Pig Virus DNA Found in Rotavirus Vaccine

March 22, 2010 -- GlaxoSmithKline's Rotarix rotavirus vaccine contains DNA from an
apparently harmless pig virus, the company and the FDA today announced.
The FDA estimates that 1 million U.S. kids have received the Rotarix
vaccine.
The contamination was discovered by researchers developing a new technique
for detecting viral material. GlaxoSmithKline confirmed that the pig virus,
porcine circovirus type 1 or PCV-1, has been in the vaccine since it was
developed.
This means that pig virus DNA was in the vaccine throughout clinical trials.
No safety issues emerged from these international studies with 90,000
participants or, GlaxoSmithKline says, in post-marketing surveillance covering
more than 69 million doses of the vaccine.
Nevertheless, as a precaution the FDA is asking doctors to stop using the
two-dose Rotarix vaccine, which it approved in 2008.
"The message is clearly not a message of safety but of caution going
forward," FDA Commissioner Margaret Hamburg, MD, said at a news conference. "We
believe the vaccine is both safe and effective and we strongly encourage
vaccination against rotavirus. But we want to more deeply understand the
finding of this unexpected material in the product, and that is why we are
putting a clinical pause on its use."
 
Alternative Rotavirus Vaccine Available
About 75% of U.S. doctors prescribe the three-dose RotaTeq vaccine, made by Merck, which was approved in
2006.
Because rotavirus causes severe diarrheal disease in infants, rotavirus
vaccination begins at age 2 months. The FDA says children who already received
one dose of the Rotarix vaccine should follow up with two doses of the RotaTeq
vaccine. Those who already received two doses of Rotarix should be fully
protected.
Merck's RotaTeq vaccine is made using a different process and is not
contaminated with PCV-1.
It's not at all clear what it means to have found PCV-1 DNA in a vaccine.
It's not yet clear whether the vaccine contains only fragments of the pig virus
or whether the vaccine contains whole virus capable of replication.
PCV-1 does not cause disease in humans. It does not even appear to cause
disease in pigs. According to GlaxoSmithKline, it's a common virus that's often
eaten in meat products with no resulting illness.
To sort out these issues, the FDA is convening a panel of experts. The panel
is expected to meet in four to six weeks and will be charged with advising the
FDA on what to do next.
Meanwhile, GlaxoSmithKline is working to replace all contaminated Rotarix
seed virus and the cell banks in which it is grown. But in the meantime, the
company says in a news release, it will continue to manufacture the
vaccine.
While rotavirus disease can be serious in developed nations, in the
developing world it is a devastating diarrheal disease that each year kills a
half million children. Benefits of the vaccine in these nations far outweigh
its theoretical risks.
"While we investigate, we do have the luxury of an alternative product in
this country," Hamburg said. "So while we are proceeding with a more in-depth
investigation, clinicians in the U.S. should use the alternative product
instead."
The issues with Rotarix, in which no safety issues have been seen, are very
different from issues that arose with Wyeth's Rotashield vaccine. A year after
its approval in 1998, Rotashield was linked to an increased risk of a serious
bowel complication called intussusception. It was quickly taken off the
market.
Studies find that neither GlaxoSmithKline's Rotarix nor Merck's RotaTeq
rotavirus vaccines cause intussusception.
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