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NEWS FROM THE VACCINE WORLD
Rotavirus
vaccine: Is it worth doing?
Preliminary recommendations discussed
by the ACIP suggest three doses at 2, 4 and 6 months of
age.
In
anticipation of possible FDA licensure of a pentavalent
human-bovine reassortant rotavirus vaccine (PRV, Rotateq,
Merck), the Advisory Committee on Immunization Practices
(ACIP) entertained preliminary immunization
recommendations at its recent meeting.
Rotavirus
 The
ACIP working group charged with formulating the
recommendations suggested routine immunization of
infants with three doses at 2 months, 4 months and 6
months of age. Dose one is best administered between 6
weeks and 12 weeks, Umesh D. Parashar, medical
epidemiologist at CDC, said.
"In an ideal
world, our plan is to have a set of recommendations that
could go forward as soon as the vaccine is licensed, and
we expect this will be in the February meeting," said
ACIP member John J. Treanor, MD, professor of medicine
in the infectious disease division of the University of
Rochester School of Medicine and Dentistry in New York.
Merck’s
investigational vaccine is an oral, liquid vaccine that
contains reassortant human-bovine rotaviruses of the
five human serotypes that cause the most rotavirus
disease worldwide: G1, G2, G3, G4 and P1. Merck filed an
application for FDA approval of the vaccine on April 5,
2005. Parashar said a decision on the vaccine is
expected from FDA by early February 2006.
The vaccine is
expected to have approximately an 18-month shelf life in
the clinic or practice.
Draft recommendations
Parashar said
the suggested, limited age window for dose one of the
series is based on studies that show the 6- to 12-week
age group is less likely to have intussusception.
Researchers have not evaluated the first dose in a
substantial number of children 3 months and older, the
cohort for whom the risk of intussusception was greatest
with the last rotavirus vaccine, Rotashield (Wyeth).
"The group felt
that this was an important concentration and since the
vaccine has not been evaluated in older infants, we
should limit the vaccine to the age group where more
data are available," Parashar said.
More generally,
the working group suggests the vaccine for children
whether or not they are breast-fed and children who have
mild, transient illness. The vaccine will be able to be
concomitantly administered with other vaccines in the
routine childhood immunization schedule.
Premature
infants younger than 37 weeks gestation are at risk for
severe disease, Parashar said, and the working group
suggested that these infants, when at least 6 weeks of
age and clinically stable, receive the vaccine.
It is still
suggested that infants who live with immunocompromised
people be vaccinated, because the risk of transmitting
the vaccine virus to household members is small.
If an infant
regurgitates the vaccine, the working group does not
recommend that ACIP repeat the dose, according to
Parashar.
One of the
issues to tackle before recommendations are made is
whether the infants should be discharged from the
hospital before receiving the vaccine.
Vaccine
precautions include preexisting gastrointestinal
disease, history of intussusception, moderate to severe
febrile illness and moderate to severe gastroenteritis.
Contraindications include allergy to vaccine components
and altered immune competence of the vaccine recipient.
(Infectious
Diseases in Children, December 2005)
Rotavirus Vaccines Are Coming Soon
Rotavirus
disease kills nearly half a million children annually
in developing countries, and it is a leading cause of
hospitalization among infants and children in the U.S.
In 1999, the first licensed rotavirus vaccine was
withdrawn from the market because it was associated with
intussusception (estimated rate, 1/10,000 recipients).
Now, results are available from two industry-supported,
randomized, placebo-controlled clinical trials of new
rotavirus vaccines.
Rotarix ,
a monovalent vaccine derived from the most common
rotavirus strain, was tested in 63,225 infants in Latin
America and Finland. Compared with placebo, two active
oral doses given at ages 2 months and 4 months reduced
severe rotavirus gastroenteritis and
rotavirus-associated hospitalization by 85%. Numbers of
intussusception cases within 100 days after the first
dose were similar in the two groups (9 in the vaccine
group and 16 in the placebo group).
Rotateq ,
a pentavalent human-bovine reassortant vaccine, was
tested in 68,038 infants in the U.S., Europe, Latin
America, and Taiwan. Compared with placebo, three active
oral doses, given 4 to 10 weeks apart, beginning between
6 and 12 weeks after birth, were highly efficacious,
reducing rotavirus-associated gastroenteritis and
hospitalization or emergency department visits by 95% at
14 or more days after the third dose. Efficacy against
rotavirus-associated gastroenteritis covered by the
vaccine (through the first full rotavirus season after
vaccination) was 74%. Again, rates of intussusception
were similar in the vaccine and placebo groups.
Comments:
These results are enormously gratifying. Rotavirus
vaccines could substantially reduce childhood mortality
in developing countries and health care use in the U.S.
However, editorialists caution that we don’t know how
effective the vaccines will be in the poorest countries
where other factors, such as malnutrition, affect
efficacy, or whether other rotavirus serotypes will
affect success. Further, is sufficient political and
economic support obtainable to make these vaccines
available in countries where they are most needed? Only
time will tell. Both vaccines await FDA approval.
