Vaccine Boosters Essential for Immunocompromised Individuals: New Research Reveals

According to a groundbreaking study from the University of Cambridge, vaccinations alone may not be sufficient to protect individuals with compromised immune systems from severe COVID-19 infections, despite their bodies generating antibodies. Findings published in Science Advances suggest that regular vaccine boosters are crucial for these individuals to maintain protection and reduce the risk of infections contributing to new variants of concern.

The Impact of Vaccination on Immunocompromised Individuals

During the COVID-19 pandemic, the rapid rollout of vaccines prevented nearly 20 million deaths, although over 15 million individuals succumbed to the virus. Immunocompromised individuals, whose immune systems do not function correctly, often require medication to suppress their immune response, were found to have difficulty clearing the SARS-CoV-2 virus, even after vaccination. This extended viral presence offers the pathogen ample time to mutate and possibly spawn new variants.

The Importance of Seroconversion

When individuals are vaccinated, their immune systems produce antibodies that target and eliminate the virus following a process called seroconversion. Additional booster doses enhance this process, increasing the likelihood of successfully clearing the infection. Researchers at the Cambridge Institute of Therapeutic Immunology and Infectious Disease (CITIID) investigated immunocompromised patients with vasculitis, a condition requiring immunosuppressant medications, to assess the effectiveness of vaccinations.

Chronic Infections and Variant Emergence

Preliminary research indicated that chronic infections can lead to the creation of new variants with the potential to trigger further infection waves in the general population. In a recent study involving vasculitis patients treated with immunosuppressants, scientists compared their outcomes with those of non-immunocompromised individuals. Despite generating antibodies, fully vaccinated immunocompromised individuals were still hospitalized, admitted to intensive care units, and succumbed to the virus at higher rates.

Multiple Doses May Be Necessary

Researchers at CITIID analyzed blood samples from immunocompromised patients with vasculitis, observing that seroconversion alone did not always neutralize the virus. To achieve adequate protection against a range of variants, including Omicron, these individuals required at least three vaccine doses. In certain cases, even four vaccinations were insufficient to provide complete protection.

Expert Opinions

We know that immunocompromised individuals are particularly vulnerable to diseases such as Covid-19 because their immune systems struggle to clear infections. Vaccinations offer some protection, but our study shows that only repeated vaccinations—often four or more—offer the necessary protection.”

Kimia Kamelian, a Gates Cambridge Scholar at CITIID and St. Edmund’s College, Cambridge

According to Professor Ravi Gupta from CITIID and Homerton College, Cambridge, such findings are significant. “The implications are twofold,” he explains. “Immunocompromised individuals face an increased risk of prolonged infections and severe disease, but they also pose a greater risk of viral mutation and the emergence of new variants.”

Funding and Acknowledgments

This vital research benefitted from funding from Wellcome, Gates Cambridge, Addenbrooke’s Charitable Trust, and Vasculitis UK. The National Institute for Health and Care Research Cambridge Biomedical Research Centre also provided support.