Like lead-painted Thomas the Tank Engine toys or ground beef contaminated with E. coli bacteria, the swine flu vaccine is now the subject of a mass recall.
Nearly 1 million H1N1 children’s shots that were part of Tuesday’s nationwide recall had diminished in potency but were still safe for use, the Centers for Disease Control and Prevention said.
On Wednesday, Sacramento health care providers scrambled to see if they had administered any of the recalled vaccine so they could notify parents – even though the parents won’t be asked to take any action in response.
Given the urgent calls from health officials in recent months to get children vaccinated, parents might be left wondering how so many shots could have been recalled.
Experts say anything being produced in the millions will have flukes. In the past decade, a handful of vaccines have been recalled because of problems with their effectiveness.
“It’s not unlike making a soufflé,” said Dr. Robert Schooley, chief of the division of infectious diseases at the UC San Diego School of Medicine. “Most come out right, and sometimes they don’t.”
Made by French pharmaceutical firm Sanofi Pasteur, the recalled H1N1 shots are single-dose, prefilled syringes for children ages 6 months to 35 months.
The shots met clinical standards when they were shipped in November, but subsequent testing showed four batches – 47,800 doses of which made their way to California – were about 12 percent below the threshold of recommended potency. The shots account for 9 percent of California’s total number of prefilled syringes for young children.
Children under age 10 are urged to get two doses of the vaccine spaced one month apart. Young children who received the recalled vaccine won’t need to get additional doses beyond those two, the CDC said.
Sanofi Pasteur would not elaborate on why the vaccine had lost some of its potency.
“At this time, we don’t have all the answers,” said spokesman Len Lavenda.
But experts said there could be multiple reasons for the degradation.
All flu shots are made by growing strains of the virus in eggs, then killing it, mixing dead virus particles with other ingredients and putting it all into bottles or syringes.
When injected, the dead virus particles stimulate the body’s immune response without sickening the patient, since the virus lacks all the pieces it needs to make a person sick. The next time the virus appears, the body “remembers” it and can destroy it.
Testing determines the concentration of dead virus needed to achieve an optimal immune system response, said Schooley, the UC San Diego professor.
“Sometimes the proteins unfold in a way that make them noneffective, or there is precipitation of them in clumps,” he said.
“These things happen with medications, and with vaccines you usually don’t hear about them. In this case everybody is worried about it because it’s a high-profile disease with a vaccine we wish we had more of.”
The problem with the recalled vaccine was that it degraded at a faster rate than expected, said Dr. Neal Halsey, director of the Institute for Vaccine Safety at Johns Hopkins Bloomberg School of Public Health.
“All vaccines have a certain time before expiration,” he said. “These four lots changed a little bit faster.”
Halsey said the recall is actually evidence that the government and vaccine manufacturers are acting responsibly and testing regularly.
Other recent vaccine recalls:
• In February, Novartis recalled five lots of seasonal flu vaccine in prefilled syringes.
• In December 2007, Merck recalled 1 million Hib vaccines used to protect against meningitis, because of sterility concerns.
Nearly 1 million H1N1 children’s shots that were part of Tuesday’s nationwide recall had diminished in potency but were still safe for use, the Centers for Disease Control and Prevention said.
On Wednesday, Sacramento health care providers scrambled to see if they had administered any of the recalled vaccine so they could notify parents – even though the parents won’t be asked to take any action in response.
Given the urgent calls from health officials in recent months to get children vaccinated, parents might be left wondering how so many shots could have been recalled.
Experts say anything being produced in the millions will have flukes. In the past decade, a handful of vaccines have been recalled because of problems with their effectiveness.
“It’s not unlike making a soufflé,” said Dr. Robert Schooley, chief of the division of infectious diseases at the UC San Diego School of Medicine. “Most come out right, and sometimes they don’t.”
Made by French pharmaceutical firm Sanofi Pasteur, the recalled H1N1 shots are single-dose, prefilled syringes for children ages 6 months to 35 months.
The shots met clinical standards when they were shipped in November, but subsequent testing showed four batches – 47,800 doses of which made their way to California – were about 12 percent below the threshold of recommended potency. The shots account for 9 percent of California’s total number of prefilled syringes for young children.
Children under age 10 are urged to get two doses of the vaccine spaced one month apart. Young children who received the recalled vaccine won’t need to get additional doses beyond those two, the CDC said.
Sanofi Pasteur would not elaborate on why the vaccine had lost some of its potency.
“At this time, we don’t have all the answers,” said spokesman Len Lavenda.
But experts said there could be multiple reasons for the degradation.
All flu shots are made by growing strains of the virus in eggs, then killing it, mixing dead virus particles with other ingredients and putting it all into bottles or syringes.
When injected, the dead virus particles stimulate the body’s immune response without sickening the patient, since the virus lacks all the pieces it needs to make a person sick. The next time the virus appears, the body “remembers” it and can destroy it.
Testing determines the concentration of dead virus needed to achieve an optimal immune system response, said Schooley, the UC San Diego professor.
“Sometimes the proteins unfold in a way that make them noneffective, or there is precipitation of them in clumps,” he said.
“These things happen with medications, and with vaccines you usually don’t hear about them. In this case everybody is worried about it because it’s a high-profile disease with a vaccine we wish we had more of.”
The problem with the recalled vaccine was that it degraded at a faster rate than expected, said Dr. Neal Halsey, director of the Institute for Vaccine Safety at Johns Hopkins Bloomberg School of Public Health.
“All vaccines have a certain time before expiration,” he said. “These four lots changed a little bit faster.”
Halsey said the recall is actually evidence that the government and vaccine manufacturers are acting responsibly and testing regularly.
Other recent vaccine recalls:
• In February, Novartis recalled five lots of seasonal flu vaccine in prefilled syringes.
• In December 2007, Merck recalled 1 million Hib vaccines used to protect against meningitis, because of sterility concerns.
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