There are a couple of things it means.
A.) From a strictly science perspective, medicines that have been used for worms would need to go through clinical trials to confirm that they can be used to fight infections from viruses. Right now, people using medicines like doxycycline, ivermectin, and hydroxycloroquine to treat viral infections like CoVID-19 are doing so based on limited evidence of the medicines directly stopping the virus.
B.) From a risk perspective, the illnesses for which drugs like hydroxycloroquine, ivermectin, and doxyclyine are prescribed can result in organ damage. In situations like this, the risk of injury from the medicine are considered either less likely or less serious than certain infection with these parasites. Any eyesight damage or organ damage that may come from these medicines is considered less risky than the effects of the parasite infection.
C.) Following B, we have vastly better prescription-only medicines for stopping anti-inflammatory responses here state-side.