What causes people to suffer from “long covid” symptoms?

The composition of the gut microbiome may be related to a person’s risk of developing “covid long” many months after initial SARS-CoV-2 infection, research published online in the journal Gut suggests. The researchers suggest that microbiome “profiling” could help identify people most likely to develop this disease.

The post-acute syndrome of COVID-19, nicknamed “Long Covid” (persistent), is characterized by complications and/or persistent symptoms weeks and months after the initial COVID-19 infection. It is relatively frequent, since until the recovery from the COVID-19 infection. Fatigue, muscle weakness and insomnia are the most common symptoms.

An exaggerated response of the immune system, cell damage or the physiological consequences of a critical illness can contribute to the development of prolonged covid. But n, or why some people seem to be more susceptible, the researchers say.

There is mounting evidence implicating the gut microbiome – the trillions of bacteria, fungi and other microbes that inhabit the digestive tract – in the severity of COVID-19. And since the gut plays an important role in immunity, a disordered immune response to Covid infection, induced by resident microbes, could affect the recovery process as well.

Therefore, the researchers wanted to find out if the composition of the gut microbiome could be related to prolonged covid, defined as at least a persistent symptom after the elimination of SARS-CoV-2 from the body.

To do this, they have followed the changes in the intestinal microbiome of 106 patients with different degrees of severity of COVID-19, treated in three different hospitals between February and August 2020, and in u, during the same period.

To do this, they analyzed the stool samples of the participants. Among the 106 patients with COVID-19, samples were collected at admission (68), and again after one month (64) and 6 months (68). Samples were also collected from 11 patients 9 months later.

The researchers checked for the presence of the 30 most commonly reported long COVID symptoms 3 and 6 months after initial COVID-19 infection. Aerobic capacity and endurance, an indicator of long COVID, were also measured in a 6-minute walk test.

The mean age of patients with COVID-19 infection was 48 years; slightly more than half were women. The majority (81%) had a mild to moderately severe infection; 25 were treated with antibiotics.

Long covid was reported in 86 (81%) of these patients at 3 months and in 81 (76.5%) at 6 months. The most common symptoms at 6 months were fatigue (31%), forgetfulness (28%), hair loss (22%), anxiety (21%), and sleep disturbances (21%).

such as age, gender, prevalence of underlying conditions, use of antibiotics or antiviral drugs, or severity of COVID-19 among patients with and without long-term Covid, 6 months after initial infection.

Initial viral load

Among the 68 coronavirus patients whose stool samples were tested at six months, 50 had long-standing covid. Although the initial viral load was not associated with long-standing covid, their gut microbiome differed from that of patients without long-term covid and those without covid-19 infection.

These patients had a less diverse and abundant microbiome; the gut microbiome of patients who did not develop the condition was similar to that of those who had not had coronavirus.

Among the bacterial species found in patients with long covid, such as 3 and 6 months after hospital discharge.

At 6 months, patients with long-standing covid had significantly fewer ‘F. prausnitzii’ and ‘friendly’ Blautia obeum and a greater abundance of ‘unfriendly’ Ruminococcus gnavus and ‘Bacteroides vulgatus’ than people who had not had covid.

On the other hand, the gut microbiome of those who did not develop long-term covid only showed 25 changes in bacterial species at the time of hospital admission, and they fully recovered after 6 months.

Next, the researchers analyzed the composition of the to see if it was associated with the different categories of symptoms of prolonged covid: respiratory; neuropsychiatric (headache, dizziness, loss of taste and smell, anxiety, poor concentration, sleep disturbances, low mood, poor memory, blurred vision); gastrointestinal; cutaneous (hair loss); musculoskeletal; and fatigue.

Eighty-one bacterial species were associated with different categories of long covids, and many species were associated with more than two categories of persistent symptoms.

For example, at six months, persistent respiratory symptoms were strongly associated with several “unfriendly” opportunistic microbes, including Streptococcus anginosus, Streptococcus vestibularis, Streptococcus gordonii, and Clostridium disporicum. And several species known to boost immunity, such as ‘Bifidobacterium pseudocatenulatum’, ‘F. prausnitzii’, the ‘R. inulinivorans’ and ‘Roseburia hominis’, were reduced in those with prolonged covid at 6 months.

Similarly, several species of “unfriendly” bacteria were associated with worse performance on the 6-minute walk test among those with long Covid.

At the time of hospital admission, the diversity and richness of the patients’ gut bacteria subsequently developed , suggesting that certain gut microbial profiles may indicate increased susceptibility, the researchers say.

This is an observational study, and as such cannot establish cause, but the results echo other research implicating a disordered gut microbiome in a number of long-term diseases, the researchers say.

“In summary, alteration of the composition of the gut microbiome is strongly associated with the persistence of symptoms in patients with COVID-19 up to six months after the elimination of the SARS-CoV-2 virus –the researchers conclude-. Considering the millions of people infected during the ongoing pandemic, our findings are a strong impetus for consideration of microbiota modulation to facilitate timely recovery and reduce the burden of post-acute Covid-19 syndrome.”