Oxygen is taken into the lungs.
Bacteria:<span>They are much smaller than </span>bacteria<span>, and can be seen only with electron microscopes </span>
CDC conducts studies each year to determine how well the flu vaccine protects against flu illness. <span>While vaccine effectiveness can vary,</span> recent studies show vaccine reduces the risk of flu illness by about 50% to 60% among the overall population during seasons when most circulating flu viruses are like the vaccine viruses.
Answer:
Acute illnesses generally develop suddenly and last a short time, often only a few days or weeks. Chronic conditions develop slowly and may worsen over an extended period of time—months to years.
Explanation:
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