In the context of chemistry, polyvalent describes atoms that can form more than two bonds. In medicine, the term also refers to multiple capacities. It almost always applies to medical measures that can address more than one condition, and these treatments could be vaccines, antivenins that help people recover from more than one type of poisonous bite, or medicines that work against multiple microorganisms.
Numerous examples of polyvalent vaccines exist and more are likely to be developed. The advantage of having multiple vaccinations in a single shot is clear to most people; greater protection for diseases with fewer shots is appealing and may be cheaper. Some of the polyvalent vaccines include those for measles, mumps and rubella (MMR), and for tetanus, diphtheria, and pertussis (TDaP). Alternately, a vaccine can protect against different types of the same disease. Pneumovax® gives protection against 23 germs that may create pneumonia, and Gardasil® should prevent four types of human papillomavirus (HPV), which are most linked to the development of cervical cancer.
Not all vaccines are polyvalent, which may mean they haven’t yet been combined into a multiple form, or mixing them with other vaccines might their reduce effectiveness. Another consideration is the number of times a vaccine must be delivered for full effect. It doesn’t make sense to combine vaccinations that have different timelines for delivery. Combining something that has to be given every six months with something that must be given every ten years wastes medicine.
In contrast to vaccines, antivenin is only given if a person receives a poisonous bite. In areas where there are many poisonous creatures, it’s easy to see why having a polyvalent antivenin that treats for multiple types of bites is highly beneficial. It may be less expensive than a creature-specific antivenin and could reduce difficulties associated with carrying or storing medicines.
Examples of polyvalent antivenins include one made in India that will react against the Spectacled Cobra, Common Krait, Russell’s Viper, and Saw-Scaled Viper. Another type is also available to treat all Iranian scorpion envenomations, and one exists that may reduce sickness after bites from Brown Recluse and Black Widow spiders. A simple antivenin in Australia may work against almost all Australian poisonous snakes.
As with vaccinations, combining different antivenins may be practical or impractical, and it doesn’t always work. Polyvalent antivenins are most practical in areas with larger numbers of poisonous animals, fish, or insects that are likely to come into contact with people. It doesn’t make sense in many instances to combine two or more antivenins, unless need for more than one type is likely to occur often.
Other treatments may effectively kill more than one kind of bacteria or parasite. Most antibacterial medications show polyvalence. There are also many types of vermifuges or antiparasitic medications that will treat more than one type of infection; for instance, a medication could kill roundworms, hookworms, and tapeworms, and be prescribed for any of these infestations.