Vaccine basics

COVID-19 Vaccines

COVID-19 Vaccines

As the COVID-19 pandemic continues to impact our lives and our community, we look forward to learning more about the COVID-19 vaccines that will soon be available.

Getting vaccinated against COVID-19 will be one of the best ways to protect yourself and others around you.

Below are the answers to frequently asked questions about COVID-19 vaccines. This information will continue to be updated as MCW receives new information from the CDC, DHS and other infectious disease experts.

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COVID-19 Vaccines What Experts Say About Safety

COVID-19 Vaccines: What Experts Say About Safety


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COVID-19 Vaccines Community Protection2

COVID-19 Vaccines: Community Protection


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COVID-19 Vaccines What to Expect

COVID-19 Vaccines: What to Expect


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COVID-19 Vaccine Journey: Leonard E. Egede, MD, MS

Leonard E. Egede, MD, MS, as a front-line healthcare provider, was among the first group of individuals to receive the COVID-19 vaccine at MCW. He will be documenting his experience through a video series.

Video, slide deck available from MCW community briefings on COVID-19 vaccines

MCW recently hosted two virtual community briefings on the COVID-19 vaccine to provide up-to-date information on vaccine safety, distribution planning, what you can expect from the vaccine and community protection. The webinars featured Dr. John Raymond and Dr. Laura Cassidy and included a Q&A for the community.

View the December 18 video

View the December 21 video

View the presentation (PDF)

What we know about the COVID-19 vaccine today

Who should get a COVID-19 vaccine?

Getting the vaccine is strongly encouraged for most individuals. The COVID-19 vaccines are being made available in phases to assure the highest benefit to the community. Phase 1A will focus primarily on frontline health care workers, residents and workers at long term care facilities and other emergency responders at high risk for infection by coronavirus. This will safeguard the healthcare system and preserve the ability to provide care for those who need it. This initial phase will expand to include other essential workers and people at very high risk for hospitalization or death from COVID-19. It is anticipated that supplies of the vaccine(s) could be sufficient to provide to the general population in the late Spring or early Summer of 2021.

Is a COVID-19 vaccine authorized for use in the U.S.?

The Pfizer vaccine was reviewed and approved for emergency use authorization (EUA) on Dec. 11, 2020, and the Moderna vaccine was approved for EUA on Dec. 18, 2020. Two additional vaccines, one from AstraZeneca and one from Johnson & Johnson, are anticipated to be reviewed for EUA in early 2021.

What does the FDA's Emergency Use Authorization mean?

When safety and quality criteria are met, Emergency Use Authorization (EUA) allows for the use of medical products in an emergency to diagnose, treat, or prevent serious or life-threatening diseases. The EUA process conducted by the FDA is extremely rigorous to ensure safety standards.

Is receiving the COVID-19 vaccine safe?
Both the Pfizer and Moderna COVID-19 vaccines have undergone extensive study and review with tens of thousands of immunizations already accomplished and all data suggest that the vaccines are not only safe but highly effective. This process involves gathering data about the effectiveness and potential effects of the vaccines that are reviewed by multiple federal agencies responsible for public health and safety. The vaccines have also been tested among a broad range of ages, races, ethnicities, and people with pre-existing comorbidities. By the time COVID-19 vaccines are distributed to general population, they will have undergone a high standard of safety and regulatory approvals based on results of research conducted on thousands of individuals. These safety approval boards include scientists and experts in infectious disease and vaccination that have no connection with the companies producing the vaccines. These individuals evaluate the safety based entirely on the data from the clinical trials. The safety standards for vaccines are even more strict than other medical interventions as these are given to potentially millions of healthy people. The speed of the COVID-19 vaccine development up to the approval stage underscores the advancement in scientific research and is based on decades of experience with production of vaccines for hundreds of other diseases. It does not indicate rushing of the regulatory checks and approval processes.
Is there any risk involved with receiving the COVID-19 vaccine?

The risk of any vaccine causing serious harm, or death, is extremely small but possible. A vaccine, like any medicine, could cause serious problem, such as a severe allergic reaction. The COVID-19 vaccines are new, and some effects may not yet be known. Historically, long-term side effects from vaccines have been rare. People with a history of severe allergic reactions (to medications or food) or anaphylaxis should consult with their health care provider prior to receiving COVID-19 vaccination.

Why is it important to consider receiving the COVID-19 vaccine?

