“We have to wait for the results of our own trials before we give approval here. The USFDA approval doesn’t change anything in India. The companies have to do bridging studies here,” said Dr V M Katoach, DG ICMR and Secretary, Health Research.

The vaccines approved in the US are made by Australia’s CSL Ltd., Switzerland’s Novartis, France’s Sanofi-Pasteur and Maryland’s MedImmune, which makes an inhalable vaccine that might be available by the end of the month.

Licensing in the US means the authorities there consider the vaccine meets specific manufacturing and quality standards. The Indian officials insist that vaccine manufacturers will have to conduct limited trials in the country.

The officials are insisting on trials to assess how Indians react to vaccines. “The import of vaccines will also depend on the trial results,” said Dr Katoach.

The Health Ministry, through the ICMR, has written to four international vaccine manufacturers to conduct trials in India. Out of the four, Glaxo SmithKline and Novartis have agreed to conduct the trials provided the government gives them some guarantee of purchase. A third company also agreed to conduct the studies on Wednesday, but officials are not willing to give out the name yet.

The officials said talks are on with other companies as well and the government was working out how many vaccines were likely to needed in the country. The government will be placing orders with foreign companies for procuring vaccines for the health workers, who are first in the line in fighting the disease. The plan so far is to wait for indigenous vaccines.

The licensing in the US was announced after officials from the National Institute of Allergy and Infectious Diseases announced on Friday that the vaccine was safe and produced adequate immunity with only one dose.

Early data on the H1N1 vaccines being tested world over show the vaccines to be highly effective with no adverse effects. Two articles published in the online edition of the New England Journal of Medicine, which have the preliminary data of the H1N1 vaccine, say the single dose vaccines were working in over 95 per cent number of healthy adults.

The data was eagerly anticipated as governments, public health officials, and other stakeholders respond to the first influenza pandemic in over 40 years. The USFDA approval was based on the data from these two studies. The US has ordered vaccine for 195 million doses. About 45 million doses are expected to be available by the middle of October, and officials are targeting those in the highest-risk groups — primarily pregnant women and healthcare workers.