Thursday, Sep 29, 2022

One trick isn’t enough

Why the malaria vaccine may be bad news in India

The life cycle of the malaria parasite in Anopheles mosquitoes was discovered in India in the 19th century by Ronald Ross,and it won him the Nobel prize in early 20th century. So,mosquitoes transmit malaria. Technically,that is all the information we need to prevent malaria — control mosquito breeding; decimate adult mosquitoes with insecticides; prevent mosquito-human contact. European countries,where malaria was rampant and believed to be due to “mal-air”,applied the new knowledge and eliminated malaria. Add drug therapy and we can prevent mosquitoes picking up the parasites and thus break the transmission cycle.

Unfortunately,we fail to do what we ought to and do what we ought not to. So even in the 21st century,mosquitoes and malaria vex us,particularly in India and in many African countries. In Africa,there are some genuine excuses but India has none — only a lack of political will. We know how to control malaria and we have all the necessary tools; but our health management system is not designed to implement them and monitor progress. In our unfair world,the wages of neglect by the powerful is the death of the powerless.

There is good news in Africa,where a new malaria vaccine has undergone extensive testing. Its birth is an amazing story. It is,in fact,an almost discarded old vaccine,recently resurrected and studied extensively in Africa,funded by the Bill and Melinda Gates Foundation. Compared with many vaccines with protective efficacy in the range of 80-90 per cent and above,the RTS-S malaria vaccine has only about 50 per cent efficacy. Is the cup half empty or half full? If we have another half-full cup,together we have a full cup. With other interventions such as mosquito control,bed-nets treated with insecticide and early diagnosis and treatment in primary health care centres,a vaccine with 50 per cent efficacy is a great additive intervention.

This is great news for Africa,where in some countries,malaria kills young children by the hundreds. Between the two major types of malaria,namely vivax and falciparum,the latter is the rapid killer,the former a slow killer. The vaccine is against falciparum malaria. The countries that participated in the vaccine trials — Burkina Faso,Gabon,Ghana,Kenya,Malawi,Mozambique and Tanzania — will,hopefully,be helped by the Gates Foundation,WHO,vaccine manufacturers and PATH (a US-based NGO) to add vaccination as an adjunct to malaria control.

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I am worried about the consequences of a malaria vaccine in India. True,the malaria problem in parts of Odisha and nearby states is no less than in the worst-affected African countries. Falciparum malaria is invading previously malaria-free territories. Malaria was once exclusively rural,but today urban malaria is a big problem. Last week there was an international electronic media alert that in a Bikaner hospital,the weekly number of malaria admissions increased from 400 to 700 in September. In Jaipur,both vivax and falciparum malaria have increased in 2011 compared with 2010. The annual nation-wide number of malaria deaths is estimated to be 200,000. The malaria “eradication programme” was renamed the “anti-malaria programme”,symbolising the failure to effectively control it.

My fear is that the news about the vaccine may be used as one more excuse. It could easily be said that we have been failing for want of a vaccine; now that we have one,we will use it to control falciparum malaria. So what is wrong with that? Reliance on a vaccine may further weaken clinical and environmental anti-malaria interventions. The vaccine should only be the icing on the cake — of effective early diagnosis and treatment (for which quality primary care and universal access are necessary,but we do not have),a public health disease surveillance system (for which we need public health infrastructure in every district,which we do not have),mosquito-measurement and management plus reduction of vector-human contact (a routine function of public health) and an effective vaccine delivery and outcome-monitoring system (for which we need to re-engineer the national vaccination programme,which has so far achieved nationally only less than 70 per cent coverage in infancy).

If India chooses to make malaria control a national priority,then the addition of a vaccine has great potential. An official of the vaccine manufacturer GlaxoSmithKline has said that one option to reduce the price of the vaccine is mass production in India. The vaccine uses a protein of the parasite’s pre-erythrocytic stage,circumsporozoite,combined with an adjuvant called ASO1. The vaccine has so far been found to be safe (except for minor local and systemic reactions common to all injected adjuvanted vaccines) and immunogenic. Malaria itself does not protect from subsequent malaria. Malariologists know that no antibody,including vaccine-induced circumsporozoite antibody,can be consistently protective. So this vaccine actually beats nature.


The writer was head of the department of clinical virology,Christian Medical College,Vellore

First published on: 28-10-2011 at 03:09:16 am
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