It's almost four years after the start of the COVID-19 pandemic, and for many who were infected with SARS-CoV-2, the impacts of the infection are still lingering. Long COVID is thought to affect millions of people with a wide variety of symptoms that have often mystified clinicians and researchers. But new research may offer hope for long COVID patients. Scientists have tested a drug called SIM01, which delivers strains of bacteria called Bifidobacterium and soluble fibers to promote the growth of the bacteria; they found that this drug can relieve several symptoms of long COVID, also known as post-acute COVID-19 syndrome (PACS). The drug is thought to alter the gut microbiome and possibly the immune system. The findings have been reported in The Lancet Infectious Diseases.
In this study, 463 adult long COVID patients were randomly put in either a group that received SIM01, or a group that received a vitamin C placebo. The volunteers were given a dose two times a day for six months, and the therapy started a median of four months after the start of their infection. Patients were assessed every day to determine their quality of life, symptoms, and activity level. Questionnaires were given and blood and fecal samples were collected after six months.
The researchers determined that those taking the SIM01 drug had a relative improvement in their symptoms of fatigue of 47 percent; for memory-related symptoms, there was a 56 percent improvement; there was a 62 percent improvement in concentration; 30 percent improvement in gastrointestinal symptoms; and for general unwellness, an improvement of 31 percent. There was no significant improvement in quality of life or activity level at the six month point, however,
Adverse events affected both the placebo and the medication group about equally, and none of the reports were thought to be related to SIM01. Other predictors of improvement included Omicron infection (instead of previous variants), milder infections, and SARS-CoV-2 vaccination before infection.
The investigators suggested COVID-19 patients may have significantly lower levels of bacteria that generate short-chain fatty acids, and this could be a major link to the severity of COVID-19 infections. Those who took SIM01 also had a more diverse gut microbiome, fewer antibiotic resistance genes, and carried more bacteria that generate short-chain fatty acids compared to the placebo group.
The relief of specific symptoms was linked to specific aspects of the microbiome.
Increased Bifidobacterium adolescentis bacteria levels were connected to the relief of gastrointestinal issues, memory loss, and fatigue. Increases in Bifidobacterium bifidum were associated with relief of general unwellness and fatigue, and higher Bifidobacterium longum levels were correlated with improvements in concentration.
Now there have been several lines of evidence showing that gut microbiome changes are related to the development of long COVID in some patients. Probiotics and some beneficial microbes could also help relieve symptoms.
Unfortunately, long COVID can still cause such a wide range of symptoms that there is no universal assessment tool for the disorder. This limits the power of the study, because patients and doctors tend to rely on subjective assessments. The researchers also acknowledged that because there was little to no improvement in quality of life at the six-month point, the treatment may not have very significant benefits for many people.
Sources: CIDRAP, Lau et al The Lancet Infectious Diseases 2023, Raman et al The Lancet Infectious Diseases 2023