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Indian Pediatr 2016;53: 356 |
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Clippings
Theme: Immunization
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Vipin M Vashishtha
[email protected]
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Epidemiological and economic effects of priming with the whole-cell pertussis vaccine
(JAMA Pediatr.2016 Mar 28. doi: 10.1001/jamapediatrics.2016.0047)
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Current acellular pertussis vaccines may not protect against
transmission of Bordetella pertussis. This simulation study was
conducted (June 2014 to May 2015) to assess whether a priming dose of
whole-cell pertussis (wP) vaccine is cost-effective at reducing
pertussis infection in infants. The population was divided into 9 age
groups corresponding to the current pertussis vaccination schedule, and
fit to 2012 pertussis incidence. A priming dose of wP vaccine into the
current acellular pertussis vaccination schedule was included. The
results of the study reveal that switching to a wP-priming vaccination
strategy could reduce whooping cough incidence by up to 95%, including
96% fewer infections in neonates. Although there may be an increase in
the number of vaccine adverse effects, nonetheless a 95% reduction in
quality-adjusted life-years lost with a switch to the combined strategy
and a cost reduction of 94% was estimated, saving more than $142 million
annually. The results suggest that an alternative vaccination schedule
including 1 dose of wP vaccine may be highly cost-effective and
ethically preferred until next-generation pertussis vaccines become
available.
Comment: More and more studies are now
highlighting the inferior protection against pertussis accorded by
acellular pertussis than whole cell vaccines. However, as far as
industrialized countries are concerned, reverting back to wP vaccines is
fraught with the danger of disruption of their well-established mass
immunization program against pertussis, owing mainly to negative public
opinion toward the wP vaccine.
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Reciprocal interference of maternal and infant
immunization in protection against pertussis (Vaccine.
2016;34:1062-9)
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Because of the current re-emergence of pertussis, vaccination during the
3rd trimester of pregnancy is recommended in several countries in order
to protect neonates by placental transfer of maternal antibodies. In
this study, the potential reciprocal interference of mother and infant
vaccination in protection against pertussis in mice was examined. Female
mice were vaccinated with acellular pertussis (aP) vaccines and
protection against Bordetella pertussis challenge, as well as
functional antibodies were measured in their offspring with or without
re-vaccination. Maternal immunization protected the offspring against
B. pertussis challenge, but protection waned quickly and was lost
after vaccination of the infant mice with the same vaccine. Without
affecting antibody titers, infant vaccination reduced the protective
functions of maternally-derived antibodies, evidenced both in vitro
and in vivo. Protection induced by infant vaccination was also
affected by maternal antibodies. However, when mothers and infants were
immunized with two different vaccines, no interference of infant
vaccination on the protective effects of maternal antibodies was noted.
The researchers concluded that it may be important to determine the
functionality of antibodies to evaluate potential interference of
maternal and infant vaccination in protection against pertussis.
Comment: This study added yet another
dimension to the interaction between maternal antibodies and primary
infant pertussis vaccination in which not only maternal antibodies
‘blunt’ the immune responses of infant’s primary vaccination, but
antibodies generated by infant vaccination also impair the functionality
of maternal antibodies. Indirectly, the study favors the use of wP
vaccine as primary infant pertussis vaccination since wP-based vaccines
cannot be administered to pregnant mother.
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Live attenuated influenza vaccine may be less
effective against A(H1N1) than inactivated influenza vaccine
(Pediatrics. 2016;137:1-10)
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Few observational studies have evaluated the relative effectiveness of
live attenuated (LAIV) and inactivated (IIV) influenza vaccines against
medically-attended laboratory-confirmed influenza. The researchers at
CDC, Atlanta, analyzed US Influenza Vaccine Effectiveness Network data
from participants aged 2 to 17 years during 4 seasons (2010–2011 through
2013–2014) to compare relative effectiveness of LAIV and IIV against
influenza-associated illness. Vaccine receipt was confirmed via
provider/electronic medical records or immunization registry. The odds
ratio of influenza-positive to influenza-negative was calculated among
those age-appropriately vaccinated participants with either LAIV or IIV
for the corresponding season. Of 6819 participants, 2703 were
age-appropriately vaccinated with LAIV (n=637) or IIV (n=2066).
Odds of influenza were similar for LAIV and IIV recipients during 3
seasons (2010–2011 through 2012–2013). In 2013–2014, odds of influenza
were significantly higher among LAIV recipients compared with IIV
recipients 2 to 8 years old (OR 5.36; 95% CI, 2.37 to 12.13).
Participants vaccinated with LAIV or IIV had similar odds of illness
associated with influenza A/H3N2 or B. LAIV recipients had greater odds
of illness due to influenza A/H1N1pdm09 in 2010–2011 and 2013–2014. The
researchers observed lower effectiveness of LAIV compared with IIV
against influenza A/H1N1pdm09 but not A(H3N2) or B among children and
adolescents, suggesting poor performance related to the LAIV A/H1N1pdm09
viral construct.
Comment: Till recently, LAIV was considered superior to IIV as
far as protective efficacy against influenza among healthy individuals
is concerned. The results of this study are quite relevant to us since
majority of seasonal influenza in India is caused by A/H1N1pdm09
serotype.
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