In an air-handling system that provides cooled air to occupants of a building, most of the air is returned from the space back to the air handler to be reused. This is called â¦ Return Air, or RA. However, some fresh air (called Outside Air, or OA) must be mixed in.
Polio is a viral infection that can cause permanent paralysis. The inactivated poliovirus vaccine (IPV) is usually given at ages 2 months, 4 months, 6â18 months, and 4â6 years. Though the oral poliovirus vaccine (OPV) is still used in many parts of the world, it has not been used in the United States since 2000.
The polio vaccine has gone through a rigorous process of testing by the WHO and the Government of India. There is no problem with the vaccine. However, sometimes, a drop in the efficacy, or effectiveness, of the vaccine may occur if it has not been maintained at the recommended temperature, as is the national protocol.very child during the first year of life should receive at least three routine doses of Oral Polio Vaccine (OVP). However, OPV is not 100 per cent effective. Even children who have received all routine doses and pulse polio doses can get the disease.