New Delhi – The challenge with the Pfizer’s COVID-19 vaccines is that, how long the immunity lasts and how much protective value that it gives as far as individuals are concerns, said AIIMS Director (Delhi) Dr Randeep Guleria.

AIIMS Director said that the data released by the company is very encouraging but it should be looked very carefully.Dr Randeep Guleria also said that other challenge with the Pfizer COVID-19 vaccine is that the vaccine should be kept at a very low temperature which is not practical for rural parts of India and tough to maintain the cold chain.