 Vaccines are considered one of the greatest public health achievements of the last century, having eradicated smallpox, a scourge that killed hundreds of millions of people, and greatly reducing other major diseases such as measles and polio. To this day, vaccines are estimated to save millions of lives a year. More than 90% of U.S. children get common childhood vaccinations, such as polio or their measles, mumps, and rubella shot, but most adults fail to get their full complement of recommended adult vaccinations. Assuming you've got all your childhood vaccinations, and aside from any emergent pandemic needs, the CDC recommends all healthy adults get annual flu shots, tetanus boosters every 10 years, though the World Health Organization doesn't think this is necessary, shingles vaccination at age 50, and pneumonia vaccine at age 65. Certain groups need others, such as a Hepatitis B series for healthcare workers, or men who have sex with men, ask your medical professional for a personalized schedule. How safe are vaccines? In a systematic review and meta-analysis, the RAND Corporation screened more than 50,000 citations and concluded that routine vaccinations can be considered safe with only rare serious adverse effects, such as severe allergic reactions in 1 to 10 in a million, and transient autoimmune syndromes, Guillain-Barre, an immune thrombocytopenic perpura in 1 to 3 in a million, and 10 to 30 in a million for flu shots, and MMR vaccines, respectively. Of course, any adverse effect should be weighed against any protective effects that vaccines may provide. In my last video, I talked about the effectiveness of flu vaccines. What about pneumonia vaccines? Pneumonia may well be called the friend of the aged, or the father of modern medicine, Sir William Osler, over 100 years ago in 1898. Taken off by it in an acute short, not often painful illness, the old man escapes those cold gradations of decay, so distressing to himself and to his friends. The thought was that pneumonia mercifully killed those who would soon die anyway, from potentially a more protracted painful illness. But these days, healthy older adults hospitalized for pneumonia are not significantly more likely to die in the subsequent two years than younger adults in the same situation. Because of comorbidities at older ages, though, pneumonia is the fourth leading cause of death in the world, and the ninth leading cause in the United States. The most common cause of community-acquired pneumonia, as opposed to hospital-acquired, is a bacteria known as pneumococcus, or streptococcus pneumoniae. In addition to pneumonia, pneumococcus can cause inner ear infections, sinusitis, or pink eye. It gets serious when it starts to invade the bloodstream, which can result in meningitis, infection of the brain, endocarditis, infection of the heart valves, or sepsis, a life-threatening organ dysfunction caused by blood poisoning. Thankfully, we have vaccines against pneumococcus. The first was developed over a century ago, but they fell out of favor after penicillin was discovered, thinking antibiotics would eliminate the threat. Unfortunately, these days up to 40% of these kinds of streptococcal infections are resistant to at least one antibiotic, and despite our miracle drugs, mortality rates of invasive pneumococcus in the elderly remain around 15 to 30%. However, randomized controlled trials have found that pneumococcus vaccines reduce the risk of those 65 and older, getting pneumococcal pneumonia by 64%, and even more importantly, your risk of invasive pneumococcal disease by 73%. Like the flu vaccine, population studies have found that pneumonia vaccines can reduce the risk of both heart attacks and the overall risk of dying, but unlike flu vaccines, there aren't randomized controlled trials to confirm these bonus benefits.