COVID-19: down but not out

More than four years have ensued since the start of the COVID-19 pandemic, and while officially, the WHO has declared the end of COVID-19 as a global health emergency,1 we continue to deal with surges of the disease as it finds its place as an 'endemic' respiratory virus. For example, Singapore saw several surges of the virus in 2023, driven by immune escape with novel viral variants (XBB subvariants from March to May, and HK.3 and JN.1 from October to December), waning overall immunity, and normalisation of social interactions and travel. The American philosopher and essayist George Santayana said, "Those who cannot remember the past are condemned to repeat it".2 It is thus crucial that lessons learnt from the pandemic are documented, and this is the impetus for this supplement issue on COVID-19. The unprecedented COVID-19 pandemic was caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which has behaved quite differently from its other zoonotic predecessors SARS-CoV (emerged in 2003) and Middle East respiratory syndrome coronavirus (emerged in 2012) in terms of biological characteristics and scale, including atypical clinical manifestations, some of which are reported in this issue.3,4,5 Besides this, COVID-19 also posed numerous challenges to health systems,6 including control and management in congregate living settings such as dormitories that house migrant workers,7,8,9 as well as the well-being and training of health professionals.10,11,12,13,14,15,16 Further, even though evidence-based therapies for COVID-19 were made available with the first antiviral remdesivir approved for use under emergency authorisation (in Singapore, this was under the pandemic special access route) within a year of the start of the pandemic, healthcare professionals had to continually review evidence for treatment, combat misinformation, and in some instances, conduct studies to evaluate therapies that were promulgated by some quarters but were eventually not substantiated.17,18 Indeed, COVID-19 threw out a couple of surprise 'twists' and 'turns' as the world navigated the pandemic. While we will do well to remember not to 'fight the last war' when the next Disease X comes on the scene, the lessons learnt during the COVID-19 pandemic will hopefully not be so quickly and easily forgotten, but put us in better stead.