In some cases, these vaccines use epitopesâthe very specific parts of the antigen that antibodies or T cells recognize and bind to. Because subunit vaccines contain only the essential antigens and not all the other molecules that make up the microbe, the chances of adverse reactions to the vaccine are lower.
Tornadoes occur in many parts of the world, including Australia, Europe, Africa, Asia, and South America. Even New Zealand reports about 20 tornadoes each year. Two of the highest concentrations of tornadoes outside the U.S. are Argentina and Bangladesh.
Tornadoes tend to occur in the middle latitudes in both hemispheres, between 30Â° and 50Â°. These latitudes are regions where the warmer subtropical warm air meets the colder polar air, with different wind speeds and direction. These conditions can produce rotating air masses. Tornadoes most frequently occur in the United States, which sees about 1,000 per year. The tornadoes usually occur in the southeastern state of Florida or in Tornado Alley, the central part of the country (Midwest) where most of the violent tornadoes occur. Canada is a distant second with about 100 per year. Twenty to thirty tornadoes per year are reported in New Zealand.