Oral polio vaccine is highly effective and inexpensive (about US$0.10 per dose, or US$0.30 per child and its availability has bolstered efforts to eradicate polio. A study carried out in an isolated Eskimo village showed that antibodies produced from subclinical wild virus infection persisted for at least 40 years. Because the immune response to oral polio vaccine is very similar to natural polio infection, it is expected that oral polio vaccination provides similar lifelong immunity to the virus.
Contact immunity to polio can occur when attenuated poliovirus derived from the oral polio vaccine is excreted, and infects and indirectly vaccinates unvaccinated individuals.
Sound waves<span> coming from farther above, where it is warmer, will experience a refraction. The change in speed from the warmer </span>air<span> to the cooler </span>air<span> causes a bending effect, as the </span>sound travels<span> downward.</span>
Preserved footprints left behind by animals are called ichnites.
Answer:
Cells are arranged to form different types of TISSUE, which then work to perform specific jobs for the well-being of the animal.
Answer:
Tundra, taiga, coral reef, desert.
Explanation:
