You may not know it, but you have an army of microbes living inside of you that are essential for fighting off threats, including the virus that causes COVID-19.
In the past two decades scientists have learned our bodies are home to more bacterial cells than human ones. This community of bacteria that lives in and on us – called the microbiome – resembles a company, with each microbe species performing specialized jobs but all working to keep us healthy. In the gut, the bacteria balance the immune response against pathogens. These bacteria ensure the immune response is effective but not so violent that it causes collateral damage to the host.