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CDC Data and Clinical Considerations for Additional COVID Vaccine Doses in Immunocompromised People Image
Aug 04, 2021

CDC Data and Clinical Considerations for Additional COVID Vaccine Doses in Immunocompromised People

Mary Knudtson Photo

Mary Knudtson DNSc, NP, FAAN

There has been discussion of whether people with immunocompromising conditions should receive a 3rd dose of the mRNA COVID vaccine. The CDC presented at the Advisory Committee on Immunization Practices (ACIP) meeting on July 22, 2021 regarding the data they have.

As background information, about 2.7% of US adults are immunocompromised. For purposes of the presentation, immunocompromised is defined as:

  • Having solid tumor and hematologic malignancies
  • Recipients of solid-organ or hematopoietic stem cell transplant
  • Having severe primary immunodeficiencies
  • Living with HIV
  • Treatment with immunosuppressive medications such as cancer chemotherapeutic agents, tumor necrosis factor blockers, certain biologic agents (eg, rituximab), and high-dose corticosteroids

Their data showed immunocompromised people are at higher risk of becoming severely ill from COVID-19 than the general population; higher risk for prolonged SARS-CoV-2 infection and shedding were also noted in immunocompromised people. In addition, this population is more likely to transmit SARS-CoV-2 to household contacts and to experience breakthrough infections.

Data on vaccine effectiveness (VE) of the mRNA vaccines in immunocompromised people was also presented:

  • 7 to 27 days after 2nd dose of Pfizer-BioNTech vaccine
    • VE against SARS-CoV-2 infection: 71% (CI 37%-87%) among those with immunosuppression vs 90% (CI 83%-96%) overall
    • VE against symptomatic COVID-19: 75% (CI 44%-88%) among those with immunosuppression vs 94% (CI 87%-97%) overall
  • ≥7 days after 2nd dose of mRNA vaccine (Moderna or Pfizer-BioNTech)
    • VE against SARS-CoV-2 infection among people with inflammatory bowel disease on immunosuppressive medications: 80%
      • In the same population: VE against SARS-CoV-2 infection after 1st dose was 25%
  • ≥14 days after 2nd dose of mRNA vaccine (Moderna or Pfizer-BioNTech)
    • VE against hospitalization for COVID-19: 59% (CI 12%-81%) among those with immunocompromising conditions vs 91% (CI 86%-95%) without immunocompromising conditions

All of the studies they presented showed a lower mRNA vaccine effectiveness for people with immunocompromising conditions than those without.

Lastly, they presented the emerging data on the evidence they have from giving a 3rd mRNA COVID-19 vaccine dose to immunosuppressed people. Notably, with a 3rd dose, 33% to 50% of immunocompromised people developed a seropositive antibody response; these patients had previously demonstrated no detectable antibody response to the initial 2-dose mRNA vaccine series.

France, the UK, and Israel are now already recommending or strongly considering a 3rd dose of mRNA vaccine for people with immunocompromising conditions. The emerging data from the CDC do seem to support this approach.


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