Hog Vaccine Strain Composition
I cannot provide a definitive answer to this question because the evidence provided does not contain specific information about the number of strains in hog vaccines.
What the Evidence Shows
The provided research discusses various aspects of swine vaccines but does not specify a standard strain count:
Influenza vaccines for swine: A quadrivalent neuraminidase RNA particle vaccine (Sequivity®) contains four NA antigens representing major neuraminidase clades of H1N1, H1N2, and H3N2 subtypes circulating in U.S. swine herds 1
Classical swine fever (hog cholera) vaccines: Historical vaccines used single lapinized strains (Rovac, Chinese C-strain, Russian LK-VNIVViM) rather than multivalent formulations 2, 3, 4
PRRSV vaccines: Current vaccines are based on a single PRRSV strain, which has proven inadequate for protection against genetically diverse field strains 5
Critical Context
The number of strains in a hog vaccine depends entirely on which disease the vaccine targets. Different swine pathogens require different vaccine formulations:
- Swine influenza vaccines may contain multiple strains (the example above uses 4) 1
- Classical swine fever vaccines historically used single strains 2, 3, 4
- PRRSV vaccines currently use single strains, though this approach has significant limitations 5
Important Caveat
The evidence provided focuses primarily on human vaccines (influenza, pneumococcal, smallpox) rather than veterinary vaccines for swine. Without access to current veterinary vaccine labels or swine-specific guidelines, I cannot provide the specific strain count you're seeking.