The devastating impact of COVID-19 has resulted in hundreds of thousands of deaths in the United States, to date. These vaccines offer a safe and effective way to slow and potentially stop the toll of this public health crisis. The vaccines work with your immune system so that your body will be ready to fight the virus if you are exposed. It is important for each person to carefully weigh all available information when making the best-informed choice about receiving the vaccine.

How effective is the COVID-19 vaccine?
Pfizer and Moderna are the two companies whose vaccines are currently authorized for emergency use by the Food and Drug Administration (FDA). During their clinical trials, both vaccines were found to be more than 90 percent effective. In those who still contracted COVID-19, the vaccine was found to protect patients from developing severe infections and symptoms.
How is the COVID-19 vaccine administered? Is it a shot? Is it multiple shots?
Both the FDA-authorized Pfizer and Moderna vaccines require two shots. The first shot (initial dose) starts building resistance and the second shot (booster), administered three (Pfizer) or four (Moderna) weeks later, is needed to provide the most protection the vaccine has to offer and increase the likelihood that you will develop antibodies and build immunity. Shots are typically administered in the upper arm.
How long past the second injection date can someone receive their second dose?
We do not know the answer to this question yet. One shot gives about 50% protection. Two shots give 95% protection. The CDC recommends that the second shot be administered as close as possible to the target date: 21 days for the Pfizer vaccine and 28 days for the Moderna vaccine. Manufacturers are talking about a 1-2 week widow leeway for the second shot, but that guidance might change based on experience going forward.
What can you expect from the COVID-19 vaccine?

Reported responses to the COVID-19 vaccines are similar to other vaccines like the flu shot, and may include soreness, redness and swelling at the site of the injection; and fatigue, nausea, muscle pain, chills, joint pain and headache. These are all signs that your immune system is working. These minor symptoms develop within one to two days from the shots and last generally one day. The CDC indicates the benefits of the vaccine outweigh the risks of getting ill from COVID-19. If you experience other symptoms after receiving the vaccine, please consult your health care provider and follow their recommendations for self-isolation and care.

How long does the COVID-19 vaccine take to become fully effective in my system or for me to develop immunity?

In Phase 3 trials, the Pfizer vaccine showed a 95% efficacy rate seven days after the second dose. The vaccine was 94% effective in adults >65 years old. The Moderna vaccine showed a 94% efficacy rate 14 days after the second dose. These results were consistent across gender, age, race and ethnicity. The length of immunity following vaccination is not yet known for COVID-19. Given the novel nature of this virus and vaccine development, long-term data is not yet available to guide future vaccine protocols.

How do I know if the COVID-19 vaccine is working?

Unfortunately, you won't be able to tell if you are protected. Even after getting vaccinated you need to continue to limit trips outside of your home, practice physical distancing and wearing face coverings.

Will there be any sort of certificate or record we can use to prove we have had the vaccine?
You will receive a CDC vaccination card at the time of your vaccination that will indicate the manufacturer and the lot # of your first dose. We also report all COVID-19 vaccine administrations to the Wisconsin Immunization Registry. You need to return to the same location (within the specified time period) that you received the first dose to ensure you are receiving the correct second dose.
Is there a list of potentially allergy-inducing ingredients that people can check before getting a vaccine to avoid a serious reaction?
For a full list of ingredients in the Pfizer COVID-19 Vaccine, view the Pfizer Fact Sheet for Recipients and Caregivers. For a full list of ingredients in the Moderna COVID-19 vaccine, view the Moderna Fact Sheet for Recipients and Caregivers.
If I receive the vaccine, does that mean I won't get COVID-19?

The results of the clinical data available are encouraging. They indicate that these vaccines provide a very high level of protection against COVID-19 or, at the very least, make it so that a person who becomes infected has a milder course of disease without as many complications. Widespread vaccination for COVID-19 means that the virus cannot infect as many people, which results in fewer people spreading the virus throughout our communities. This is referred to as “community protection."

Do I still need to get tested if I have received the vaccine but then am exposed to someone with COVID-19?
Given the limited information currently available on how much the mRNA COVID-19 vaccines may reduce transmission in the general population and how long protection lasts, vaccinated persons should continue to follow all current guidance to protect themselves and others. This includes following quarantine guidance after an exposure to someone with COVID-19.
How long is the COVID-19 vaccine effective?

We don’t know yet, but immunity is expected to be strong for months. Researchers will not know how long immunity lasts until they are able to follow people who receive the vaccine over longer periods of time. This will also help determine whether further booster doses are required.

