Main differences between the first and second waves of COVID-19 in Madrid, Spain.

Background: The emergence and rapid global spread of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) represents a major challenge to health services, and has disrupted social and economic activities worldwide. In Spain, the first pandemic wave started in mid-March 2020 and lasted for 3 months, requiring home confinement and strict lockdown. Following relaxation of the measures during the summer, a second wave commenced in mid-September 2020 and extended until Christmas 2020.

Unveiling Long COVID-19 Disease.

The clinical spectrum of "Severe Acute Respiratory Syndrome Coronavirus type 2" (SARS-CoV-2) infection is wider than initially thought. The coronavirus does not establish a chronic cellular infection, in contrast with HIV or the hepatitis B virus, that keeps their genomes, respectively, as proviruses integrated within the chromosomes or as episomes (Soriano et al. J Antimicrob Chemother 2014).