Not all COVID-19 pandemic waves are alike

Area of Science:

• Epidemiology
• Infectious Diseases
• Public Health

Background:

• The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic presented distinct waves of infection.
• Understanding patient demographics and outcomes across these waves is crucial for public health strategies.

Purpose of the Study:

• To compare patient profiles and in-hospital mortality between the first and second surges of SARS-CoV-2 in Barcelona, Spain.
• To identify factors influencing mortality differences across pandemic waves.

Main Methods:

• Prospective data collection from adult patients diagnosed with SARS-CoV-2 via nasopharyngeal swab PCR.
• Comparison of patient characteristics and outcomes between two defined pandemic surges (March-August 2020 and August-December 2020).

Main Results:

• The second surge involved younger patients with fewer comorbidities and a shorter symptom-to-diagnosis interval.
• All-cause in-hospital mortality significantly decreased in the second surge (2.8%) compared to the first (8.8%).
• Older age, male sex, comorbidities, ICU admission, mechanical ventilation, and being in the first surge were predictors of in-hospital mortality.

Conclusions:

• Patients infected during the first SARS-CoV-2 wave experienced more than double the in-hospital mortality compared to the second wave.
• The observed differences in mortality are likely multifactorial, reflecting evolving patient profiles and potentially improved clinical management.