these reactions will be mild to moderate and are a sign that your immune system is activating to protect you from the virus.
Some people may have no side effects. However, others people may have severe, short-lived reactions. You may continue to work after getting your second dose even if you have mild side effects. If you do not feel well enough to work after your vaccine, please use your sick leave. You will need to stay home from work if you have any of the following symptoms and you may need to get a COVID-19 test:

  •  Cough
  •  Fever of more than 100.0F
  •  Loss of taste and smell
  •  Runny or stuffy nose
  •  Shortness of breath
  • Side effects that get worse after two days or 48 hours
  • Sore throat

Will I need to wear a mask and follow other restrictions after I get vaccinated?
Yes. It will take months for the full roll out of the vaccine. It is also not yet clear whether or not people who have been vaccinated can still act as carriers for the virus. People will need to wear masks, practice social distancing, wash their hands, and take other precautions until we’ve reached herd immunity. That occurs when a large portion of the population is vaccinated, making it difficult for infectious diseases to spread, because there are not many people who can be infected. Herd immunity works only if most people are vaccinated.

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