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T Jacob John

Publications and source records attributed to T Jacob John.

At least 19 recordsLinked to original sources
PubMed2005

Hepatitis B vaccine boosters: is there a clinical need in high endemicity populations?

The Steering Committee for the Prevention and Control of Infectious Diseases in Asia recently conducted a survey of primary-care physicians in Asia, which revealed that many physicians administer boosters in their clinical practice and that there is considerable variation and uncertainty among physicians regarding this practice. This paper serves as a response to physicians' uncertainties by reviewing the literature regarding the administration of hepatitis B vaccine boosters in high endemicity areas and presenting the Steering Committee's guidelines for booster administration. While there are few data to support a need for routine hepatitis B vaccine boosters as a public health measure, they help to provide reassurance of immunity against breakthrough infection in certain risk groups. In clinical practice, primary-care physicians must exercise their judgment regarding the need for booster vaccination on an individual basis. This paper examines the available literature on the administration and value of hepatitis B vaccine boosters, explores the differences between the public health approach and clinical practice, and provides guidelines for those who use boosters in high endemicity Asian populations. Relevant articles were identified through searches of MEDLINE (1975-2003) and the Cochrane Library, using 'hepatitis B' and 'booster' as primary search terms. Guidelines for those who decide to administer hepatitis B vaccine boosters include: boosting approximately 10-15 years after primary vaccination; boosting rather than not when monitoring of antibody levels is not feasible; boosting immunocompromised patients when the antibody to hepatitis B surface antigen titer falls below 10 mIU/mL; and boosting healthcare workers based on the endemicity of the particular country.

Endemic Diseases↗
PubMed2004

A developing country perspective on vaccine-associated paralytic poliomyelitis.

When the Expanded Programme on Immunization was established and oral poliovirus vaccine (OPV) was introduced for developing countries to use exclusively, national leaders of public health had no opportunity to make an informed choice between OPV and the inactivated poliovirus vaccine (IPV). Today, as progress is made towards the goal of global eradication of poliomyelitis attributable to wild polioviruses, all developing countries where OPV is used face the risk of vaccine-associated paralytic poliomyelitis (VAPP). Until recently, awareness of VAPP has been poor and quantitative risk analysis scanty but it is now well known that the continued use of OPV perpetuates the risk of VAPP. Discontinuation or declining immunization coverage of OPV will increase the risk of emergence of circulating vaccine-derived polioviruses (cVDPV) that re-acquire wild virus-like properties and may cause outbreaks of polio. To eliminate the risk of cVDPV, either very high immunization coverage must be maintained as long as OPV is in use, or IPV should replace OPV. Stopping OPV without first achieving high immunization coverage with IPV is unwise on account of the possibility of emergence of cVDPV. Increasing numbers of developed nations prefer IPV, and manufacturing capacities have not been scaled up, so its price remains prohibitively high and unaffordable by developing countries, where, in addition, large-scale field experience with IPV is lacking. Under these circumstances, a policy shift to increase the use of IPV in national immunization programmes in developing countries is a necessary first step; once IPV coverage reaches high levels (over 85%), the withdrawal of OPV may begin.

Child↗
PubMed2004

Treatment failure in typhoid fever with ciprofloxacin susceptible Salmonella enterica serotype Typhi.

Fluoroquinolones are considered the most effective drugs for the treatment of typhoid fever and hence are widely used in the empiric treatment of acute undifferentiated febrile illnesses in India. Recent reports of Salmonella enterica serotype Typhi (S. Typhi) strains with increasing minimum inhibitory concentration (MIC) of ciprofloxacin have raised the fear of potential treatment failures. In this case series of 109 consecutive patients hospitalized with typhoid fever (S. Typhi grown from blood), we documented clinical failure (fever persisting >6 days) in 25 of 46 (54.3%) adults who could be evaluated. Among these, eight (17.4%) had microbiological failure (S. Typhi recovered from blood after 6 days of ciprofloxacin therapy) despite adequate serum ciprofloxacin levels, and all required alternative drugs for treatment. These 8 S. Typhi strains, although susceptible to ciprofloxacin (MIC < 1 microg/mL) (NCCLS 2000), had MICs (median MIC 0.5 microg/mL) that were increased 15-fold compared to S. Typhi strains from patients with typhoid fever seen at our center in 1995 (median MIC 0.032 microg/mL), and were nalidixic acid resistant S. Typhi (NARST) (MIC > or =32 microg/mL). The poor treatment outcomes with ciprofloxacin therapy in patients infected with NARST strains that exhibit an increased ciprofloxacin MIC call for a need to revise the ciprofloxacin breakpoints for S. Typhi.

Adolescent↗
PubMed2004

A global perspective on vaccine safety and public health: the Global Advisory Committee on Vaccine Safety.

Established in 1999, the Global Advisory Committee on Vaccine Safety advises the World Health Organization (WHO) on vaccine-related safety issues and enables WHO to respond promptly, efficiently, and with scientific rigor to issues of vaccine safety with potential global importance. The committee also assesses the implications of vaccine safety for practice worldwide and for WHO policies. We describe the principles on which the committee was established, its modus operandi, and the scope of the work undertaken, both present and future. We highlight its recent recommendations on major issues, including the purported link between the measles-mumps-rubella vaccine and autism and the safety of the mumps, influenza, yellow fever, BCG, and smallpox vaccines as well as that of thiomersal-containing vaccines.

Advisory Committees↗
PubMed2004

The golden jubilee of vaccination against poliomyelitis.

Inactivated poliovirus vaccine (IPV), developed in the USA by Jonas Salk in the early 1950s, was field tested in 1954, and found to be safe and effective. The year 2004 marks the golden jubilee of this breakthrough. From 1955 IPV was used extensively in the US and polio incidence declined by more than 95 per cent. However, in 1962, when oral poliovirus vaccine (OPV) became available, the national policy was shifted to its exclusive use, for reasons other than science and economics. The World Health Organisation (WHO) also adopted the policy of the exclusive use of OPV in developing countries. Thus IPV fell into disrepute in much of the world, while Northern European countries continued to use it. New research led to improving its potency, reducing its manufacturing costs and combining it with the diphtheria-tetanus-pertussis (DTP) vaccine to simplify its administration and reduce programmatic costs. All countries that chose to persist with IPV eliminated poliovirus circulation without OPV-induced polio or the risk of live vaccine viruses reverting to wild-like nature. IPV is highly immunogenic, confers mucosal immunity and exerts herd protective effect, all qualities of a good vaccine. It can be used in harmony with the extendend programme on immunization (EPI) schedule of infant immunisation with DTP, thus reducing programmatic costs. During the last ten years IPV has once again regained its popularity and some 25 industrialised countries use it exclusively. The demand is increasing from other countries and the supply has not caught up, leaving market forces to dictate the sale price of IPV. Anticipating such a turn of events India had launched its own IPV manufacturing programme in 1987, but the project was closed in 1992. Today it is not clear if we can complete the job of global polio eradication without IPV, on account of the genetic instability of OPV and the consequent tendency of vaccine viruses to revert to wild-like properties. The option to use IPV is complicated since it is not yet licensed in India, we do not manufacture it and imported vaccine would be prohibitively costly. However, in this golden jubilee year we have much to celebrate as the global eradication of wild polioviruses is within sight. Had we strictly followed the principles of science and health economics, perhaps we could have achieved success earlier and cheaper, with the absence of vaccine-induced polio as the bonus.

Biotechnology↗