Survivors of pertussis epidemics (whooping cough) in the mid-1950s, 1940s and before will recall elementary schools closing to stop the spread. In some communities, almost every child eventually contracted the highly contagious disease, with national numbers of cases peaking around 1955. Although the disease is caused by a bacterium, not a virus, treatment has been difficult and sometimes ineffective then and now. When used soon after infection, erythromycin and other macrolides have been partially effective but can cause difficult side-effects. [ Tejpratap Tiwari, Trudy V. Murphy and John Moran, Recommended antimicrobial agents for the treatment and postexposure prophylaxis of pertussis, U.S. Centers for Disease Control and Prevention, 2005, at ]

While pertussis was not as deadly as tetanus, it was much more common. In the U.S., however, more effective quarantines and improved care during the twentieth century cut the mortality rate around tenfold, by the start of World War II--to about 20 deaths per million residents per year. Nevertheless, the disease progress can be fearful and may take months, so that the introduction of pertussis vaccine to the DTP combination in 1948 (diphtheria, tetanus and pertussis) was generally welcomed and became a standard regimen in pediatrics. By 1960, a further tenfold reduction in U.S. pertussis mortality occurred. [ Vital statistics and health and medical care, Historical Statistics of the United States, U.S. Department of Commerce, 1975, at ]

Although pertussis has long been considered a well controlled disease in the U.S., recent years have seen an upsurge. Over 18,000 cases were reported to state health departments in the first half of 2012. [ Dr. Laurie Handwerker, CDC says pertussis outbreak may be worst in 50 years, ABC News, July 19, 2012, at ]

The relatively short duration of tetanus immunity is widely recognized, with "booster" vaccinations routine for people in hazardous occupations. Similar declines over time in pertussis and diphtheria immunity do not get nearly as much attention. Investigations published so far suggest that about half the population loses immunity against pertussis by four years after vaccination. Nevertheless, few teenagers and almost no adults receive "booster" vaccinations. [Aaron M. Wendelboe, Annelies Van Rie, Stefania Salmaso and Janet A. Englund, Duration of immunity against pertussis after natural infection or vaccination, Pediatric Infectious Disease Journal 24(5):S58-S61, 2005]

Does a balance of risk and benefit favor revaccinating adults and older children? Reactions to DTP vaccines are fairly common and have caused deaths. [ Sandra Tomkins, Vaccine's a lifesaver and a hazard, Fresno (CA) Bee, 1984, first article in a series, archived at ] The whole-cell pertussis vaccine, first introduced in 1904, appears prone to provoke reactions. Newer acellular pertussis vaccines, including two approved by the FDA in 2005 for use with adolescents and adults, appear to be safer, but the immunities they confer may be of shorter durations. [ Mike Stobbe, Associated Press, CDC advisory panel urges whooping cough vaccine for adults, Boston Globe, February 22, 2012, at ]