The European Union's medicines regulator (EMA) said on Tuesday it has launched a rapid review process for Spanish pharmaceutical firm Hipra's Covid-19 vaccine candidate.
The jab is being developed as a booster for adults who have already been fully vaccinated with a different Covid-19 vaccine.
The decision to begin the "rolling review" was taken after preliminary studies showed the shot is effective against infection against the coronavirus, including the Omicron variant, the European Medicines Agency said in a statement.
Under the rolling review procedure, the data from studies are evaluated in real time, even if not all results are available and no formal application for approval has yet been submitted.
The EMA said it is not yet clear how long the process will take.
Hipra's vaccine contains two versions of the SARS-CoV-2 spike protein that were artificially made in the laboratory.
"When a person is given the vaccine, their immune system will identify the two proteins in the vaccine as foreign and produce natural defences — antibodies and T cells — against them," the EMA said.
"If, later on, the vaccinated person comes into contact with SARS-CoV-2, the immune system will recognize the spike protein on the virus and be prepared to attack it."
Five coronavirus vaccines have already been approved in the EU. The review process for a total of five other vaccines is under way.