COVID-19 Vaccine

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Hundreds of millions of Americans have received COVID-19 vaccines since December 2020.

The vaccines — developed by Pfizer-BioNTech, Moderna, Novavax, and Johnson & Johnson/Janssen (J&J) — are safe and effective in preventing COVID-19. They are especially effective in protecting against severe illness, hospitalization, and death.

However, scientists are still learning about the vaccines’ effects on certain groups of people. One such group is the immunocompromised, people who have weakened immune systems because of health conditions or treatments.

Immunocompromised people are at higher risk for complications from COVID-19, which makes the vaccine crucial.

UPMC is conducting the COVID-19 Vaccine in the Immunocompromised Study (CoVICS) to learn more about the vaccines’ ability to protect immunocompromised people.

COVID-19 and Immunocompromised People

People who are immunocompromised have a weakened immune system. Medical conditions — AIDS, cancer, diabetes, malnutrition, and more — can cause a compromised immune system. So can certain medicines and medical therapies that suppress the immune system.

Because the immune system is crucial in fighting off disease, immunocompromised people may be vulnerable to certain infections, including COVID-19.

According to the Centers for Disease Control and Prevention (CDC), immunocompromised people are at higher risk for complications from COVID-19. They are more likely to have severe illness, be hospitalized, or die.

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Is the COVID-19 Vaccine Safe for Immunocompromised People?

The COVID-19 vaccines developed by Pfizer, Moderna, and J&J do not contain a live virus. Because of that, immunocompromised people can get these vaccines.

For safety reasons, immunocompromised people can’t get some vaccines — such as ones that contain a live but weakened virus or bacteria (like the measles/mumps/rubella vaccine).

The CDC says there is no data that shows the vaccines are unsafe for people who are immunocompromised.

Is the COVID-19 Vaccine Effective in Immunocompromised People?

There is no fully reported data on the efficacy of the COVID-19 vaccine in immunocompromised patients. Scientists are monitoring the vaccines’ efficacy as distribution continues.

People who have a weakened immune system may not have a full immune response to the vaccine.

A University of Pittsburgh/UPMC study published in the journal medRxiv in April 2021 reported many patients with cancers affecting the blood, bone marrow, or lymph nodes didn’t have an immune response to the COVID-19 vaccine.

According to the study, 46% of the participants did not produce antibodies. Patients with B cell chronic lymphocytic leukemia were especially at risk.

“As we see more national guidance allowing for unmasked gatherings among vaccinated people, clinicians should counsel their immunocompromised patients about the possibility that COVID-19 vaccines may not fully protect them against SARS-CoV-2,” says Ghady Haidar, MD, a UPMC transplant infectious diseases doctor and the study’s senior author. “Our results show that the odds of the vaccine producing an antibody response in people with hematologic malignancies are the equivalent of a coin flip.”

UPMC’s COVID-19 Vaccine in the Immunocompromised Study (CoVICS) is measuring the vaccine’s effectiveness in immunocompromised people.

In June 2021, UPMC reported early results from the study. The data showed immunocompromised patients had a wide range of antibodies to the COVID-19 vaccine, depending on their condition.

According to the study:

  • 37.2% of vaccinated solid organ transplant patients made antibodies after vaccination.
  • 54.7% of blood cancer patients made antibodies.
  • 82.4% of solid tumor cancer patients made antibodies.
  • 83.8% of patients with autoimmune disorders made antibodies.
  • 94.6% of patients with HIV made antibodies.

Other factors, such as the type of solid organ transplant received, also had an impact on the study results. For example, only 22.2% of lung transplant patients made antibodies, compared to 60.6% of liver transplant patients. Also, patients who received their transplant less than a year ago were less likely to respond to vaccination than those transplanted earlier.

“This is important because we’ve seen several studies indicating that immunocompromised people are less likely to produce antibodies in response to COVID-19 vaccination,” says John Mellors, MD, chief, Division of Infectious Diseases, UPMC. “And we can assume this means they’re less likely to be able to fight the virus, but until we were able to test for virus neutralization, that was only an assumption.

