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Being fully vaccinated was associated with better survival for patients intubated for acute respiratory distress syndrome (ARDS) owing to COVID-19, a small multicenter study from Greece showed.

In a cohort involving 265 consecutive patients needing intubation for COVID-19 ARDS, mortality was 61.5% for those who were fully vaccinated versus 68.2% for controls who were not fully vaccinated, a significant difference after adjusting for confounders (HR 0.55, 95% CI 0.32-0.94, P=0.03), reported Ilias Siempos, MD, of the National and Kapodistrian University of Athens Medical School, and colleagues.

"An explanation of this finding is hindered by the small number of patients in the full vaccination group," Siempos and colleagues wrote in , as just 26 of the patients were fully vaccinated.

"The fact that this number was small might be not surprising given that vaccination prevents severe illness requiring intubation," Siempos and colleagues contended. At the start of the study (June 7, 2021) only were fully vaccinated, which grew to 70% by study end (Feb. 1, 2022).

"Even on the third day after intubation, oxygenation was higher in the full vaccination group than in the control group." An important finding, the researchers noted, "because evidence both before and during the COVID-19 era showed that, among patients with ARDS, oxygenation on the third day after intubation may be more strongly associated with mortality than oxygenation on the day of intubation."

Of note, those who had completed their primary vaccination series more than 5 months prior to intubation were not considered "fully vaccinated," as this is when the CDC would recommend that these individuals receive a booster dose, the authors noted. So the control group of 239 patients included one partially vaccinated individual, and 32 individuals that had been vaccinated more than 5 months before requiring intubation -- so-called "remotely vaccinated individuals.

Multiple sensitivity analyses supported the main finding, including when restricted to patients who only got mRNA vaccines, and when fully vaccinated patients were compared to those who were completely unvaccinated or to those that had completed their vaccination more than 5 months before intubation.

"One conjecture is that full vaccination, even when it fails to fully prevent the development of ARDS, may still attenuate its severity," the group noted. "This conjecture is supported by the observation that patients in the full vaccination group had better (albeit statistically nonsignificant) lung mechanics and higher oxygenation (i.e., less severe ARDS) at baseline than patients in the control group."

The study involved a total of 265 intubated patients from three Greek ICUs. Patients had a median age of 66 years, and 64.2% were men. Of the 26 fully vaccinated patients, 20 received Pfizer's mRNA vaccine and six received AstraZeneca's.

Fully vaccinated patients were older than the controls (median age 72.5 vs 66 years) and were more likely to have comorbidities (92.3% vs 66.9%, respectively). While not a statistically significant difference, more patients in the fully vaccinated group had mild or moderate ARDS (56% vs 43.3%, P=0.14).

Between-group differences in secondary outcomes -- including length of ICU stay, length of hospital stay, use of vasopressors or vasopressor-free days, and others -- were not significantly different.

Researchers noted that vaccinated survivors had bacteremia in 57.1% cases, as compared to 73.9% in the control group. "Although statistically insignificant, this difference in occurrence might be associated with different mortality rates between groups," Siempos and colleagues suggested.

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