WHO study suggests low incidence of Hib in india is due to natural immunity

Indian J Med Res 2009;129: 205-207

Neeraj Gupta & Jacob Puliyel

We congratulate the authors of this meticulous study1.
The authors found the incidence of Hib meningitis only
0.007 per cent and they speculate that the population may
have ‘natural immunity’ to invasive Hib disease.
This paper is published 10 years after the data
were obtained. Three years ago an editorial published
in the ‘Expert Review Pharmacoeconomics Outcomes
Research’, cited this study as an instance of selective
non-publication of research2. To understand the
interest in this paper it is useful to remember the
context in which the study was done. Hib disease in
Asia is very low – six in 100,000 compared with 109
in 100,000 in the Western Pacific3. The thrust of Hib
research in Asia is to convince health planners that
Hib was a major problem that had gone unrecognized
due to poor microbiologic facilities and the technical
inability to culture the organism. An Invasive Bacterial
Infections Surveillance Group (IBIS) study performed
over 4 years, in six large referral hospitals in India,
employed sophisticated culture techniques to isolate
the organism4. This study also revealed a remarkably
low incidence of Hib disease4,5. Not convinced, the
World Health Organization (WHO) undertook this
large population-based study in Tamil Nadu, assuming
that hospital-based study like the IBIS study would
miss cases of meningitis that die in the community,
before they reach the hospital. The very low incidence
in this community based study, is therefore of great
interest to epidemiologists and health planners.
Unfortunately, because of this delay in
publication, the data could not inform the debate
prior to decision of the WHO to recommend Hib
vaccine to all infants. We have previously suggested
that ‘natural immunity’ (due to infections with
bacteria with cross-reacting antigens) was the
WHO study suggests low incidence of Hib in india is due to natural immunity
reason for the low incidence of invasive Hib disease
in India, and the reason why this population does not
need vaccination with Hib6. It is gratifying that this
is now borne out in a study supported by the WHO.
We hope the government and public health planners
will take note of this latest evidence against the need
for Hib vaccine in India.
Neeraj Gupta & Jacob Puliyel
Department of Pediatrics
St. Stephens Hospital
Delhi 110 054, India
1. Minz S, Balraj V, Lalitha MK, Murali N, Cherian T,
Manoharan G, et al. Incidence of Haemophilus influenzae
type b meningitis in India. Indian J Med Res 2008; 128 : 57-
2. Arora R, Puliyel JM. Economic evaluation tailored to
promote vaccine uptake: how third world consumers can
respond. Expert Rev Pharmacoeconomics Outcomes Res
2005; 5 : 515-6.
3. Levine OS, Schwartz B, Pierce N, Kane M. Development,
evaluation and implementation of Haemophilus influenzae
type b vaccines for young children in developing countries:
current status and priority actions. Pediatr Infect Dis J 1998;
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4. Invasive Bacterial Infections Surveillance (IBIS) Group
of the International Clinical Epidemiology Network. Are
Haemophilus influenzae infections a significant problem in
India? A prospective study and review. Clin Infect Dis 2002;
34 : 949-57.
5. Watt JP, Levine O, Santosham M. Global reduction of Hib
disease: what are the next steps? Proceedings of the meeting
Scottsdale, Arizona, September 22–25, 2002. J Pediatr
2003; 143 (6 Suppl) : S163-87.
6. Puliyel JM, Agarwal KS, Abass FA. Natural immunity
to Haemophilus influenzae in infancy in Indian children.
Vaccine 2001; 19 : 4592-4.