“Our results give us more confidence in saying that people who do not produce antibodies truly are at greater risk of COVID-19 infection and that the level of antibodies produced is a proxy for ability to neutralize the virus.”

Scientists continue to monitor the safety and efficacy of the COVID-19 vaccine in immunocompromised people. Clinical studies are ongoing.

Should Immunocompromised People Get the COVID-19 Vaccine?

Because of the risk of COVID-19 for immunocompromised people, they should get the COVID-19 vaccine.

The CDC says immunocompromised people should be aware that they may have a lesser immune response to the vaccine. Because of that, they should continue to follow COVID-19 prevention methods even after getting vaccinated. This includes avoiding crowds, washing their hands, maintaining social distancing, and wearing a mask when around people not from their household.

If you are scheduled to begin immunosuppressive therapy, talk to your doctor about when to schedule your COVID-19 vaccine.

The FDA and CDC have authorized additional doses of the COVID-19 vaccine for many immunocompromised people who have completed their primary vaccine series. For more information on who’s eligible, visit the CDC website.

UPMC is currently offering additional doses of the COVID-19 vaccine to immunocompromised patients.  For more information, visit or call 844-876-2822 between 8 a.m. and 5 p.m., Monday through Friday.

COVID-19 Vaccine in the Immunocompromised Study (CoVICS)

UPMC is conducting the COVID-19 Vaccine in the Immunocompromised Study (CoVICS) to measure how well the vaccine works in immunocompromised people.

Who is eligible for CoVICS?

The study is open to immunocompromised people age 18 and older who have received or plan to receive the COVID-19 vaccine. Immunocompromised conditions include:

  • Organ transplants.
  • Blood cancers.
  • Other cancer or any form of therapy over the past 12 months.
  • HIV.
  • Autoimmune, chronic inflammatory conditions, or other conditions that required some form of therapy over the past 12 months.
  • Congenital immunodeficiencies.

If you are not immunocompromised or if you have been previously infected with COVID-19, you are not eligible for the study.

How will CoVICS work?

The study will measure the effect of the COVID-19 vaccine in immunocompromised people for up to a year. It is free and voluntary for participants.

We will draw blood from you up to five times over the course of 12 months, taking less than a tablespoon of blood each time. The blood draws can take place at several different UPMC hospital labs.

If you have already received the COVID-19 vaccine, we can schedule your first blood draw at least one week after your final dose. If you have not received the vaccine, we may schedule your first blood draw before your first dose and then another blood draw after you have finished your vaccinations.

We will check your blood for antibodies against COVID-19. As a part of your medical record, you can review these results in MyUPMC.

We may contact you to schedule more blood draws over the course of the year to see how your antibodies change over time. This data will not be part of your medical record.

The study is one of the first to verify that the ability of blood from immunocompromised participants to neutralize the virus closely mirrors their antibody levels measured by a Food and Drug Administration (FDA)-approved test, meaning that antibody testing is a good proxy for neutralizing titers.

What do the test results mean?

The antibody test may or may not predict how well the vaccine protected an immunocompromised person from COVID-19. A negative test may not mean the vaccine didn’t work. A positive test may not mean you have full protection.

No matter what the result, you should continue to follow preventive methods to lower your risk of COVID-19 infection. This includes wearing a mask in public and physical distancing. Your loved ones also can help protect you by getting vaccinated and following preventive actions like masking and physical distancing.

For more information on CoVICS or to find out if you are eligible:

Or fill out our online form.

Editor's Note: This article was originally published on , and was last reviewed on .

Mounzer Agha, MD, Maggie Blake, RN, Charles Chilleo, Alan Wells, MD, and Ghady Haidar, MD, medRxiv, Suboptimal Response to COVID-19 mRNA Vaccines in Hematologic Malignancies Patients. Link

Centers for Disease Control and Prevention, COVID-19, Extra Precautions, People With Certain Medical Conditions. Link

Centers for Disease Control and Prevention, COVID-19, Interim Clinical Considerations for Use of COVID-19 Vaccines Currently Authorized in the United States. Link

Centers for Disease Control and Prevention, COVID-19, Vaccine Considerations for People with Underlying Medical Conditions. Link

National Cancer Institute, Definition of Immunocompromised. Link

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