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U.S. Food and
Drug Administration
FDA Consumer magazine
September-October 2002
Table
of Contents
by Michelle Meadows
Judi Chase says she's not winning any popularity contests these days. As a program manager for vaccines at the Texas State Department of Health, she's used to fielding questions from health-care providers who want to know why their vaccines are late and what she's going to do about it. Her department coordinates the vaccine supply for about 3,000 providers in the state's Vaccines for Children program. "I try to tell them it's not us," Chase says.
She also understands the providers' frustration. "It's hard enough to get people vaccinated the first time," she says. "So if they're told the supply is out, it's especially difficult to get them back." The biggest supply challenges for Texas over the past year have been with the chickenpox vaccine and with the pneumococcal vaccine, Prevnar. And while the chickenpox vaccine supply is returning to normal, Prevnar remains a problem. "We need about 80,000 doses of Prevnar a month, and we get about 15,000 doses a month from the manufacturer," Chase says. One strategy has been to take the available doses and divide them up so that various providers each can have a small percentage. "But then when it's gone, it's gone," she says.
When it's gone, doctors have to track patients and tell them to come back when the supply is back up. In critical situations, they send patients to other providers. Dianna Heyer, R.N., nursing service coordinator at the Macon County Department of Health in Decatur, Ill., says doctors in her area who don't have tetanus and diphtheria (Td) vaccine have referred patients with wounds to the county clinic. The vaccine prevents a neurological disease known as lockjaw and a life-threatening respiratory illness.
"We've been able to give the shot to people with wounds," Heyer says, "but we couldn't give routine Td boosters for the last year." For example, Heyer's clinic couldn't give boosters to children in ninth grade last year. As a result of recent vaccine shortages, which have mostly affected childhood vaccines, several states temporarily suspended school entrance requirements for immunizations.
Td boosters are normally given at age 11 or 12 with a subsequent booster given every 10 years, according to the vaccine schedule recommended by the Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices (ACIP). Now that the Td supply is back to normal everywhere, Heyer says they will probably hold special clinics this year so the children who missed shots last year can catch up.
There are many reasons for the shortages. A major reason is the fact that there are relatively few manufacturers in the vaccine business. It's also difficult to make vaccines; from start to finish, a particular batch of a given vaccine requires roughly a year of production time. Unlike most drugs, vaccines are produced from living cells and organisms. Most require growing the immunizing agent, whether it's bacteria or viruses, in a production facility where growth conditions are complex.
William Egan, Ph.D., deputy director of the FDA's Office of Vaccine Research and Review, says, "No disease outbreaks have resulted from the shortages, but children not being fully immunized is always a concern." Fortunately, projections by manufacturers indicate that serious shortages of several vaccines are easing. Here's an update on vaccines that have been in short supply:
Diphtheria and Tetanus Toxoids and Acellular Pertussis (DTaP): Calling it a business decision, Wyeth Lederle of Pearl River, N.Y., stopped making DTaP in 2001. This left only two manufacturers of the vaccine, Aventis Pasteur of Swiftwater, Pa., maker of Tripedia, and GlaxoSmithKline of Philadelphia, Pa., maker of Infanrix.
In addition, Aventis Pasteur made changes to remove a mercury-containing preservative called thimerosal from DTaP and had to go through FDA clearance. The company made the change by switching from multi-dose to single-dose packaging. And this uses a greater amount of vaccine per dose to make sure the full dose can be drawn from a vial. Glaxo's DTaP product was already thimerosal-free.
During the shortage, ACIP recommended that if providers didn't have enough DTaP to vaccinate all children with the standard five doses, they should make it a priority to vaccinate infants with the first three doses. Normally, children receive one dose each at ages 2 months, 4 months, and 6 months, followed by another dose at age 15-18 months and the final dose at age 4 to 6.
The DTaP supply has returned to normal, in part, because the FDA licensed a new DTaP vaccine (DAPTACEL) by Aventis Pasteur in May 2002. DAPTACEL is indicated for immunizing children ages 6 weeks to 6 years.
Measles, Mumps, Rubella (MMR): According to Merck & Company, West Point, Pa., temporary shortages of some vaccines they produce, including the MMR vaccine (M-M-R II), are due to two voluntary interruptions in their manufacturing operations. Merck voluntarily closed one facility after the FDA raised issues during a routine inspection. Another facility closing was already scheduled and took longer than expected.
During the shortage, ACIP recommended administration of the first dose in the 2-dose MMR regimen at age 12-15 months and deferral of the second dose that's recommended at 4-6 years. The supply is now back to normal.
Chickenpox (Varicella): Merck's manufacturing shutdowns also affected production of the chickenpox vaccine, VARIVAX. ACIP recommended that during the shortage, vaccine providers should delay vaccination of children until the age of 18 months or 2 years. Normally, the recommendation is one dose of varicella vaccine between 12 months and 18 months or at any age after 18 months if a child has not had chickenpox or the vaccine.
