MADRID (REUTERS, BLOOMBERG) - An experimental Covid-19 vaccine currently under development by Spanish pharmaceutical firm Hipra could be effective as a booster against variants of the virus, Spain's Science Minister Diana Morant said on Tuesday (Nov 30).

Ms Morant said a Phase II trial on 1,000 volunteers who have already received another vaccine was producing good results on the Alpha and Beta variants of the coronavirus.

She told reporters after the weekly Cabinet meeting that the vaccine would be a possible booster shot against variants.

"Hipra speaks of the ability of its vaccine to recombine variants, and that is one of the improvements that this vaccine presents compared to those that we have been inoculated with so far," she said.

"It is giving very good results precisely because it is a vaccine that recombines the proteins of the Alpha and Beta variants... Delta came later and now we have the Omicron."

Spain's medicines regulator two weeks ago authorised Hipra to carry out Phase II trials of its vaccine, which uses a recombinant protein like that of United States-based drugmaker Novavax.

Before any eventual approval for use in humans, Hipra's vaccine candidate must demonstrate that it is safe and effective in the ongoing tests and at the final Phase III stage of clinical trials.

Merck's molnupiravir

Separately, a Merck & Co's executive said on Tuesday that the company's experimental Covid-19 drug molnupiravir should have similar activity against any new coronavirus variant.

The drug, developed along with Ridgeback Biotherapeutics, shows antiviral properties against coronavirus variants such as the Delta variant, vice-president Daria Hazuda of Merck's infectious diseases and vaccines division said. The comments were part of a general presentation and not specific to the Omicron coronavirus variant.

Regeneron's antibody therapy

Meanwhile, Regeneron Pharmaceuticals said it was conducting further testing after early evidence suggested that its antibody therapy for Covid-19 may be less effective against the Omicron variant.

After some analyses suggested that the variant's mutations may reduce the protection provided by vaccines and monoclonal antibodies, the company said in a statement on Tuesday that it is doing testing "to confirm and quantify this potential impact using the actual Omicron variant sequence".

Regeneron said that its therapy remains highly effective against the Delta variant that is currently responsible for most infections in the US. Omicron has not yet been detected in the country.

It also said other antibody treatments it has in development could prove effective against Omicron.

"Preliminary analyses suggest that several of these next generation antibodies may have the potential to retain activity against the Omicron variant, as well as the other existing variants of concern," said the company.