To start clinical trials for influenza A H1N1 vaccine, two pharmaceutical companies have formally sought permission from the Indian Council of Medical Research (ICMR).
According to sources in the ministry, the companies are Cadilla Pharmaceuticals in Ahmedabad and Serum Institute of India in Pune.
Both the companies have reportedly sought permission to conduct trials based on an alternative approach.
Serum Institute has used live virus instead of the conventionally used killed virus for vaccine trials.
However, Bharat Biotech in Hyderabad and Panacea Biotec in Delhi have also sought the permission, but for the normal method of trial.
Meanwhile, with 42 fresh cases reported over the weekend, the number of swine flu affected persons in Delhi reached 4,042.
There have been 18 deaths in the city so far.
The total number of affected persons across the country hit 16,540, with 200 new cases on Sunday.
The number has been highest reported till now in the month of November.