from another source: > The authors concluded that a single 200-mg dose of doxycycline given within 72 hours of a bite from an I. scapularis tick was 87 percent

from another source: > The authors concluded that a single 200-mg dose of doxycycline given within 72 hours of a bite from an I. scapularis tick was 87 percent effective in preventing the development of early Lyme disease https://www.aafp.org/pubs/afp/issues/2002/0215/p714a.html https://www.aafp.org/pubs/afp/issues/2002/0215/p714a.html