Pfizer Inc has it may file for US authorisation of the Covid-19 vaccine it is developing with German partner BioNTech in late November, making it unlikely a vaccine will be available before the US election as President Donald Trump has promised, Reuters reported.

Pfizer said that it may say if the vaccine is effective as soon as this month based on its 40,000 person clinical trial but that it also needs safety data that will not be available until November at the earliest.

The Pfizer news, published in a letter from its chief executive on its website, lifted the US stock market and the company's shares. Shares were up slightly in rival vaccine maker Moderna Inc, which is close to Pfizer in its vaccine development.