Will those who are vaccinated test positive for COVID-19 following vaccination?

You should not test positive for COVID-19 due to being vaccinated but will test positive for the antibodies that fight the virus.

Should I still get the vaccine if I was COVID-19 positive in the past?

Yes. According to the CDC website, there is not enough information currently available to say if or for how long after infection someone is protected from getting COVID-19 again; this is called natural immunity. Early evidence suggests natural immunity from COVID-19 may not last very long, but more studies are needed to better understand this.

How long after having COVID-19 should people wait before being vaccinated?
You may receive the Pfizer and Moderna COVID-19 vaccines if you have already had COVID-19 infection, are not acutely ill and have met the CDC criteria for discontinuing isolation: At least 10 days have passed since symptom onset AND at least 24 hours have passed since resolution of the fever without use of fever-reducing medications AND other symptoms have improved. If you have had prior COVID-19 infection, you may delay vaccination for 90 days after the infection, since reinfection is not common during this time frame.
Is this a live virus vaccine? Could it make others I come in contact with sick?

No, the COVID-19 vaccines are mRNA vaccines and do not contain virus or virus particles. Thus, it is impossible to get COVID-19 from the vaccine. You will not be contagious or shed live virus.

Are there people who shouldn't get it? (age, immunocompromised, etc.)

The COVID-19 vaccine has not yet been approved for children under the age of 16. People who are pregnant or breastfeeding or those with severe allergies to vaccines should consult their health care provider before taking the vaccine.

Can those who are pregnant or trying to become pregnant get the COVID-19 vaccine?

Those who are pregnant or those trying to become pregnant and those who are breastfeeding were not included in vaccine trials and the risk to the baby is unknown. Discussing the risks and benefits of the vaccine should be considered with your health care provider.

If I have a cold or mild fever, should I get vaccine?
If an individual gets vaccinated when they have a cold or mild fever, the vaccine will still be safe and effective. However, during this pandemic, it is important that an individual with a cold or mild fever strongly consider being tested for COVID-19 and stay home until they receive negative results and their symptoms go away. A reason for not vaccinating someone with a cold or mild fever is because that person may have COVID-19 and spread it to people they come in contact with during the vaccination process. In addition, assessing symptoms following the vaccine when already having symptoms from a cold could be confusing.
Does the COVID-19 vaccine interact with other medications you are on?
Approved vaccines should not interact with other medications, but if you have concerns, discuss your medications and the vaccine with your primary care doctor.
How are the COVID-19 vaccines that have been developed different from one another?

All of the COVID-19 vaccines are designed to teach your immune system how to fight off the virus. Their differences include their doses; that they are not interchangeable (if you receive the Pfizer vaccine for your first dose, you must receive the Pfizer vaccine for your second dose); and that they require different storage. For example, the Pfizer vaccine needs to be kept in ultra-cold storage.

Learn more on the COVID-19 Vaccine Tracker

Where can I learn more specifically about the Pfizer COVID-19 vaccine?

The FDA has created an Emergency Use Authorization (EUA) Pfizer-BioNTech COVID-19 Vaccine Fact Sheet that contains information to help the public understand the risks and benefits of this specific vaccine.

Learn more

Do individuals need to quarantine after being vaccinated?

No. The COVID-19 vaccines do not contain virus or virus particles. Thus, it is impossible to get COVID-19 from the vaccine. You will not be contagious or shed live virus. Individuals should monitor for symptoms and follow appropriate guidance from their primary care provider.

Will I have to get the COVID-19 vaccine every year?

At this time, we are anticipating that this vaccine will be given only using two shots (21 or 28 days from each other), but future booster shots might be needed.

When will a vaccine for children under the age of 16 be coming out?
It is going to take time, perhaps even months, before those younger than 16 can get a COVID-19 vaccine, as trials to test the vaccine candidates’ immunogenicity are either underway or have yet to begin. Pfizer- BioNTech announced in October they were expanding testing of their vaccine to those 12 and older. A similar announcement is expected soon from Moderna, which has partnered with the National Institutes of Health on an experimental vaccine. It is unlikely that children will be able to receive the vaccine before summer.
Does the COVID-19 vaccine stop the transmission of the virus?

