96% of participants with severe symptoms had sustained immunoglobulin G antibodies up to six months after initial infection, compared to 79% of asymptomatic carriers.
The study's lead researcher said people are often diagnosed based on what they themselves tell medical professionals, and if they no longer feel cravings, they may believe they no longer need treatment, but that may not tell the whole story.
To be eligible, participants should not already be taking probiotics regularly, they must have tested positive for COVID at least four months ago, and they cannot yet have been vaccinated.