A few years ago, I attended a lecture by a colleague who believed that autism in children was caused by vaccines.
The peer-reviewed scientific literature tended to discredit this view. Nonetheless, similar public concerns about immunization are widespread, fueled by medical, religious or philosophical concerns. Moreover, many people may have become complacent in recent decades, as memories of measles and poliomyelitis epidemics, for example, fade from public consciousness.
Sadly, we are now seeing resurgences of diseases that were previously, to use a boxing metaphor, “on the ropes.” As the Centers for Disease Control and Prevention ushers in next month’s National Immunization Awareness Month, there is cause for concern.
At least 539 cases of measles were reported in the U.S. so far in 2014, the most since 1994. Nearly 70 percent of cases occurred in unvaccinated people, 20 percent in those with unknown vaccination status, and only 10 percent among those who had been vaccinated. About half of these cases, however, involved adults, with ages up to 65.
Boosting the immunity of adults, for various conditions, is garnering more interest among clinicians. A vaccine for shingles, a nerve condition caused by the chicken pox virus, is now widely advised for those 60 years or older. Tetanus shots often are combined with immunization against pertussis, or “whooping cough.” Pertussis is cropping up more frequently among older patients, recently. I suspect, therefore, that we may see more use of tetanus-pertussis boosters.
When a certain number of families opt out of immunizations, “herd immunity” may protect them. Essentially, immunized people in a population serve to diminish propagation of disease through a broader population that may not be fully protected. Those who are not immunized, in a sense, are protected by their peers who opted in. In the case of some diseases, like polio, the risk of exposure in the U.S. might also be quite modest.
Polio, however, still occurs in underdeveloped countries. Therefore, continued adherence to immunization protocols promulgated by responsible organizations would appear to be essential, if we are to eventually eradicate polio and similar diseases. We are all in this together. The eradication of smallpox is the quintessential example of a successful immunization campaign.
About a third of community-acquired pneumonia cases are due to an organism called pneumococcus. Sir William Osler, a famous physician of the early 20th century, gave this organism the nickname “Captain of the Men of Death.” It is treatable today with antibiotics, but we still see at least 40,000 deaths a year in the United States due to pneumonia.
Some pneumonias are not caused by this organism, but this vaccine still confers benefit on the elderly and those with chronic health conditions. Some children, such as those with sickle cell anemia, may also benefit from this vaccine.
In past decades, protection against hepatitis A involved a painful injection of immunoglobulins, offering temporary protection to travelers going to endemic areas. Now there is a combined vaccine that protects against both hepatitis A and B, and immunoglobulin injections are not routinely employed. New infection rates for hepatitis B in the U.S. decreased 80 percent over the past two decades, due in large part to successful immunization implementation. We still see 40,000 new cases a year, however. Moreover, up to 10 percent of those infected with hepatitis B may become chronic carriers.
The influenza virus circulates in tropical countries throughout the year. Our annual flu shot, therefore, is important. Influenza “pandemics” swept the globe in 1918, 1957 and 1977.
Recall that immunizations are part of a comprehensive health care program, which also includes nutrition, exercise and education. Consult your family physician for specific recommendations. Recall also that with or without immunizations, frequent hand washing is critical for avoiding infectious diseases.
Scott T. Anderson, M.D. (email [email protected]), is clinical professor at UC Davis Medical School. This column is informational, and does not constitute medical advice.