We know that the COVID-19 vaccines protect a person from getting moderately to severely ill with COVID-19. A small number of people may get COVID-19 infection with mild symptoms. However, we don’t know yet if the vaccine produces what is called sterile immunity (not referring to human reproduction) that prevents those who have been vaccinated from infecting others or if people who have received the vaccine can still spread the virus through asymptomatic (not experiencing symptoms) transmission.

Since we don’t know if taking the vaccine will help prevent COVID-19, then what’s the benefit to taking the COVID-19 vaccine?

You will be protected from severe forms of COVID-19, with less chance of dying from the virus. There is not enough information currently available to say if or for how long after infection someone is protected from COVID-19 infection. Early evidence suggests natural immunity from COVID-19 may not last very long, but more studies are needed to better understand this. We know COVID-19 has caused very serious illness and death for many people. If you get COVID-19, you also risk giving it to loved ones who may get very sick. Getting a COVID-19 vaccine is a safer choice.

How would a virus mutation effect the efficacy of the current vaccine?
The vaccine developers are carefully monitoring any virus mutations to make sure the current vaccines are still effective, and, if needed, they will swiftly adjust the vaccine just like they do for the seasonal flu.
How many people will need to be vaccinated against COVID-19 to achieve herd/community immunity resulting in community protection?

Herd immunity (or community immunity) is a term to describe the situation when most individuals have protection from the virus so that there are not enough susceptible people remaining in a community for the virus to spread. As a result, everyone within the community is protected, even if a small number of people do not have any protection themselves. The percentage of people who need to have protection in order to achieve herd immunity varies by disease. At this time, experts estimate that at least 75% of people within a community will need to have developed immunity to begin controlling the COVID-19 pandemic.

Can I get the COVID-19 vaccine if I got a flu shot this year?

Yes, people who got a flu shot can and should receive the vaccine when it becomes available. We encourage you to get your flu shot, if you have not already done so. A flu shot provides many benefits, including keeping you from getting sick with the flu and reducing the severity of your illness if you do get the flu.

How can I learn more?

Carefully review all materials provided to you when you are notified that you are eligible to receive the COVID-19 vaccine BEFORE you schedule your vaccination. You can also visit the following online resources:

What we know about COVID-19 vaccine distribution – general

Who is responsible for prioritizing who will be offered the COVID-19 vaccine first?
The Centers for Disease Control and Prevention (CDC) and the Wisconsin Department of Health Services (DHS) have issued guidance on prioritization, with health care workers and nursing home residents (long-term care residents) being among the first to receive the vaccines, followed by police and fire personnel. Those over 65 will also be eligible on January 25. Additional groups will be identified and prioritized as additional doses of the vaccines become available.
When will the COVID-19 vaccine be offered to patients and/or the general public?

The CDC’s guidelines for prioritizing the first shipment of vaccines does not include the general population. The vaccine distribution is staged by the CDC and the Wisconsin Department of Health Services (DHS) and will be available in phases and these phases may overlap:

  • Phase 1a: Health care workers and nursing home residents (long-term care residents) who may directly or indirectly be exposed to COVID-19.
  • Phase 1b: Police and fire personnel and adults ages 65 and over; future priority populations as yet to be finalized.
  • Phases 2 and 3: Anyone who did not receive the vaccine in phases 1a or 1b, other critical populations, general public

Vaccine availability is a fast-evolving and complex situation. Although we do not know when each of these phases of distribution will occur, we expect that the vaccines will be widely available to the public several months into 2021.

For more information on the planning and distribution process identified by DHS, view the COVID-19 vaccination plan (PDF) DHS submitted to the CDC. The latest information on phase plans and vaccines allocated and administered in Wisconsin can be found on the DHS website.

