New Delhi, Aug 9 - India is expected to be among the first few countries to develop an indigenous, injectable swine flu vaccine and the government has already invited health centres to carry out human trials, says a top health official.

'We are not bothered about what is happening abroad. Our government has a plan to have indigenous vaccine by the end of this year and we will be among the first few countries to have such a vaccine to tackle the H1N1 virus,' V.M. Katoch, secretary in the department of health research, told IANS in an interview.

'India started working on a vaccine from April soon after the pandemic broke out abroad. At least three companies are working on the vaccine. One company has made real progress and we believe by November, we will have something in hand,' he added.

Katoch said the vaccine will be available in the market in an injectable format by the year-end.

Over the last couple of months, India has reported over 700 cases of swine flu, with Delhi and Maharashtra being the worst hit. Both the states have reported over 50 percent of the total cases in the country.

'The WHO has made available four strains and the drug controller (of India) has approved them all. Based on this, the vaccine is being developed at three places across the country.

'Three pharma companies - Serum Institute of India (Pune), Bharat Biotech (Hyderabad) and Panacea Biotech (New Delhi) - are working on developing the vaccine. The Pune company has made some real progress,' he said.

While the Serum Institute is developing an 'egg-based' vaccine, the other two are developing 'cell line vaccines'.