If you’ve been following the mystery of long Covid since it emerged in 2020, you’ll recall interferons and serotonin have been clues from the start as combatants in the body’s prolonged battles against the virus. Theories about why symptoms persist long after the acute infection has cleared often point to two suspects: viral reservoirs where SARS-CoV-2 lingers and inflammation sparked by the infection that doesn’t subside.
New research published on Monday in Cell implicates both interferons and serotonin in long Covid in a way that brings together those hypotheses and could also explain “brain fog,” or the neurocognitive difficulties people endure. A team led by researchers from the University of Pennsylvania concludes that when long Covid depletes peripheral serotonin — the kind that circulates in our bodies and not just the brain — that deficit impairs memory and other brain functions. The authors hope further research will lead to testing potential treatments.