麻豆传媒

Long COVID was less likely to occur in healthcare workers who had received two or three mRNA COVID-19 vaccine doses compared with those who weren't vaccinated, an observational study in Italy showed.

Among hospital workers infected with SARS-CoV-2, long COVID prevalence was 41.8% for those who were unvaccinated, 30% with one vaccine dose, 17.4% with two doses, and 16% with three doses, according to Maria Rescigno, PhD, of Humanitas Research Hospital in Milan, Italy, and co-authors.

Lingering symptoms were more common in people infected during the first wave of the pandemic than later periods, but no statistically significant association with infection wave was found, Rescigno and colleagues reported in .

"Our multivariable logistic regression analysis revealed that the number of vaccination doses and not the variant was associated with a reduced prevalence of long COVID," Rescigno told 麻豆传媒.

"Long COVID can happen even among vaccinated individuals and can affect nearly every organ system," observed Ziyad Al-Aly, MD, of Washington University in St. Louis, who wasn't involved with the research.

"Everyone is at risk," Al-Aly told 麻豆传媒. "The most optimal strategy is to avoid infection or reinfection in the first place."

"We cannot rely on vaccination as a sole mitigation; we must develop additional layers of protection to prevent and treat long COVID," said Al-Aly, who led a recent study that showed a 15% among U.S. veterans after vaccination."This is very important and should be a national priority."

Rescigno and colleagues studied 2,560 healthcare workers in nine Italian healthcare facilities from March 2020 to April 2022. Their analysis spanned three COVID waves: February-September 2020 when wild-type SARS-CoV-2 peaked, October 2020-July 2021 when Alpha was the variant of concern, and August 2021-March 2022 when Delta and Omicron were dominant.

Hospital personnel had polymerase chain reaction (PCR) tests for SARS-CoV-2 every week in COVID wards and every 2 weeks in other wards, or if they developed symptoms or were exposed to cases. All workers were required to have three doses of BNT162b2 (Pfizer-BioNTech) mRNA vaccine. First and second doses were administered in January-February 2021; a booster was given in November-December 2021.

From February to April 2022, participants completed surveys about demographics, comorbidities, SARS-CoV-2 symptoms at the time of infection, and symptom duration.

The researchers defined long COVID as at least one SARS-CoV-2-related symptom lasting more than 4 weeks. People who were hospitalized with COVID were excluded from the study.

Overall, 739 healthcare workers had COVID-19, including 89 who were asymptomatic. In total, 229 people (31%) with a mean age of about 44 had long COVID. Older age, higher BMI, allergies, and obstructive lung disease were associated with persistent COVID symptoms.

With a reference group of unvaccinated women in the first wave of the pandemic who had no allergies or comorbidities, odds of long COVID were lower for:

• Men (OR 0.65, 95% CI 0.44-0.98, P=0.04)
• People with two vaccine doses (OR 0.25, 95% CI 0.07-0.87, P=0.03)
• People with three vaccine doses (OR 0.16, 95% CI 0.03-0.84, P=0.03)

The time between the second vaccination dose and infection was not tied to long COVID risk (OR 0.66, 95% CI 0.34-1.29), Rescigno and co-authors noted.

The study was limited by self-reported symptoms and data, the researchers acknowledged. Causality cannot be inferred.

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