Top 5 Takeaways

  1. Increased Protection for Immunocompromised Adults: The updated 2023–2024 (monovalent XBB.1.5) COVID-19 vaccine offers increased protection against COVID-19-associated hospitalizations for adults aged ≥18 years with immunocompromising conditions.
  2. Low Uptake of the Updated Vaccine: Despite being at higher risk for severe COVID-19, only 18% of the studied high-risk population had received the updated COVID-19 vaccine.
  3. Vaccine Effectiveness Over Time: Vaccine effectiveness (VE) against COVID-19-associated hospitalization was 38% in the first 7–59 days after receiving an updated dose, decreasing slightly to 34% in the 60–119 days following vaccination.
  4. Public Health Implications: The findings underscore the importance of vaccination with the updated COVID-19 vaccine for persons with immunocompromising conditions, including the option for additional doses as per CDC recommendations.
  5. Need for Increased Vaccine Coverage: The low vaccination rates among individuals with immunocompromising conditions highlight a significant opportunity to improve uptake and prevent severe COVID-19 outcomes in this vulnerable population.

Original Article Author and Citation

Corresponding Author

Ruth Link-Gelles,

Suggested Citation

Link-Gelles R, Rowley EA, DeSilva MB, et al. Interim Effectiveness of Updated 2023–2024 (Monovalent XBB.1.5) COVID-19 Vaccines Against COVID-19–Associated Hospitalization Among Adults Aged ≥18 Years with Immunocompromising Conditions — VISION Network, September 2023–February 2024. MMWR Morb Mortal Wkly Rep 2024;73:271–276. DOI:


This MMWR article presents findings on the interim effectiveness of the updated 2023–2024 monovalent XBB.1.5 COVID-19 vaccine against hospitalization due to COVID-19 among adults aged ≥18 years with immunocompromising conditions. The study, conducted by the VISION Network from September 2023 to February 2024, reveals a modest effectiveness of the updated vaccine in this high-risk group, highlighting the ongoing need for vaccination efforts in this population.


The study utilized a test-negative design, analyzing data from hospitalizations among adults with immunocompromising conditions who exhibited COVID-19-like illness and underwent SARS-CoV-2 molecular testing. Vaccine effectiveness was assessed by comparing vaccinated and unvaccinated individuals within this group.


The findings indicate that vaccination with the updated COVID-19 vaccine offers additional protection against hospitalization due to COVID-19 in individuals with immunocompromising conditions. However, the overall low uptake of the vaccine among this population underscores the need for targeted public health interventions to increase vaccination rates.


The updated 2023–2024 COVID-19 vaccine is effective in reducing hospitalizations due to COVID-19 among adults with immunocompromising conditions. Public health efforts should focus on increasing vaccine uptake in this vulnerable population to mitigate the impact of COVID-19.
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