Need of minimum cold chain dependent Veterinary Vaccines
Sangeeta Das1*, Anu Malik1, Pankaj Deka2
1PhD Scholar, Department of Microbiology, LUVAS, Hisar, Haryana-125001
2Assistant Professor, Department of Microbiology, CVSc, AAU, Khanapara, Guwahati-781022
- sangitakashyap9864@gmail.com
- In India, history of agriculture dates back to the Indus Valley Civilization. Agriculture and allied sectors like animal husbandry, forestry and fisheries plays a significant role in the overall socio-economic fabric of the country. Livestock plays an important role in Indian economy. Livestock provides livelihood to a fifth of landless and nearly 10% of marginal farmers. Livestock enterprises support a sizeable chunk of livelihood in urban community too. It provides employment to about 8.8% of the Indian population. Besides contribution to sustainability, livestock sector contributes 4.11% Gross domestic product (GDP) and 25.6% of total agriculture GDP. However, a significant obstacle for the growth in terms of production from livestock including poultry is the prevalence of some infectious diseases. Among them, Foot and mouth disease (FMD), Peste des petits ruminants (PPR), Brucellosis, Haemorrhagic Septicemia (HS), Classical swine fever (CSF), Newcastle disease (ND), Avian Influenza (AI) etc are devastating and highly contagious diseases of livestock and poultry causing serious economic losses.
The only effective measure to curb the economic menace of these infectious diseases is by biosecurity measures and effective vaccination. Veterinary vaccines are a cost-effective method to prevent animal diseases, and reduce or prevent transmission of zoonotic diseases. The concerted global efforts to eradicate livestock diseases have resulted in the development of vaccines over the decades. The global Rinderpest eradication highlights the value of vaccines. The conventional veterinary vaccines have stood the test of time by offering protective efficacy against infectious diseases. Most currently available vaccines, particularly the live vaccines are thermolabile demanding the cold-chain maintenance from production to administration. These thermolabile vaccines require storage at a temperature range of 2-8C at all times to maintain their efficacy, which is challenging under village conditions or remote areas that are often beyond the reach of the cold chain. The disruption of the cold chain leads to rapid loss of potency or administration of ineffective vaccines resulting in vaccination failure and thus, the biggest contributor of vaccine wastage. Up to 80% of the cost of vaccination programme is consumed by the cold-chain infrastructure, which includes staff to manage the vaccine distribution, equipment for vaccine storage and transport, maintenance of that equipment, and effective monitoring of the system. Moreover, the cold chain is not always reliable. Temperature excursions outside the optimal temperature range are frequently observed during transport and storage due to inappropriate cold-chain equipment, human errors, and interrupted power supplies. This necessity places a tremendous financial and logistical burden on vaccination programs, particularly in the developing country. It is estimated that roughly 50% of vaccine products are discarded due to disruption of the cold chain.
The development of thermostable vaccines can greatly ease this problem by facilitating vaccine coverage gains in remote areas and significantly reducing the cost of vaccination programs. Thermostable veterinary vaccines indeed can be an important contribution in disease control programs, particularly in developing countries. Several attempts based on reverse vaccinology, use of chemical stabilizers and addition of stabilizing adjuvants followed by freeze drying are made to develop a vaccine that could be used in the field without refrigeration. The existing PPR vaccines although provide life-long immunity, requires continuous refrigeration to be effective. Studies report the use of a thermostable Vero cell-adapted rinderpest vaccine as a suitable immunogen for protection of goats against PPR. Hester Biosciences developed a thermostable PPR vaccine that can withstand 400 C for up to 5 days, eliminating the need of cold chain from production to distribution. Another study reported freeze-dried thermostable live attenuated buffalo vaccine prepared with an indigenous buffalopox virus isolate (BPXV Vij/96) and different stabilizer combinations. Similar study described a lyophilized live-attenuated CSF virus vaccine formulation that remained stable at 370 C for 25 days and 450 C for 2 weeks. A collaborative project between ICAR-IVRI and ICAR-Directorate of FMD evaluated an improved thermostable mutant (IND R2/1975mut) FMD serotype O vaccine strain for use in cattle. In poultry, the ND V4-HR and ND I-2 are naturally thermostable avirulent ND virus (NDV) strain used as live thermostable ND vaccine in many countries in Africa and Southeast Asia. Hester Biosciences developed freeze dried LaSota strain of NDV that is stable at 370 C for a duration of 10 days.
The cold chain remains a highly vulnerable point for vaccination programmes in developing countries, especially remote areas. The livestock sector certainly needs more research to harness new technology to develop thermostable vaccines and contribute to protect smallholders, farmers and their livelihoods in developing countries.
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