|
Indian Pediatr 2012;49: 996 |
|
Reply
|
Vipin M Vashishtha
Convener, IAP Committee on Immunization, Mangla
Hospital& Research Center, Shakti Chowk,
Bijnor, Uttar Pradesh, 246701,India
Email: [email protected]
|
It is not feasible to discuss all the issues related to all
the available vaccines in a single meeting. Regarding your
suggestion on use of reduced quantity of whole cell
pertussis vaccines to adolescents and adults (through
DTP/DT/Td), we cannot recommend this until adequate trials
are conducted with proper protocol and after proper approval
and clearance from national regulatory authority (NRA).
Moreover, it is beyond the purview of IAPCOI to produce an
indigenous affordable Tdap/pertussis vaccine for the
adolescents.
IAPCOI has recommended two dose schedule
for prevention of ‘breakthrough varicella’ [1]. Following
are the rationale behind IAPCOI’s recommendations:
1. The recommended ages for routine
first (at age 12-15 months) and second (at age 4-6
years) doses of varicella vaccine are harmonized with
the recommendations for MMR vaccine use and intended to
limit the period when children have no varicella
antibody. The recommended age for the second dose is
supported by the current epidemiology of varicella, with
low incidence and few outbreaks among preschool-aged
children and higher incidence and more outbreaks among
elementary school-aged children.
2. Although, most studies are done
when 2nd dose is given after 3 months of the first,
there are few trials where the two schedules were
compared and it was concluded that among children, VZV
antibody levels and GMTs after 2 doses administered 4-6
years apart were comparable to those obtained when the 2
doses were administered 3 months apart (seroconversion:
99.2% vs 99.6%, GMTs: 212.4 vs 142.6,
respectively).
3. However, the CMI responses
measured by mean stimulation index (SI), a marker of
cell-mediated immunity were 36.9 for 2nd dose after 3
months of primary dose, and 58.6 when 2nd dose was given
at 4-6 yrs of age [2].
References
1. IAP Guidebook on Immunization,
2009-11. Eds. Yewale V, Choudhury P, Thacker N. Individual
vaccines; Varicella vaccine. Available from:
http://www.iapcoi. com/hp/pdf/IAP%20GUIDE%20BOOK%20ON%20
IMMUNIZATION%20INDIVIDUAL%20VACCINES.pdf. Accessed on
September 4, 2012.
2. MMWR, Recommendations and Reports. Prevention of
Varicella. Recommendations of the Advisory Committee on
Immunization Practices (ACIP). June 22, 2007/ 56(RR04);1-40.
Available from:
http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5604a1.htm.
|
|
|
|