— Howard
Bauchner, MD
Published in
Journal Watch Pediatrics and Adolescent Medicine
January 27, 2006
Effect of Single
Dose of SA 14-14-2 Vaccine 1 Year
After
Immunisation in Nepalese Children with Japanese
Encephalitis
Background
In July, 1999, a single dose of
live-attenuated SA 14-14-2 Japanese encephalitis vaccine
was given to children aged 1–15 years in the Terai
region of Nepal. Cases of natural infection occurred
almost immediately. Our aim was to assess the long-term
protective effect of this vaccination.
Methods
In 2000, this same population had a
second seasonal exposure to the virus. We therefore did
a case-control study to measure the prevalence of
vaccination against Japanese encephalitis in 35 patients
hospitalised for the disease 1 year after immunisation,
and in age-sex matched village controls.
Findings
Of 35 children resident in Bardiya
and Banke districts admitted to the Bheri Zonal Hospital
with serologically confirmed Japanese encephalitis, only
one had been vaccinated in 1999. In 430 age-sex matched
village controls, 234 (54·4%) were vaccinated. We
calculated a median unbiased estimate of the odds ratio
of 0·0155, with lower and upper confidence limits of
0·0004 and 0·0986. The protective effect of vaccine
after 12–15 months was 98·5% (CI 90·1–99·2%).
Interpretation
Our study provides evidence of
sustained high protection afforded by one dose of live
attenuated SA 14-14-2 vaccine in Nepalese children. (The
Lancet 2005; 366:1375-1378)
A Combination and Varicella Vaccine
Given to 4- to 6-Year-Old Healthy Children
In the
United States, children receive primary doses of M-M-RII
(Merck & Co, Inc, West Point, PA) and Varivax (Merck &
Co, Inc) beginning at 12 months, often at the same
health care visit. Currently a second dose of M-M-RII is
given to 4- to 6-year-old children, to increase
vaccination rates and to reduce the number of
individuals without detectable antibodies. A second dose
of a varicella-containing vaccine may result in similar
benefits.
OBJECTIVES.
To demonstrate that ProQuad (measles, mumps, rubella,
and varicella virus vaccine live; Merck & Co, Inc) may
be given in place of a second dose of M-M-RII or second
doses of M-M-RII and Varivax for 4- to 6-year-old
children.
METHODS.
Four- to 6-year-old children who had been immunized
previously with M-M-RII and Varivax were assigned
randomly to receive either ProQuad and placebo (N =
399), M-M-RII and placebo (N = 195), or M-M-RII and
Varivax (N = 205) and were then monitored for safety and
immunogenicity.
RESULTS.
ProQuad was generally well tolerated. Similarity (noninferiority)
was demonstrated in postvaccination antibody responses
to measles, mumps, and rubella between recipients of
ProQuad and all recipients of M-M-RII and in responses
to varicella between recipients of ProQuad and
recipients of Varivax. Postvaccination seropositivity
rates for antibodies against all 4 viruses were nearly
100% in all 3 groups. Small fold increases were observed
for measles, mumps, and rubella antibody titers. In
contrast, substantial boosts in varicella antibody
titers were observed among recipients of a second dose
of varicella vaccine, administered as ProQuad or Varivax.
CONCLUSIONS.
ProQuad may be used in place of a second dose of M-M-RII
or second doses of M-M-RII and Varivax for 4- to
6-year-old children. (Pediatrics 117(February 2006):
265-272.)
Effect of Combined Pneumococcal
Conjugate and Polysaccharide Vaccination on Recurrent
Otitis Media With Effusion
BACKGROUND .
Otitis media with effusion (OME) is very common during
childhood. Because Streptococcus pneumoniae is one of
the most common bacterial pathogens involved in OME,
pneumococcal vaccines may have a role in the prevention
of recurrent OME.
OBJECTIVE.
We sought to assess the effect of combined pneumococcal
conjugate and polysaccharide vaccinations on the
recurrence of OME.
METHODS.
A randomized, controlled trial was performed with 161
children, 2 to 8 years of age, with documented
persistent bilateral OME. All subjects were treated with
tympanostomy tubes (TTs). One half of the subjects were
assigned randomly to additional vaccination with a
7-valent pneumococcal conjugate vaccine 3 to 4 weeks
before and a 23-valent pneumococcal polysaccharide
vaccine 3 months after tube insertion. Blood samples
were drawn at the first vaccination, at the time of TT
placement, and 1 and 3 months after the second
vaccination. Levels of IgA and IgG serum antibody
against the 7-valent pneumococcal conjugate vaccine
serotypes 4, 6B, 9V, 14, 18C, 19F, and 23F were measured
with enzyme-linked immunosorbent assays. All children
were monitored for recurrence of OME for 6 months after
spontaneous extrusion of the TTs.
RESULTS.
The overall recurrence rate of bilateral OME was 50%.
Pneumococcal vaccinations induced significant 4.6- to
24.4-fold increases in the geometric means of all
conjugate vaccine serotype antibody titers but did not
affect recurrence of OME.
CONCLUSIONS.
Combined pneumococcal conjugate and polysaccharide
vaccination does not prevent recurrence of OME among
children 2 to 8 years of age previously known to have
persistent OME. Therefore, pneumococcal vaccines are not
indicated for the treatment of children suffering from
recurrent OME. (Niels van Heerbeek, Masja Straetemans,et
al. Pediatrics, March 2006, 117: 603-608.)
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