The impact of vaccination status on post-acute sequelae in hospitalized COVID-19 survivors using a multi-disciplinary approach: An observational single center study

Background: COVID-19 vaccines reduced mortality, hospitalizations and ICUs admissions. Conversely, the impact of vaccination on Long COVID-19 syndrome is still unclear. This study compared the prevalence of post-acute sequelae at short and long-term follow-up among hospitalized unvaccinated and vaccinated COVID-19 survivors through a multidisciplinary approach. Methods: After 2 months from discharge, unvaccinated and vaccinated COVID-19 survivors underwent a follow-up visit at a dedicated “post-COVID-19 Outpatient Clinic”. The follow-up visit included a cardiovascular evaluation, blood tests, chest computed tomography, 6-min walking test (6MWT), spirometry. A one-year telephone follow-up was performed to assess re-hospitalizations, death and long-lasting symptoms. An additional 1:1 case-control matching analysis adjusted for baseline characteristics was performed. Results: Between June 2020 and June 2022, a total of 458 unvaccinated and vaccinated patients (229 per group) underwent the follow-up visit. Vaccinated patients had lower rates of ICU admissions (1.7 % vs 9.6 %, p= <0.001) and severe respiratory complications requiring intubation (1.3 % vs 7 %, p = 0.002) or non-invasive ventilation such as high-flow nasal oxygen therapy (1.7 % vs 7.9 %, p = 0.02), CPAP (1.3 % vs 20.1 %, p= < 0.001), and low-flow oxygen therapy (3.5 % vs 63.3 %, p= <0.001) compared to unvaccinated ones. At 2-month follow-up, vaccinated patients had fewer persistent ground-glass opacities (2.6 % vs 52.8 %, p= <0.001) or consolidations (0.9 % vs 8.3 %, p= <0.001). Additionally, unvaccinated patients experienced more frequent myocarditis (4.8 % vs 0.9 %, p = 0.013) and pulmonary embolism (1.8 % vs 0 %, p = 0.042) and exhibited more significant respiratory impairment as evidenced by desaturation during the 6MWT(10.2 % vs 3.5 %, p = 0.005) and altered spirometry (14 % vs 8.7 %, p = 0.043) compared to vaccinated ones. At one-year, unvaccinated patients reported more symptoms such as dyspnea (20.5 % vs 10 %, p = 0.002), psychological symptoms (10 % vs 3.5 %, p = 0.005) and chronic rhinosinusitis/cough (6,6 % vs 2,6 %, p = 0.04) as compared to vaccinated ones. The 1:1 case-control matching analysis also confirmed these results. Conclusions: COVID-19 vaccines improve short-term outcomes and may reduce Long COVID-19 prevalence.