|
-
What is the ideal age
for H. influenzae vaccination? Although the manufacturers
recommend starting at 2 months of age, the information available in
the journal is not very clear on this issue(1,2). Moreover, many
practitioners and even some government hospitals are routinely
giving the vaccine at 6 weeks of age (1 dose). Further, what is the
ideal/recommended interval between the three doses of this vaccine
during the primary schedule? I have noted many children who have
received the first three doses at 1 month intervals along with the
DPT vaccine. The manufacturers and various authorities in this field
recommend a minimum interval of two months between the doses in the
primary schedule. If the ideal age for Hib vaccine is 2 months, is
it justifiable to delay DPT vaccination to 2 months of age?
-
Can measles vaccine
be given intra-muscularly? Many centers have been using this route
for measles vaccine routinely.
-
Varicella vaccine is
known to cause a few (less than 50 usually) varicella like eruptions
in around 4% of the vaccines. Does this also mean that the vaccine
virus can get reactivated in later life and can cause Herpes
zoster?
-
What is the duration
of protection with varicella vaccine and is there a need for
booster?
Devendra Mishra,
163, Sahyog Apartments,
Mayur Vihar, Phase I,
Delhi 110 091, India.
-
John TJ. Hemophilus
influenzae type b vaccine. Indian Pediatr 1998; 35: 71-72.
-
John TJ.
Transplacental transfer of H. influenzae type b antibody.
Indian Pediatr 1998; 35: 919-920.
-
The protein
conjugated Hib vaccines are immunogenic in young infants. Most
studies have used the schedule of a dose each at 2, 4 and 6 months,
according to the DPT schedule in the USA, and the immune responses
have been very good. Therefore, it is quite reasonable to expect
good antibody response even if the first dose is started at 6 weeks
and the interval between doses is reduced to 4 weeks, to fit with
the current schedule of DPT in India. Indeed there have been some
studies confirming this. By 6 weeks, the maternal antibody level,
low to begin with, would have declined markedly. Since the problem
of invasive Hib disease begins by about 2-3 months and peaks around
6 to 12 months, it is very important to start the immunization
schedule early than late. On the other hand, there is no longer any
such hurry for DPT vaccines, particularly since pertussis, the main
target for early start of DPT, is no longer rampant as it used to be
in the pre-EPI days.
-
Measles, MMR and
Varicella vaccines are recommended to be given subcutaneously. We
had conducted some studies, first in monkeys and later in children,
giving measles vaccine intramuscularly, either by itself or along
with DPT or DPT-Polio vaccines and the antibody responses to the
measles virus have been as good as when it was given
subcutaneously(1,2). So, the intramuscular route is acceptable, but
the recommended route continues to be subcutaneous.
-
Varicella vaccine
does not usually cause any rash, but occasionally it can cause a
maculopapular or even vesicular rash, but with very few vesicles. It
appears that abundant skin vesicles are the source of seeding the
virus into the posterior nerve root ganglia, where it may remain for
many years to decades, and then spread peripherally along one nerve
and cause unidermatomal herpes zoster. Since varicella vaccine virus
is attenuated and also not usually associated with many vesicles,
the likelihood of later herpes zoster is also very low after
vaccination. In immunocompromised children herpes zoster has
occurred, with the recovery of the vaccine virus from the vesicles,
but in general, in normal children, varicella vaccine protects
against varicella and herpes zoster.
-
In Japan, varicella
vaccine had been in use for over 20 years and the protective
efficacy continues to be of the order of about 95%.
-
John TJ, Selvakumar
R. Mixing measles vaccine with DPT and DPTP. Lancet 1985; p 1154.
-
John TJ, Selvakumar
R, Simoes EAF, Balraj V. Antibody response to measles vaccine given
mixed with DPTP. Amer J Dis Child 1987; 141: 14-16.
T. Jacob John,
Emeritus Medical Scientist (ICMR),
439, Civil Supplies Godown Lane,
Kamalakshipuram,
Vellore TN 632 002,
India.
E-mail: [email protected]
|
