* Looking for signs that warrant a vaccine redesign

* BioNTech says understands experts' concerns

* BioNTech, Pfizer in effort to establish relaunch routine (Adds detail, shares)

By Ludwig Burger

FRANKFURT, Nov 26 (Reuters) - BioNTech, the inventor of the western world's most widely used COVID-19 vaccine, said it expects more data on a worrying new coronavirus variant detected in South Africa within two weeks to help determine whether its shot would have to be reworked.

"We understand the concern of experts and have immediately initiated investigations on variant B.1.1.529," the biotech firm, which is in a vaccine alliance with Pfizer, said in a statement when asked to comment.

"We expect more data from the laboratory tests in two weeks at the latest. These data will provide more information about whether B.1.1.529 could be an escape variant that may require an adjustment of our vaccine if the variant spreads globally," it added.

Escape variants are those that elude the targeted immune response brought about by vaccination. Should it be necessary, Pfizer and BioNTech would be able to redesign their shot within 6 weeks and ship initial batches within 100 days, BioNTech added.

BioNTech shares gained 7%, while Pfizer stock was up more than 5% in pre-market trading.

Global authorities reacted with alarm on Friday to the new variant, with the EU and Britain among those tightening border controls as scientists sought to find out if the mutation was vaccine-resistant.

Pfizer and BioNTech have already created versions of their established mRNA-based vaccine - based on the original virus found in the Chinese city of Wuhan - to target the so-called Alpha and Delta variants, with clinical trials ongoing.

While not meant to yield commercial products, the exercise is carried out to establish a routine with regulators that will help speed up any future vaccine relaunch. (Reporting by Ludwig Burger; Editing by Maria Sheahan, Kirsten Donovan)