Which of these vaccines are made from a modified bacterial toxin?

The vaccines made from modified bacterial toxins are known as toxoids. Tetanus and diphtheria vaccines are both examples of toxoid vaccines, which are created by inactivating the toxin produced by the bacteria that causes disease. The process ensures that the immune system can recognize and react to the toxin without the person being exposed to the pathogenic effects of the actual bacteria.

In the case of the tetanus-diphtheria (TD) vaccine, it specifically uses inactivated forms of the toxins produced by the Clostridium tetani (tetanus) and Corynebacterium diphtheriae (diphtheria) bacteria. This allows the body to produce an immune response that will protect against future exposures to these bacterial toxins.

Other vaccines listed do not utilize modified toxins. For instance, the influenza vaccine is made using inactivated or attenuated virus particles. The Hepatitis A vaccine is made from inactivated virus, while the MMR vaccine (measles, mumps, rubella) consists of live attenuated viruses. Therefore, the tetanus-diphtheria vaccine is the only one among the given options that fits the criteria of being made from a modified bacterial toxin.