Vaccine 23 (2005) 3097–3098

Correspondence

Evaluation of OPV efficacy is required for polio eradica-tion in India

In 1988, the World Health Assembly passed resolutionWHA 41.28, which committed the World Health Organiza-tion (WHO) to global eradication of poliomyelitis by the year2000, by providing immunization exclusively with oral po-lio vaccine (OPV). Dead line for polio eradication has beenpostponed many times.

Dr. Jacob John had stated: “The number of districts withpolio had declined to 63 in 11 states in 2001, but in 2002 casesoccurred in 146 districts in 16 states. Kerala, Tamil Nadu,Andhra Pradesh and Karnataka remained unaffected, in thesestates, routine and pulse immunizations have remained ro-bust through the years”[1]. But during the year 2003, wild

Table 1Number of OPV doses received by polio cases, 1998–2003

OPV doses 1998 1999 2000 2001 2002 2003

0 (%) 13 13 14 9 15 141–3 (%) 40 43 28 31 41 3>4 (%) 33 40 58 60 44 51

Data as on 13th December 2003.Source:January 2004 issue of Bulletin ofPolio Eradication Committee of the Indian Academy of Pediatrics.

2. Failure to prevent polio

In a study from a Sentinel Centre for 1989–1994 period,it was reported that the number of children who developedparalytic polio after being fully immunized with three or moredoses was 14% in 1989 and increased to 22.9% in 1994[3].

ve7%

PVlio

il-set

polioviruses emerged in Tamil Nadu, Andhra Pradesh andKarnataka. Resurgence of wild polioviruses in India suggeststhat there were some deficiencies in the vaccine and/or thestrategy.

All those associated with polio eradication programme inIndia attribute “failure to vaccinate all”, and not “vaccinefailure” as the reason for failure of the programme. Efficacyof any vaccine should be evaluated on the basis of the balance

In Rajasthan, the number of children who had received fior more doses of OPV before onset of paralysis was 32.in 1999[4] and 58.6% in 2000[5].

Percentage of polio cases according to number of Odoses received from 1998 to 2003 as per National PoSurveillance Project (NPSP) data are given inTable 1. Ina study by Kohler et al., out of 181 VAPP cases, 78 chdren had received five or more doses of OPV before on

between the positive and the negative contributions made bya vaccine in terms of prevention of the disease, failure to

y thehowanyPV

(iii)litis

offorainstafter00%,

te the

of paralysis[6]. The authors had stated: “It is also possiblethat OPV administered in India was of lower potency andthat deficiencies in the cold chain were responsible for re-duced potency.” According to the study by Kohler et al. outof 60 recipient VAPP cases nine had developed paralysis afterfirst dose while rest had developed paralysis after subsequentdoses, suggesting that OPV doses administered before theculprit dose had failed to provided any protection to the vac-cine recipients.

3

ears1

TN

Y 02C 3

d.

. VAPP

According to NPSP figures of VAPP cases for the y998–2002 are given inTable 2.

able 2umber of VAPP cases

ear 1998 1999 2000 2001 20ases 124 206 151 120 20

prevent the disease and the adverse effects caused bvaccine. For OPV the parameters to be evaluated are: (i)many cases of polio have been prevented? (ii) how mcases of polio occurred inspite of adequate number of Odoses i.e. failure to prevent polio or vaccine failure? andhow many cases of vaccine associated paralytic poliomye(VAPP) have been caused by OPV?

1. Prevention of polio

According to a small study by Jaiswal et al. consisting144 children, which included 27 unvaccinated children1996 and 1997 period, the percentage seropositivity agP1, P2 and P3 was found to be 55.2%, 37.9% and 86.2%3 doses; 61.1%, 47.2% and 94.4% after 5 doses; and 184.7% and 100% after 7 doses respectively[2]. No largeserological studies have been done since then to evaluaantibodies generated by OPV.

0264-410X/$ – see front matter © 2005 Elsevier Ltd. All rights reservedoi:10.1016/j.vaccine.2004.10.049

3098 Correspondence / Vaccine 23 (2005) 3097–3098

According to Dr. Jacob John 60–75 VAPP cases were ex-pected to occur every year in India[7]. According to theestimates by the author, about 300 VAPP cases occur everyyear[8].

4. Conclusions

It appears that because of some recommendations regard-ing AFP classifications many compatible polio cases andVAPP cases are being missed[8], but even according to theofficial data there is high incidence of vaccine failure withOPV and incidence of VAPP is unacceptably high. Reasonsfor vaccine failure are not known, but vaccine failure andnon-availability of IPV are the reasons for high incidence ofVAPP. OPV is administered to prevent polio, but no stud-ies have been done to determine whether OPV is providingprotection to the vaccine recipients. The children who had re-ceived OPV and have not developed paralytic polio, it is beingpresumed that these children were protected by the vaccine.On the other hand it could be due to lack of infection, becauseof improvement in hygiene and sanitation or due to immunityprovided by the wild polioviruses circulating in the commu-nity that these children have not developed polio. There isan urgent need to evaluate the efficacy of the vaccine so thata ndia.

References

[1] John TJ. Polio eradication in India: what is the future? Indian Pediatr2003;40:455–63.

[2] Jaiswal S, Jana AM, Tharwani YP, Belapurkar KM. IgG antibodyresponse to oral polio vaccine (OPV) immunization. Indian J MedMicrobiol 2000;18:79–82.

[3] Ahuja B, Gupta VK, Tyagi A. Paralytic poliomyelitis (1989–1994):report from a Sentinel Centre. Indian Pediatr 1996;33:739–45.

[4] Paul Y. Polio eradication strategy: need for re-appraisal. Indian Pediatr2000;37:913–6.

[5] Paul Y. Accuracy of national polio surveillance project data in Ra-jasthan. Indian J Pediatr 2002;69:667–73.

[6] Kohler KA, Bannerjee K, Hlady WG, Andrus JK, Sutter RW. Vaccineassociated paralytic poliomyelitis in India during 1999: decreased riskdespite massive use of oral polio vaccine. Bull WHO 2002;80:210–26.

[7] John TJ. Can we eradicate poliomyelitis? In: Sachdeva HPS, Choud-hury P, editors. Frontiers in Pediatrics. New Delhi, India: JaypeeBrothers; 1996. p. 79–90.

[8] Paul Y. Need for re-appraisal of acute flaccid paralysis (AFP) caseclassification. Vaccine 2004;22:3829–30.

Yash PaulA-D-7, Devi Marg, Bani Park

Jaipur 302016, IndiaE-mail address:dryashpaul2003@yahoo.com

3 May 20045

ppropriate measures be taken to eradicate polio from I Available online 29 January 200