New chicken pox vaccine approved

Healthfacts, June, 1995

The chicken pox vaccine is now available, despite doubts raised by some experts about the merits of mass immunization for a relatively minor childhood illness. The vaccine was developed over 13 years ago to protect high-risk children, such as those with

AIDS and leukemia, from severe, potentially fatal, complications. But a continuing controversy over its necessity for healthy children delayed the vaccine's approval.

In March, the FDA approved the licensure of a live attenuated varicella (chicken pox) vaccine; and last month wide acceptance was guaranteed when the American Academy of Pediatrics announced that it should be given to all children, aged one to 18 years, who haven't had chicken pox.

Opponents of universal immunization are concerned about the long-term safety and effectiveness. Proponents insist that chicken pox is not always a minor illness, accounting for 56 deaths in otherwise healthy children and more than 9,900 hospitalizations annually. But a physician at the Centers for Disease Control and Prevention who preferred to remain anonymous said in a telephone interview that the varicella-related deaths and complications were not the main consideration for development of the new vaccine. It was driven by economic considerations that took into account the number of workdays lost by parents who must stay home with a sick child.

The most serious concern raised by the consumer-led National Vaccine Information Center is the unknown long-term effects. (No studies of children given the chicken pox vaccine have followed participants longer than ten years.) That's an understandable concern, and one that is raised with the introduction of almost all new childhood vaccines and shown to be incorrect, said Neal Halsey, M.D. of the American Academy of Pediatrics committee on infectious disease.

The end result has been a marked protection against the diseases of children, and subsequently of adults, he continued. You can't expect to have 20 years of followup on something that's brand new. This is true of any other new drug or new surgical procedure. With most new vaccines, the children have been followed for only about three or four years.

The debate over the chicken pox vaccine's usefulness for healthy children made the front page of The New York Times two years ago. Do you want to give a vaccine with unknown side effectsto prevent a very mild disease? asked Philip Brunnell, head of pediatric infectious disease at Cedars Sinai Hospital in Los Angeles in the 1993 Times interview. If parents' lost work is the problem, then maybe we should send the children back to school sooner, he said, noting that many schools won't permit the child to return before the lesions disappear completely, though most feel well enough far earlier. Ironically, the disease is most contagious before the rash appears. Dr. Brunnell and other experts were quoted in the article as agreeing with this statement: To justify vaccinating everyone against a disease that for most is more inconvenient than harmful, the shot itself must be unquestionably safe.

Today, Dr. Brunnell has changed his mind. Now that it's licensed, I think everyone should be vaccinated, he said in a recent telephone interview. To have a partially immunized population is bad because it would increase the likelihood of susceptible adults who would get the disease when it's more severe. He conceded that the unknown long-term effects are a concern. For example, there is a question of whether this live, though weakened, strain of the varicella zoster virus is more likely to be reactivated later in life and cause the painful rash known as shingles.

The National Vaccine Information Center contends that this is yet another example of an immunization that could backfire. The vaccine may be effective only for a limited time, perhaps ten years, which could have the effect of shifting chicken pox to adulthood when it poses serious risks, such as pneumonia and inflammation of the brain.

This has already occurred in some people given the measles vaccine. Before this vaccine was introduced in 1957, virtually everyone got measles in childhood; the disease rarely occurred in adults and infants under age one when serious complications are more likely. For the first year of life, infants were protected by maternal antibodies they had received via the placenta.

Although the measles vaccine was supposed to have wiped out measles, an outbreak began in 1989. Ninety deaths from measles occurred in 1990 alone. Low immunization rates in some inner-city populations were widely cited as the cause, but 40% of the cases occurred in appropriately vaccinated children (Pediatrics, 5 November 1991). In 1990, the largest increases in incidence rates were among children under one year of age (137%) and adults more than 25 years of age (130%), according to the U.S. Centers for Disease Control and Prevention (JAMA, 26 June 1991). The National Vaccine Information Center called the public's attention to a major reason for the increase in measles among infants: their vaccinated mothers were unable to pass on protective antibodies.