Childhood vaccines in short supply

WHITEHOUSE STATION, New Jersey (CNN) -- A shortage of the critical vaccine that protects children from measles, mumps and rubella has led federal health officials to dip into an emergency stockpile.

It is a step that may be repeated with other vaccines that are getting in shorter supply, officials said.

"It is important for people to understand when it comes to medicines, you need to have access to them when you need them," said Dr. Bruce Gellin of Vanderbilt University, the executive director of the National Network for Immunization. "There is a practical issue here. If the vaccine is not available when you need it, someone needs to keep track and reschedule doctor visits. The confusion and chaos is substantial."

In addition to the measles, mumps and rubella vaccine -- known as MMR -- other vaccines in short supply include Prevnar, which protects against potentially deadly pneumococcal bacteria; DTaP, for diphtheria, tetanus, and whooping cough; and the chickenpox vaccine.

The current vaccine schedule requires children to get at least 20 doses of seven different vaccines between birth and age five.

Merck, the sole producer of MMR, attributes its shortage to two voluntary interruptions to the production line. In a written statement, Merck apologized for the situation and said it is working hard to return to normal supply levels, which it expects over the next several months.

The initial MMR vaccine is given to children between their 12th and 15th months, and a booster shot is given at age five.

The booster is normally required before entry into school, and doctors and parents have expressed concern that the shortage may mean some children will not get their booster in time. Gellin says there is nothing magic about getting children vaccinated by a particular age, but laws are in place to ensure everyone gets vaccine protection.

"If indeed the law says 'no shot, no school,' then someone has to deal with that," said Gellin, "or are you going to keep a kid out of summer camp or school because Merck couldn't make the vaccine? Exceptions may have to be made."

The Advisory Committee on Immunization Practices took such steps in December when it voted to temporarily revise recommendations for Prevnar and the DTaP vaccine. It asked that Prevnar be made available first to children who are at high risk because of pre-existing medical conditions or day-care attendance, and recommended that the fifth dose of the DTaP vaccine be deferred.

"The interim recommendations are in place until enough supply is available," said Gellin. "The challenge is making sure the doctors on the front lines are aware of the change. Getting people to change the standard of care is a problem."

There are a number of reasons a drug or vaccine may be in short supply. For instance, DTaP is in short supply because one drug maker stopped producing tetanus toxoid-containing products and another drugmaker stopped making the vaccine altogether, leaving just two producers.

Merck, which also is the sole producer of the chickenpox vaccine, blamed the MMA and chickenpox shortages in part on modifications to the production line -- one suggested by the FDA and another that took longer than expected.

Wyeth-Ayerst's Prevnar vaccine, which was licensed last year, is in short supply because demand exceeded the manufacturer's projections.

A different problem is plaguing Merck's syringe-packaged vaccine for hepatitis A, a liver disease that's spread through contaminated food and water.

Suppliers were notified late last year that a number of lot numbers had low antigen levels. While people can be protected against hepatitis A even with low antigen levels, the company is recommending people be tested for immunity and consider revacination.

This vaccine recall is international and could affect thousands of people around the world.