The ASTAR Infectious Diseases Labs (ASTAR ID Labs) and the National Centre for Infectious Diseases (NCID) researchers have published a study in the Journal of Medical Virology, that shows that the extended inflammation observed in COVID-19 patients who were hospitalized is reduced to healthy levels within two years of the first infection.
The impact of Long COVID
Typically, individuals experience COVID-19 symptoms for a few days or weeks following the onset of the first symptoms. However, some people experience symptoms that last for several weeks or more, commonly known as long COVID or aftereffects of SARS-CoV-2 infection. Individuals with long COVID typically report one or more symptoms, such as chronic fatigue, shortness of breath, joint or muscle aches, cough, difficulty concentrating, memory problems, heart palpitations, and insomnia, among others. The exact causes of long COVID are unknown, but it occurs more frequently in people who have had severe COVID-19 or have not been vaccinated against SARS-CoV-2.
ASTAR researchers conducted a study over 24 months to investigate why some people experience long COVID. During the study, doctors at NCID and Changi General Hospital (CGH) recruited 78 individuals who had been hospitalized with COVID-19, some of whom had a severe infections. After leaving the hospital, patients were followed up for up to 24 months to monitor for COVID-19 aftereffects. After the first year, around 37% of the patients reported symptoms.
ASTAR scientists noted that patients who experienced persistent symptoms had ongoing inflammation, with increased blood inflammatory cytokines and abnormal activation of immune responses, for up to 24 months after the first infection. Furthermore, they discovered that older individuals who had more severe outcomes after the initial infection were more likely to experience prolonged systemic inflammation after recovering. However, symptoms that last beyond two years may or may not be linked to COVID-19.
Dr Fong Siew-Wai, Research Scientist at A*STAR ID Labs and lead author of the study, said,
“Our study provides valuable insights into the relationship between COVID-19, inflammation and post-recovery symptoms. It revealed that the immune cells of individuals who experience persistent inflammation show signs of aging. This breakthrough in research helps us better understand the long-lasting effects of COVID-19 experienced by patients. It also opens up new possibilities for developing treatments that specifically target the root cause of these prolonged symptoms.”
Long COVID symptoms expire after about 24 months
In this study, all patients were given one dose of mRNA vaccine after the same infection at 12 to 16 months. Their immune profiles at 12 and 24 months were compared, and the findings showed that patients suffering from long COVID experienced relief from persistent inflammation and immune activation after 24 months. This is because most of the inflammatory markers and dysregulated immune cells recovered to levels comparable to healthy vaccinated individuals. Importantly, the research showed that COVID patients did not experience any worsening of symptoms or increased inflammation after receiving the vaccine. Therefore, it is recommended that long haulers get vaccinated to protect against reinfection.
Associate Professor Barnaby Young, Head of the Singapore Infectious Disease Clinical Research Network at NCID, who led clinical recruitment for this study, said,
“Long COVID is a puzzling and frustrating condition for patients. While research into the condition is gathering pace around the world, it remains poorly understood. We hope our study offers reassurance to sufferers that their symptoms will resolve with time and that it will accelerate the search for a treatment that can speed up recovery.”