Will elderly who live at home receive the vaccine at the same time as those in senior communities?
These details are still being worked out. You may be contacted by your health provider, local health department or be asked to voluntarily register to receive the vaccine.
In the phases of distribution identified by the CDC, how are frontline personnel determined?
Frontline personnel are still being defined at the national level. Additional clarification of what roles make up frontline personnel will most likely be made at the state and local level.
Will employers with frontline personnel be notified about opportunities for those workers to get the vaccine?
These details are still being worked out. You may be contacted by your health provider, local health department or be asked to voluntarily register to receive the vaccine.
How can healthcare workers not associated with a major medical group get access to the vaccine?
Healthcare workers not associated with a major medical group should contact their local health department.
Will minority groups be given vaccine priority considering their documented susceptibility to COVID-19?
The CDC offers a Social Vulnerability Index which looks at socioeconomic status, minority population, housing, transportation, and other factors. There have been debates on whether or not to use the index in weighing vaccine distribution, particularly in early phases. It is likely that it will vary from health department to health department.
Are prisoners considered an at-risk population? Does that mean that people in prisons will receive the vaccine before the general population?
The COVID-19 vaccine distribution must prioritize vulnerable populations, and in some cases, that means incarcerated populations. Each state is handling inoculation of prisoners differently, but there may be some prioritization of prison populations as high-risk people.
How will individuals be notified that they are eligible to get the vaccine?
These details are still being worked out. You may be contacted by your health provider, local health department or be asked to voluntarily register to receive the vaccine.
Is there a way to be put on a waiting list to receive the vaccine?
These details are still being worked out.
Where will the general public go to receive their vaccine?
Vaccines will most likely be available at vaccine sites, through your doctor or local pharmacies.
Is there someone I can call to find out when it is my turn to get vaccinated?
You should contact your local health department.
With the pace of the vaccine rollout, is it reasonable to expect that bigger events like weddings could resume in fall 2021?
Mass gatherings will be safer when at least 70% of the population is vaccinated and the local positivity rates are below 5%.
Will there be enough COVID-19 vaccines for everyone?

There may be a limited supply of COVID-19 vaccines before the end of 2020, but supply is expected to increase gradually throughout the first half of 2021. The goal is for everyone to be able to easily get a COVID-19 vaccine as soon as quantities become available.

When vaccines are given out, is an equal number of doses held in reserve so those people can get their second dose? Or will that come from a separate shipment?
The second dose will come in a subsequent shipment so that we can continue to immunize as many people as possible as quickly as possible.
Will a second dose be available after I receive my first dose?
Yes. You will receive your second dose at the appropriate time at the same location you received your first dose.
When multiple types of the COVID-19 vaccine are available, will I have a choice of which one I get?

Because of limited supply and significant distribution needs across the country, it is unlikely individuals will be given a choice of COVID-19 vaccine.

What is the cost of the COVID-19 vaccine?

At this time, we expect that there will be no cost to individuals to receive the vaccine. However, we are awaiting more details.

What can we do to build trust among community members of color so they are more comfortable getting the vaccine?
It is critical that we work together to build trust in communities of color around the COVID-19 vaccine. Distrust of the healthcare system is, in part, due to a history of racism and lived experiences. People have lots of questions and deserve to have them answered. In order for communities of color to be receptive to messages about vaccine safety, one important avenue is to share them through popular opinion leaders within their community.

Vaccine Basics

Through vaccination, people can develop immunity without suffering from the actual diseases that vaccines prevent. Learn the basics of vaccines and why they are so important to the health of our community.

Key Terms

Antibody: A protein found in the blood that is produced in response to foreign substances (e.g. bacteria or viruses) invading the body. Antibodies protect the body from disease by binding to these organisms and destroying them.

Bacteria: Single-celled organisms that live in and around us with a distinct structure from other microbes. Bacteria can be helpful, but can also cause illnesses such as strep throat, ear infections, and pneumonia.

Germs: Living organisms, like bacteria, fungi, or viruses, which can cause infections or disease.

Herd Immunity: When a large percentage of the population becomes immune to a disease through vaccination and/ or recovery from infection. If enough people are immune, it limits spread and protects the entire community.

Immunity: Protection from an infectious disease. If you are immune to a disease, you can be exposed to it without becoming infected.

Immunization: A process by which a person becomes protected against a disease through vaccination. This term is often used interchangeably with vaccination or inoculation.

Outbreak: More cases of a disease at a specific time or place than expected. If the disease is new, rare, or has serious public health implications, an outbreak may be declared with as few as one or two cases.

Vaccination: The act of introducing a vaccine into the body to produce immunity to a specific disease.

Vaccine: A product that stimulates a person’s immune system to produce immunity to a specific disease, protecting the person from that disease. Vaccines are usually administered through needle injections but can also be administered by mouth or sprayed into the nose.

Virus: A tiny organism that multiplies within cells and causes disease such as chickenpox, measles, mumps, rubella, pertussis and hepatitis. Viruses are not affected by antibiotics, the drugs used to kill bacteria.

Frequently Asked Questions

How do vaccines prevent disease?

