Study Supports Reduced Dose Regimen For Wyeth's Prevnar
July 07 2009 - 4:30PM
Dow Jones News
A new study supports the notion that giving Wyeth's (WYE)
childhood vaccine Prevnar in fewer doses than some standard
regimens is sufficient to protect against a bug that causes
meningitis and pneumonia.
The finding could hurt sales of the best-selling vaccine in the
world if more national governments opt for fewer doses in their
immunization programs. But officials from Wyeth and the U.S.
Centers for Disease Control signaled that was unlikely to happen in
the U.S. anytime soon.
Prevnar has been credited with substantially reducing rates of
so-called pneumococcal infections since its launch in 2000. Wyeth
of Madison, N.J., sold more than 47 million doses of Prevnar
worldwide in 2008, generating $2.7 billion in sales, 11% higher
than the year before. It costs about $83 per dose in the private
market in the U.S. The vaccine stands to be one of the prizes New
York-based Pfizer Inc. (PFE) inherits when it closes its planned
acquisition of Wyeth, expected later this year.
The 1,000-child study, financed by the Dutch Ministry of Health
and conducted in the Netherlands, concluded that giving Prevnar to
infants in two initial doses, followed by a booster shot, reduced
the rates of carriage of the targeted bacteria in vaccinated
children in the second year of life by about 60%, versus
unvaccinated children.
Currently, Prevnar is given in three initial doses followed by a
booster shot - known as 3-plus-1 - in the U.S., Germany, the
Netherlands and elsewhere. However, other countries including the
U.K., Sweden and Norway, already offer the vaccine as two initial
doses plus a booster shot, or 2-plus-1, in their national
immunization programs. The reduced-dose regimen matches the
schedule for other childhood shots in those countries and has the
added bonus of saving money.
"In my opinion you could safely go to two-plus-one," said
Elisabeth Sanders, one of the study's co-authors and professor of
pediatric immunology and infectious diseases at University Medical
Center Utrecht in the Netherlands. "Why not save the one injection
if it's not required?"
The study's results were published online Tuesday by the medical
journal JAMA.
Although the new study didn't directly compare the 2-plus-1
regimen with 3-plus-1, Sanders said the reduced rate of bacteria
carriage was comparable to that seen in other studies of the
3-plus-1 regimen.
Sanders said the reduced-dose regimen might be useful in
developing countries, where resource constraints and logistics
problems make it difficult to implement a 3-plus-1 schedule.
Emilio Emini, Wyeth's executive vice president of vaccine
research and development, said the 2-plus-1 schedule can be
effective, but he didn't expect any significant changes in dosing
schedules in national immunization programs.
The U.S. schedule of "3-plus-1" has the benefit of rapidly
building up immunity in infants, Emini said. He said he expects the
Prevnar schedule to stay the same in the U.S. because it matches
the schedules for other childhood vaccines.
The success of Prevnar in battling disease has stemmed not only
from the direct protection provided to individuals but also in
building up "herd immunity," in which unvaccinated or partially
vaccinated people get protection because the targeted bugs don't
circulate as widely as before the vaccine was introduced. Emini
said the 2-plus-1 schedule relies more heavily on herd immunity to
provide protection.
The U.S. CDC currently recommends infants receive Prevnar shots
at two, four and six months, plus a booster shot between 12 and 15
months. Earlier this decade, the CDC temporarily recommended fewer
doses due to supply shortages at Wyeth.
Matthew Moore, a medical epidemiologist with the CDC, said
"we've had terrific success in this country with the existing
schedule we have." The CDC estimates Prevnar has helped prevent
more than 200,000 cases of pneumococcal disease since its
launch.
The Dutch study also found that giving Prevnar in two doses only
- with no booster shot - reduced carriage rates of the targeted
bugs at two years by an amount similar to the 2-plus-1 schedule.
But Sanders didn't recommend that countries adopt a two-dose-only
regimen because it probably wouldn't offer long-term protection.
Emini said such an approach would erode herd immunity over
time.
Wyeth has developed a new vaccine designed to provide broader
protection against pneumococcal disease, Prevnar-13, and is
awaiting U.S. and European regulatory action. GlaxoSmithKline PLC
(GSK) recently gained approval to sell a rival vaccine, Synflorix,
in Europe.
-Peter Loftus; Dow Jones Newswires; 215-656-8289;
peter.loftus@dowjones.com