Variability in the Clinical Course of COVID-19 in a Retrospective Analysis of a Large Real-World Database

Abstract

The COVID-19 pandemic proceeds in waves, with variable characteristics of the clinical picture resulting from the evolution of the SARS-CoV-2 virus. This study aimed to compare the epidemiological characteristics, symptomatology, and outcomes of the disease in patients hospitalized for COVID-19 during periods of different variants dominance. Comparing the periods of dominance of variants preceding the Delta variant, the Delta period was characterized by a higher share of hospitalized females, less frequent comorbidities among patients, and a different age distribution. The lowest need for oxygen therapy and mechanical ventilation was observed under Omicron dominance. The triad of classic COVID-19 symptoms, cough, fever, dyspnoea, and fatigue, were most prevalent during the Delta period, and significantly less common under the Omicron dominance. During the Omicron period, nearly twice as many patients as in the previous periods could be discharged from the hospital within 7 days; the overall 28-day mortality was significantly lower compared to that of the Delta period. It also did not differ between periods that were dominated by the BA.1 and BA.2 subvariants. The study indicates that the Omicron SARS-CoV-2 variant that dominated between January and June 2022 caused a disease which resembled the common cold, and was caused by seasonal alpha and beta-coronaviruses with a low pathogenicity for humans. However, one should note that this effect may not only have been related to biological features of the Omicron lineage, but may additionally have been driven by the increased levels of immunization through natural infections and vaccinations, for which we could not account for due to a lack of sufficient data.

Clinical evidence of the effectiveness of remdesivir in COVID-19 during periods dominated by Delta and Omicron SARS-CoV-2 variants.

“…This finding clearly shows the benefits of RDV use during the dominance of this highly pathogenic SARS-CoV-2 variant 33 . However, the mortality in RDV-treated patients was also reduced, approximately 1.5-fold, in the Omicron wave, which was generally characterized by a milder course of infections 21,22,[34][35][36] .…”

“…Similarly to previous research from SARSTer database 21,22 , two periods of variants dominance were established based on sequences submitted by Polish laboratories according to the Global Initiative on Sharing All Influenza Data (GISAID), the most reliable database on SARS-CoV-2 variants prevalence in different regions of the world 23 . Infection of SARS-CoV-2 was diagnosed based on a positive polymerase chain reaction or antigen test result, while management and treatment followed current national recommendations for COVID-19 19,20 .…”

Surfing the Waves: Differences in Hospitalised COVID-19 Patients across 4 Variant Waves in a Belgian University Hospital

“…Second, we decided to include only patients for whom COVID-19 was the main reason for admission. Some researchers have used similar basic inclusion criteria [ 16 ] but could not always tell whether COVID-19 was the main reason for admission [ 9 ], making our data more precise. Third, we used classic severity outcomes once in the hospital (ICU admission, etc.…”

“…Many published studies have focused on data spanning one or a couple of COVID-19 waves at a time [ 6 , 7 , 8 ], but data on the evolution of COVID-19 across waves are scarce [ 9 ]. Our study was set up to analyse the clinical characteristics and severity of patients hospitalised for COVID-19 during the COVID-19 pandemic in a Belgian university hospital.…”

mRNA vaccines: The future of prevention of viral infections?

“…33 The number of deaths averted per administered dose was significantly higher in high-income countries, which has also been attributed to higher access and uptake of the more efficacious mRNA vaccines. 33 Moreover, studies show that scaling up mRNA vaccinations against COVID-19 in lower-to-middleincome countries during the dominance of the clinically less significant Omicron severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variant [34][35][36] would bring substantial benefits in terms of averted deaths and could be an economically reasonable approach. 37 At the same time, mRNA vaccines are well-accepted by individuals who do not reveal significant vaccine hesitancy.…”