Universalimmunization programme (UIP) in its recent move has decided to introducepentavalent vaccine in selected states.
1 When given separately, it needs 9 shots 3 for DPT+3 for Hep-b +3 forHib to provide protection against all the above-mentioned diseases. Pentavalentvaccine reduces it to 3 shots. Besides providing immunity and protectionquickly and safely, it reduces cost, 1 occupational-environmental hazards aswell as cause less distress and inconvenience for the children and their parents.Active immunization against vaccine preventablediseases have played a crucial role in bringing down the burden of thesediseases and indirectly reducing the cost of medical care involved in treatingthese conditions and their related complications. Presently, on a programmaticbasis, the universal immunization programme (UIP) in India provides freeimmunization services against tuberculosis, poliomyelitis, diphtheria,pertussis, tetanus, hepatitis B, measles, mumps and rubella. The pentavalent vaccine, consisting H. Influenzae B(Hib) component in addition to DPT and Hep B is currently in vogue in privatepractice all across India.
The introduction of this vaccine in governmentprogramme is still in conceptual stages due to a lot of debate regarding thesafety of Hib component in the vaccine. Monitoring and surveillance of AEFI due topentavalent vaccine in the UIP requires in depth analysis before it can beapproved for further use. Very few prospective studies in Maharashtra havetaken incidence of AEFI in pentavalent vaccine recipients as their primaryresearch question. Hence, this study will be conducted toassess the incidence of AEFI among children who received the pentavalentvaccines.
Safety monitoring of vaccines used in routineprogrammes on immunisation is important in all settings. As the rates ofvaccine preventable diseases decrease, even minor common adverse events inchildren causes a lot of concern in the parents. Identification, detection,prevention and appropriate communication of adverse events followingimmunisation (AEFI) are therefore essential to preserve the integrity ofimmunisation programmes and protect public health.To add pneumonia due to Haemophilus Influenzae B (Hib) to the list of vaccine preventablediseases on a national basis the pentavalent vaccine (DPT+HepB+Hib) is proposedto be used. This vaccine is in use by civilian practitioners since a decade. Asa part of Universal Immunization Program, it is introduced in two states only(Kerala and Tamil Nadu), as a pilot project in Dec 2011.
However, there is alot of debate in the country about the relevance of the pentavalent vaccine ingeneral and the Hib component in particular, in view of reports of deaths inchildren following immunization with the vaccine in these two states 3.A public interest litigation (PIL) has also been filed in the Delhi High Courtagainst the use of the vaccine by a group of eminent pediatricians 4.This concern gains more relevance in the light of reports of deaths and severeadverse events following immunization (AEFI) due to pentavalent vaccine usagein Pakistan, Sri-Lanka and Bhutan 4, 5. This vaccine had faced alot of scrutiny and subsequent withdrawal from the govt programme in Sri-Lankain 2008 6.For western countries where the incidence ofcomplicated and serious Hib infections is higher compared to that in Asiancountries, the use of pentavalent vaccine in routine immunization isunderstandable.
In fact, the introduction of the pentavalent vaccine and otherHib containing vaccines have greatly reduced the annual incidence of meningitisand severe Hib pneumonia in countries like USA and Gambia 7, 8 Butin Asia and the Indian sub-continent, it is believed that there is a lot ofnatural immunity in the children under 5 years of age owing to exposure tosubclinical cases and cross-reactivity to other H.Influenzae species. As perone community based study, the incidence of complicated Hib disease in India isas low as 0.
007 percent 9. Also the efficacy of the pentavalent vaccine in comparison to separatelygiven vaccines is low 10. Hence, it is believed that Introductionof this vaccine in the national programme in the face of proven low incidenceof invasive disease, absence of benefit from Hib vaccination demonstrated inthe probe studies from Asia and the evidence of strain replacement in the West,appears to be a profligate exercise in futility 11.DPT is an established combination vaccine used inIndia on a backdrop of high disease burden and adequate country specificresearch. And any new vaccine finds it convenient to get combined with DPT andget introduced into the markets. But combination vaccines should be introducedonly after a lot of scrutiny and deliberate understanding of the ‘profit’ ofsingle visit by parents for vaccinating against multiple diseases versus the’loss’ of safety and efficacy.
For example, the varicella vaccine incombination with MMR was tried, but resulted in raised instances of febrileseizures in the recipients 12. Similarly, for adults, thecombination of hepatitis A with typhoid vaccine proved inefficient incomparison to both the vaccines given separately 13. Using a combination of Hep B and Hib alongwith DPT thus raises further questions.However, the argument against the anticipatedapprehensions of AEFI in pentavalent vaccine recipients is that the state ofGoa has been using it in state funded immunization program without anydifficulty of reports of severe AEFI/deaths. Same is the case with privatepractitioners, but authentic data in this group is not readily available.Several studies conducted on the issue in developing countries also reflect asimilar opinion 14. The UNICEF suggests that that in remote areaswith poor access to medical care, 10 per cent cases of pneumonia die 15.In the Sri Lankan episode of 2008 mentioned earlier,a detailed investigation by the WHO revealed that no serious AEFI wereattributable to the vaccine as such 6.
The non-fatal but seriousAEFI like the hypotonic-hypo responsive episode (HHE) did occur, but it is anestablished side effect of Pertussis (whole cell), Hep B as well as Hibvaccines. In Sri Lanka, the survey concluded, in comparison to the previousfour years, there had been an increased reporting of deaths temporallyfollowing vaccination in 2008. The reasons for increased reporting are unclear,but the number of deaths temporally following vaccination is not above whatwould be expected by chance alone based on the background neonatal and infantmortality rates. Further, the panel concluded based on its preliminary reviewof the “HHE-like” cases reported in Sri Lanka that although HHE wasapparently unrecognized in Sri Lanka prior to the use of the liquid pentavalentvaccine, the reported cases do not show an increase above the expectedreporting rate of HHE following similar vaccines.Further, the WHO also recommends that the H.Influenzae conjugate vaccine should be included in routine immunizationprogrammes 16. However, some authorities believe that such auniversal advocacy by the WHO for a disease which has varied epidemiologicaltrends country-wise and without accounting for limited resources of countrylike India is questionable 17.Thus the present environment in the country isreeked with lack of faith in the vaccine at the national level on one side andthe advocacy of making it available to the poorer classes free of cost on theother.
The surveillance and reporting ofAEFI has thus become a highly relevant issue in current scenario 18. It may be the reasonitself (causal association), or, there might be some other factors (temporalassociation/coincidental adverse event) for which the complications arereported. Adverse events following immunization (AEFI) are well establishedwith DPT, Hep-B and Hib vaccine separately in various studies but when given incombination as pentavalent vaccine, data on AEFI with this is still lacking. If there is any reduction in proportion ofvarious minor and major AEFI after pentavalent Vaccination in comparison toseparate vaccines? It is utmost important to monitor reactogenicity of vaccineused in immunization programme. To establish and maintain the faith ofcommunity in immunization programme, identification, detection, prevention andappropriate communication is necessary.
19Theterm “AEFI” merely denotes a temporal relationship between vaccination andadverse events. This relationship need not to be causal from an expert point ofview. But community mostly perceived it as causal.19