Vaccines contain the virus or bacteria (or parts of virus or bacteria) that cause disease. For example, measles vaccine contains measles virus. The virus in the measles vaccine is weakened to the point that it doesn’t cause disease. Some vaccines have a killed version of the germ, such as the vaccine against Hepatitis A. Others have only a piece of the germ, such as with the meningococcal vaccine. All of these vaccines are strong enough to make the immune system produce antibodies that lead to immunity. In other words, a vaccine is a safer substitute for a person’s first exposure to a disease. The person gets protection without having to get sick. Through vaccination, people can develop immunity without suffering from the actual diseases that vaccines prevent.

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Why immunize?

Thanks to vaccines, some diseases are almost gone from the U.S. But experts still recommend that we immunize our children, ourselves as adults, and the elderly. It’s true, some diseases (like polio and diphtheria) are becoming very rare in the U.S. Of course, they are becoming rare largely because we have been vaccinating against them.

It’s much like bailing out a boat with a slow leak. When we started bailing, the boat was filled with water. But we have been bailing fast and hard, and now it is almost dry. We could say, “Good. The boat is dry now, so we can throw away the bucket and relax.” But the leak hasn’t stopped. Before long we’d notice a little water seeping in, and soon it might be back up to the same level as when we started.

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Why must we continue to immunize?

Unless we can “stop the leak” (eliminate the disease), it is important to keep immunizing. Even if there are only a few cases of disease today, if we take away the protection given by vaccination, more and more people will become infected and will spread disease to others. Soon we will undo the progress we have made over the years.

We don’t vaccinate just to protect our children. We also vaccinate to protect our grandchildren and their grandchildren. With one disease, smallpox, we “stopped the leak” in the boat by eradicating the disease. Our children don’t have to get smallpox shots anymore because the disease no longer exists. Smallpox is now only a memory, and if we keep vaccinating against other diseases, the same will someday be true for them too. Vaccinations are one of the best ways to put an end to the serious effects of certain diseases.

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What if we stop immunizing?

Diseases that are almost unknown would stage a comeback. Before long we would see epidemics of diseases that are nearly under control today. More children would get sick and more would die.

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How do we know vaccines are safe?

The United States has the safest, most effective vaccine supply in its history. The nation’s longstanding vaccine safety system ensures that vaccines are as safe as possible. As new information and science become available, the system is updated and improved.

As part of these vaccine safety efforts, scientists ensure the safety of vaccines by conducting different types of studies:

  • Clinical trials are done before a vaccine is made available. Vaccine manufacturers conduct these studies as part of the development, testing, and approval process. The Food and Drug Administration (FDA) uses the information from clinical trials to decide if a vaccine is safe, effective, and ready to be licensed for use.
  • Post-licensure safety studies are conducted after a vaccine is approved and in use. These studies are part of continuous vaccine safety monitoring and often look at populations that might be underrepresented in clinical trials. Importantly, these studies can look for rare adverse events.

The United States’ long-standing vaccine safety program closely and constantly monitors the safety of vaccines.

A critical part of the program, CDC’s Immunization Safety Office identifies possible vaccine side effects and conducts studies to determine whether health problems are caused by vaccines.

Data show that the current U.S. vaccine supply is the safest in history.

What are the differences between active and passive immunity?

Immunity to a disease is achieved through the presence of antibodies to that disease in a person’s system. Antibodies are proteins produced by the body to neutralize or destroy toxins or disease-causing organisms. Antibodies are disease-specific. For example, measles antibody will protect a person who is exposed to measles but will have no effect if he or she is exposed to mumps.

Active immunity results when exposure to a disease organism triggers the immune system to produce antibodies to that disease. Exposure to the disease organism can occur through infection with the actual disease (resulting in natural immunity), or introduction of a killed or weakened form of the disease organism through vaccination (vaccine-induced immunity). Either way, if an immune person comes into contact with that disease in the future, their immune system will recognize it and immediately produce the antibodies needed to fight it.

Active immunity is long-lasting, and sometimes lifelong.

Passive immunity is provided when a person is given antibodies to a disease rather than producing them through his or her own immune system.

A newborn baby acquires passive immunity from its mother with antibodies that cross the placenta. A person can also get passive immunity through antibody-containing blood products such as immune globulin, which may be given when immediate protection from a specific disease is needed. This is the major advantage to passive immunity; protection is immediate, whereas active immunity takes time (usually several weeks) to develop.

However, passive immunity lasts only for a few weeks or months. Only active immunity is long-lasting.

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