On Oct. 25, 2021, the U.S. Centers for Disease Control and Prevention (CDC) updated its COVID-19 vaccine guidance for moderately to severely immunocompromised people over the age of 18 years to include a total of four doses of a COVID-19 biologic.1
Moderate to Severely Immune Compromised People Can Get A Fourth COVID Shot Six Months After Primary Series
The CDC’s new guidance states that moderately to severely immunocompromised people can receive a COVID booster shot at least six months after getting the primary vaccine series, which for the immunocompromised consists of three doses.2
COVID biologic dosing/series is different for immunocompromised individuals than for the general population. In August 2021, the CDC recommended that immunocompromised people who received the two dose series of either the experimental Pfizer/BioNTech or Moderna/NIAID mRNA biologics should also get a third dose of an mRNA biologic.3 4
Federal guidelines stipulated the third dose should be from the same vaccine manufacturer as the first two administered doses.5 The third dose was also not considered to be a booster shot but an extra dose that is part of the primary vaccine series for immunocompromised people.6
The CDC recommendations for the immunocompromised are also different for the Johnson & Johnson COVID vaccine. Moderately or severely immunocompromised people who received a single dose Johnson & Johnson COVID vaccine primary series are recommended to get a single COVID booster shot (Pfizer/BioNTech, Moderna/NIAID or Johnson & Johnson) at least two months after receiving their initial Johnson & Johnson primary dose.7
Significant Numbers of COVID Breakthrough Cases Are in Vaccinated Immunocompromised People
The CDC has said that data from small studies have shown that fully vaccinated immunocompromised people have accounted for a large proportion of hospitalized breakthrough cases.8 In a U.S study, 44 percent of hospitalized breakthrough cases occurred in immunocompromised people, while in an Israeli 9, 40 percent of hospitalized breakthrough cases occurred in immunocompromised patients.
Immunocompromised people infected with the SARS CoV-2 virus are also more likely to transmit the virus to household contacts.1
Immunocompromised People Fail to Mount an Immune Response After Two COVID-19 Shots
Public health officials have said that immunocompromised people do not mount an adequate immune response after receiving two doses of COVID vaccine, which is why they need a third dose.10
Scientists at John Hopkins University conducted a small study published in the Annals of Internal Medicine with a sample of 30 organ transplant patients, who had been fully vaccinated with two doses of a messenger RNA (mRNA) biologic. Since organ transplant patients take immune suppressing medications to ensure that their body does not reject the transplant, there was concern that they may not be mounting a robust immune response to the COVID vaccine.11
After examining COVID vaccine antibody levels following two doses, scientists found that 24 vaccinated patients had no antibodies against the SARS-CoV-2 virus and six of the patients had very low levels of antibodies.11
The organ transplant patients were then given a third dose of either the Pfizer/BioNTech, Moderna/NIAID or Johnson & Johnson COVID-19 shots. Their antibody levels were tested again two weeks following the administration of the third dose. The findings showed that there was an increase in antibody levels in eight of the patients who had no antibodies after two doses, while six patients, who started off with low levels after two doses, had an increase in antibodies against the SARS-CoV-2 virus.12
The scientists who conducted the study commented on the limitations of the study said:
Limitations of this study include a small and heterogeneous convenience sample and the absence of assays for neutralizing antibody, B-cell memory, and T-cell responses.13
Although only one-third of vaccinated patients, who had not responded to two doses of the COVID shot developed antibodies after the third dose, John Wherry, PhD, director of the institute of immunology at the University of Pennsylvania said:
This is a glass half full versus glass half empty kind of thing. One third is not zero, so it does offer some promise for people that are on immunosuppressant drugs.14
Only Certain Immunocompromised People are Eligible for the Fourth COVID Shot
The CDC states that third and fourth doses of a COVID shot are only recommended for immunocompromised people undergoing organ transplants, are actively receiving treatment for cancer, have advanced HIV infections, or are taking chronic immune suppressing medications.15
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Click here to view References:
1 U.S. Centers for Disease Control and Prevention. Interim Clinical Considerations for Use of COVID-19 Vaccines Currently Approved or Authorized in the United States. Oct. 25, 2021.
2 Lewis R. Some immunocompromised people can receive a 4th Covid shot, CDC says. NBC News Oct. 27, 2021.
4 Edwards E. CDC advisory group recommends extra shot for immunocompromised patients. NBC News Aug. 13, 2021.
6 Lewis R. Some immunocompromised people can receive a 4th Covid shot, CDC says. NBC News Oct. 27, 2021.
7 CDC. Interim Clinical Considerations for Use of COVID-19 Vaccines Currently Approved or Authorized in the United States. Oct. 25, 2021.
8 CDC. Media Statement from CDC Director Rochelle P. Walensky, MD, MPH, on Signing the Advisory Committee on Immunization Practices’ Recommendation for an Additional Dose of an mRNA COVID-19 Vaccine in Moderately to Severely Immunocompromised People. Aug. 13, 2021.
9 Oliver S. Data and clinical considerations for additional doses inimmunocompromised people. CDC July 22, 2021.
10 Syal A, Edwards E. A third dose of Covid vaccine may help protect immunocompromised patients, small study suggests. NBC News June 14, 2021.
13 Werbel W, et al. Safety and Immunogenicity of a Third Dose of SARS-CoV-2 Vaccine in Solid Organ Transplant Recipients: A Case Series. Annals of Internal Medicine 2021; 174(9): 1330-1332.
14 Syal A, Edwards E. A third dose of Covid vaccine may help protect immunocompromised patients, small study suggests. NBC News June 14, 2021.
15 Citroner G. Here’s Who May Need a Fourth COVID-19 Vaccine Dose. Healthline Oct. 28, 2021.