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.
Earthquakes and floods constantly crop up in international headlines, but tornadoes often seem like a uniquely American misfortune. In part, that's true: The United States sees the most tornadoes in the world, with an average of more than 1,000 tornadoes each year. Canada is second, with around 100 per year, and all other countries combined experience another 100 to 200 tornadoes annually.