Current Status in India
In 2009, a total of 124 cases of WPV and 4 compatible
cases have been notified till the week ending 11 July. Two VDPV cases are
to be added to this tally. Reminding ourselves of the 2004-08 GPEI
strategic plan, following milestones for 2007-2008 have not been
adequately achieved: (i) long-term immunization policies, including
national IPV decisions; (ii) introducing protocols for cVDPV
response; and (iii) beginning of environment sampling.
The disappointments of 2008 are thus well known. The
GPEI strategic plan begins on an optimistic note, planning to interrupt
all WPV1 transmission in India by 2009. With 27 WPV1 cases already
notified and the peak monsoon/post-monsoon period yet to set in, this
objective shall remain unrealized.
What are the Key Concerns?
VDPVs signify continuing low levels of immunity at the
population level. High routine immunization (RI) coverage is one of the
four basic tenets of this eradication strategy. Media reports suggested
that the child in Bihar received several doses of pulse polio but no dose
of RI. Despite impressive national/state/district aggregates, less visible
clusters of children with low RI may sustain the infection. 48% children
completed all doses of RI in Assam; the corresponding figure for East
Champaran District, Bihar was 41.3%.
The search for individual-level ‘risk factors’ (through
immunological and clinical status of both children), in the risk factor
epidemiology paradigm, should not obfuscate population-level determinants
of low RI coverage. That would be missing the wood for the trees. Public
health programs (vertical, time-bound) are often reduced to ‘technology
missions’. Repetitive activities (as in pulse polio rounds) lead to
fatigue and burnout of both providers and recipients/communities,
particularly in the absence of a functioning and responsive primary
healthcare system.
The Way Ahead
The VDPV cases in India emerged in the twenty-fifth
year of the history of ideas of polio eradication, first considered in
1983. There was broad-based scientific and political support when the
campaign was launched in 1994-95. Scripted as a short story (achieving
eradication in 2000) this is slowly but inexorably turning out to be a
saga. The GPEI is yet to visualize a scenario where vaccines are no longer
required; the hallmark of eradication, in contrast to elimination programs
where interventions need to be sustained(3). VDPV cases in India may well
raise concerns of popular confidence in the program. Low coverage of
completed RI and missed RI doses in the child with VDPV is a signal that
aggregates of coverage data have created a myth of the machinery while
pockets of unimmunized have sustained the disease in various forms. There
is lack of accurate data of number of pulse doses that an individual child
has received. That such susceptibles are clustered and not random events
indicate that social determinants of the program have not received the
attention that they deserved. Technical strategies, particularly vaccine
related innovations have hogged the limelight in the campaign; serious
biological, social and program management debates have often gone unheard.
Noting wild virus like characteristics of vaccine
derived polio viruses (VDPV) in Egypt, some argued for ‘true eradication’
(definitional perplexities that this campaign has generated!), as ‘zero
incidence of infection with wild and vaccine viruses’(4). The 2009-13
Strategic Plan acknowledged that "VAPP and cVDPVs are inconsistent with
global eradication of paralytic poliomyelitis". That contact-VAPPs and
VDPVs shall cease to be epidemio-logical concerns on cessation of OPV is
probably misplaced, with tens of billions of vaccine viruses released in
the environment.
For the OPV based campaign to achieve elimination of
polio in the foreseeable future several steps are required including
evaluation and modification of key implementation strategies; social
science research leading to social implementation policies that take a
participatory approach, transcending the current social mobilization
framework and, energizing the routine immunization program. Coverage of RI
need not be seen as an end in itself; it provides a valuable marker of the
state of functioning of public health services. None of these is possible
without a responsive and effective primary healthcare system with adequate
social controls. The basic strategy of eradication has continued so far
with only tactical changes made from time to time. This event should
prompt us to address some of what is now entrenched as conventional
wisdom!
Acknowledgement
Sanjay Chaturvedi, Narendra K Arora and Vivek S Adhish.
References
1. AFP Surveillance Bulletin – India. Report for week
24, ending 13th June 2009. URL: http://npspindia. org/bulletin.pdf.
Accessed June 22, 2009.
2. Vaccine Derived Poliovirsues. Global Polio
Eradication Initiative. URL: http://www.polioe radication.org/content/fixed/opvcessation/opvc_
vdpv.asp. Accessed June 22, 2009.
3. Dowdle WR. The principles of disease elimination and
eradication. In Global Disease Elimination and Eradication as Public
Health Strategies. Bull WHO 2008; 76: 22–25.
4. John TJ. Who benefits from global certification of polio
eradication? Indian J Med Res 2004; 120: 431-433.