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Published on August 17, 2021
Third Dose of COVID-19 Vaccine Recommended for Some Patients
People who are immunocompromised may be at an increased risk of severe COVID-19 and may also be less likely than others to respond to vaccination and more likely to transmit the virus to others in their households. This group includes some people with cancer, particularly those with certain blood cancers. In response to these concerns, on Aug. 13 the Centers for Disease Control and Prevention (CDC) recommended that certain immunocompromised people received a third dose of the Pfizer or Moderna COVID-19 vaccines. The CDC’s recommendations followed an Aug. 12 decision by the U.S. Food and Drug Administration (FDA) to expand the emergency use authorization for these two mRNA vaccines to allow additional doses to be given to some immunocompromised people.
The CDC recommendations also came after an Aug. 13 meeting of the CDC’s Advisory Committee on Immunizations Practices (ACIP), which votes on evidence-based recommendations on vaccine use. The committee voted unanimously to recommended third doses of mRNA vaccines for some immunocompromised people. The recommendation applies to individuals who are moderately or severely immunocompromised, including people who have been receiving active treatment for solid or blood cancers. Solid organ transplant recipients and recent stem cell transplant patients are also considered moderately to severely immunocompromised, as are people who have certain other noncancerous conditions or are taking specific drugs. The CDC recommends that immunocompromised individuals talk to their health care providers about whether they could benefit from a third vaccine dose. Immunocompromised people getting additional doses will not be asked to prove their conditions but rather will be asked to attest that they qualify for the extra shots.
The new recommendations state that additional doses should be given 28 days or more after the second vaccine dose and that people should receive the same vaccine they were originally given. For instance, someone who had received two doses of the Moderna vaccine should receive a third dose of the Moderna vaccine. While some patients are currently getting antibody testing to determine whether they have mounted an immune response to the vaccine, antibody testing is not recommended for determining who should get extra doses.
The emergency use authorization expansion is only for the Moderna and Pfizer vaccines, meaning that people who got a Johnson and Johnson vaccine are not currently eligible to get an additional vaccine dose. Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, spoke briefly at the ACIP meeting, indicating that a route to additional doses should be available soon to immunocompromised people who received the Johnson and Johnson vaccine. “We think that at least there’s a solution here for the very large majority of immunocompromised individuals,” he said, referring to the comparatively high number who received either the Moderna or the Pfizer vaccine, as opposed to the Johnson and Johnson shot. “We believe that we’ll probably have a solution for the remainder in the not-too-distant future.”
Getting a third dose does not mean that immunocompromised patients should abandon infection prevention measures, said the CDC’s Kathleen Dooling, MD, who also spoke at the meeting. These measures include wearing a mask, staying six feet away from people outside one’s household, and avoiding “crowds and poorly ventilated indoor spaces until advised otherwise” by a health care provider. She also said that close contacts of immunocompromised people should be vaccinated.
Dr. Dooling presented data showing that the rate of antibody responses to two mRNA vaccine doses ranged from 45% to 95% in studies of people with cancer, with lower response rates seen in patients with blood cancers. The rate of antibody responses ranged from 95% to 100% in healthy people getting the vaccines. Studies in immunocompromised people – so far mainly in those who have received solid organ transplants or are on dialysis – have indicated that getting an additional mRNA COVID-19 vaccine dose “enhances antibody response and increases the proportion who respond to COVID-19 vaccine,” Dr. Dooling said. No studies exist to date on vaccine efficacy or effectiveness at preventing COVID-19 after a third dose, she added. Dr. Dooling also said that small studies of the safety of third doses of the vaccines did not turn up concerning data and that reactions to third doses appeared similar to those from prior doses.
The CDC will continue to monitor the impacts of third doses in immunocompromised people. The CDC’s Karen Broder, MD, noted that soon, people who receive an additional vaccine dose will be able to note this in v-safe, the CDC’s voluntary smartphone-based health check-in tool. V-safe allows people to report any side effects they have after vaccination.
People who presented at the meeting who have direct experience with the challenges immunocompromised people have faced during the pandemic also expressed their support for the additional dose. ACIP member Camille N. Kotton, MD, an infectious disease clinician at Massachusetts General Hospital in Boston who works with patients who have received solid organ transplants or who have cancer, voiced the seriousness of the pandemic for her patients. “Pretty much every week I’ve known of patients who are immunocompromised and in the hospital,” she said. “They did all the right things. They are just suffering from a lack of good vaccine protection.”
A 44-year-old ovarian cancer survivor who spoke during the public comment portion of the meeting said that she had been grateful to get her Pfizer vaccination between chemotherapy cycles this past winter. But reading about reduced vaccine response in immunocompromised people had left her anxious. She said that she was most likely to live two to three more years. “My life ambitions are humble,” she said. But her concern about getting COVID-19 has made it more difficult to meet simple goals, like seeing friends or grocery shopping. Brayton thanked the committee for the potential opportunity to get an additional vaccine dose. “While I understand I will still need to be cautious, I am hopeful for the peace of mind and greater freedom a third shot can provide,” she said.
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