At 1.30 pm, the shares pared some gains and were trading 5.03 per cent higher at Rs 5,165.40.
In early trade, Pfizer shares had surged as much as 19.5 per cent to an all-time high of Rs 5,875.
Pfizer and German partner BioNTech said they had found no serious safety concerns yet and expected to seek US emergency use authorization this month, raising the chance of a regulatory decision as soon as December, an announcement that triggered hopes worldwide.
The two companies estimate they can roll out up to 50 million doses this year, enough to protect 25 million people, and then produce up to 1.3 billion doses in 2021, if they are granted approval.
The announcement was cheered by world markets, as hopes emerged for a protection against the deadly Covid-19 virus that has killed more than a million people across the globe, and have battered world economy and businesses.
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