Among hospitalized patients with COVID-19, a new study found that vaccinated patients had a significantly higher risk of mortality, suggesting vaccination may not prevent severe outcomes among hospitalized patients.
Researchers measured antibody levels of patients with SARS-CoV-2 infection and compared antibody levels of vaccinated and unvaccinated patients to determine whether vaccination protected against COVID-19-associated acute respiratory failure and improved outcomes of hospitalized patients.
Of 152 adults admitted to Ohio State University Hospital with acute respiratory failure between May 2020 and November 2022, 112 tested positive for COVID-19 and 40 tested negative. Of the 112 patients with COVID-19, 89 were unvaccinated and 23 were vaccinated. Of the 89 unvaccinated patients, 46 were admitted before COVID-19 vaccines were available, and 43 were admitted after.
Key Findings
- In unvaccinated patients aged 19 to 49 and 50 to 79, researchers observed similar survival outcomes—with a decrease in survival noted in adults older than 80.
- In patients aged 50 and older, an increased risk of mortality was observed in those who were vaccinated compared with those who were not.
- COVID-19 patients who received a complete vaccination series had higher mortality than those who didn’t finish their vaccination series.
- Vaccinated patients who didn’t survive had “significantly increased average time” between receiving their initial vaccine dose and hospital admission compared with patients who did survive.
According to the study, several factors could explain the findings. For example, vaccinated patients tended to be less healthy—a finding supported by the methodology used during the study. Additionally, vaccinated individuals were slightly older. Yet even when patients with similar characteristics were compared, researchers still observed significantly improved survival among unvaccinated patients.
Researchers Surprised by Decreased Antibody Levels in Vaccinated
To their surprise, the researchers observed worse clinical outcomes and decreased antibody levels among vaccinated patients compared with the unvaccinated group. Antibody levels have been the determining factor used by vaccine makers and U.S. regulatory agencies to determine whether a COVID-19 vaccine is effective.Furthermore, researchers observed reduced SARS-CoV-2-reactive antibody levels in vaccinated nonsurvivors.
An antibody is a protein produced by the body’s immune system that circulates in blood, recognizes foreign substances such as bacteria and viruses, and neutralizes them. After exposure to an antigen—a toxin or foreign substance—antibodies continue circulating in the blood to protect against future exposure to the virus or bacteria.
In their study, the researchers measured total IgG4 antibody levels in vaccinated and unvaccinated patients and found higher concentrations in COVID-19 patients in week three, along with reduced protective antibody responses, indicating the higher IgG4 levels didn’t necessarily yield protection against COVID-19. This is consistent with recent studies suggesting mRNA vaccines may increase COVID-19 spike-specific IgG4 levels without providing protection.
However, the authors of the current paper noted that other studies have found benefits to vaccination for hospitalized COVID-19 patients and that IgG4-related noninfectious diseases are more prevalent in patients older than 50 years, which could contribute to increased mortality. At the same time, the higher mortality rates observed among vaccinated patients older than 50, compared with unvaccinated patients with severe COVID-19 and respiratory failure, are concerning and may indicate an impaired response to COVID-19 vaccines, the authors said.