Vaccination was recommended for susceptible children ages 5 to12, especially those entering school, and adolescents age 11 or 12. People not vaccinated until age 13 or older should get two doses, four to eight weeks apart. This shortage is likely to improve soon, but it will still take time to build up the inventory of chickenpox vaccine.
Pneumococcal Conjugate: Wyeth Vaccines markets Prevnar, approved by the FDA in 2000 to prevent invasive pneumococcal diseases in infants and toddlers. A shortage has occurred because demand was unexpectedly high, exceeding supply. Infants normally receive a series of four shots, the first three given at two-month intervals beginning at 2 months and ending at 6 months, with the final shot in the series given at 12-15 months of age. During the shortage, ACIP temporarily changed recommendations so that infants receive the first three doses and will get the fourth dose when the supplies are sufficient. According to manufacturer projections, pneumococcal conjugate vaccine will remain in short supply through 2003.
Tetanus and Diphtheria Toxoids for adults (Td): Along with DTaP, the Td supply was affected when Wyeth Lederle decided to stop producing tetanus and diphtheria toxoids in 2001. In this case, only one major producer--Aventis Pasteur--remained. Production of the vaccine, from start to finish, takes about a year.
ACIP had recommended that routine Td boosters for adolescents and adults temporarily be deferred and that people return for shots once the supply was sufficient. Compared with distribution levels before the shortage, the amount of Td distributed nationally dropped 40 percent during 2001-2002. Now, the supply of adult Td in the United States has reached levels high enough that the routine Td schedule as recommended by ACIP can be resumed.
Prioritizing patients and adjusting the routine schedule of immunizations is clearly a short-term solution. Federal agencies, meantime, have been meeting to address long-term strategies to head off future shortages.
The FDA's Egan says some of the possible solutions being discussed include requiring manufacturers to give sufficient notice before interrupting or ending vaccine production so that other manufacturers can increase production. "We're also looking at what we can do at FDA to speed up lot release to get vaccines on the market sooner," he says.
Experts also are talking about ways to boost the vaccine stockpile. This isn't a big warehouse of extra vaccine, but rather refers to the CDC's Storage and Rotation Contracts with manufacturers. The contracts allow the CDC to buy vaccine beyond the national need so there is a supply to draw from in an emergency.
The CDC has the authority to stockpile six-month supplies of vaccines. It has been drawn on several times. Manufacturers borrow from the stockpile and usually replace it within a year. The CDC sets priorities for vaccine stockpiles, which typically contain vaccines that are routinely recommended and that have a single manufacturer. The MMR vaccine, for example, has been stockpiled since 1983.
Because of distribution delays with the flu vaccine over the last couple of years, the CDC's Advisory Committee on Immunization Practices (ACIP) is recommending that certain groups get their flu shots in October and earlier this year in anticipation of the 2002-2003 flu season.
The groups include people at high risk for complications from the flu (such as those age 65 and up and people of any age with certain chronic health conditions) and health-care workers. Children younger than 9 receiving the vaccine for the first time need a booster dose one month after the initial dose.
Everyone else should begin flu vaccination in November. The optimal months for vaccination are October and November, but ACIP encourages the use of vaccines even later than November because it's still likely to be beneficial. The number of influenza cases in the United States typically has not peaked until late December through early March.
ACIP also is encouraging flu vaccination for healthy children ages 6 months to 23 months and for those who come into close contact with children up to 23 months because of the increased risk for influenza-related hospitalizations in this age group. A full recommendation for this age group is expected in the next few years.
Making sufficient supplies of flu vaccine is always a challenge because the predominant flu strains change every year. A drop in the number of flu vaccine manufacturers and the slow growth rate of certain strains of the influenza virus have created temporary shortages in the past.
The FDA works closely with companies to determine whether the supply will be adequate. Early last year, the FDA contacted the three influenza vaccine manufacturers--Aventis Pasteur, Evans Vaccines Ltd., and Wyeth--to discuss projections. Production problems limited the number of doses available early in the flu season, but as a result of the meetings, manufacturers produced the largest number of doses ever in a given year during 2001-2002 (about 87 million doses).
The latest manufacturer projections indicate that ample flu vaccine is expected for 2002-2003.
For a complete list of who should get a flu shot, visit www.cdc.gov/ncidod/diseases/flu/who.htm.
--M.M.
Check with your health-care provider about whether you need the following vaccines:
To access the complete recommended schedule of adult vaccines, including information on warnings and specific high-risk groups, contact www.cdc.gov/nip/recs/adult-schedule.htm.
Source: Centers for Disease Control and Prevention