Moderna Inc. said Tuesday its COVID-19 vaccine produced protective antibodies against the delta variant spreading in the U.S. and many other parts of the world.

Moderna researchers tested blood samples from eight people for antibodies against versions of the spike protein from different coronavirus variants, including delta, which emerged in India. The vaccine “produced neutralizing titers against all variants tested,” the company said in a statement. The results were released on the pre-print server bioRxiv.

The protective proteins are called neutralizing antibodies because they’re capable of preventing the virus from entering cells. Compared to the quantity of antibodies produced against the main version of the virus, neutralizing antibody levels against the delta variant were reduced by 2.1-fold.

Shares of Moderna gained 5.9% at 10:24 a.m. in New York.

Antibody levels were reduced by 4.2-fold against the eta strain first found Nigeria, and by eight-fold against a new variant identified in Angola called A.VOI.V2.

The lab-based study did not directly measure vaccine effectiveness. Although reduced, the neutralizing antibody levels are still thought to be high enough to prevent disease, as the messenger RNA vaccine generates a strong immune reaction that creates a surplus of antibodies against the original strain.

“We remain committed to studying emerging variants, generating data and sharing it as it becomes available. These new data are encouraging and reinforce our belief that the Moderna Covid-19 vaccine should remain protective against newly detected variants,” Moderna CEO Stephane Bancel said in the statement.

Moderna earlier published research showing its vaccine produces neutralizing antibodies against the alpha, beta, and gamma variants that emerged in different regions.