The Pfizer company announced Wednesday that a third dose of their COVID-19 vaccine “strongly” boosts protection against the Delta variant.

Data published online indicate that levels of antibodies against the delta variant in people aged between 18 and 55 who have received a third dose of the vaccine are five times higher than those who received the second dose only.

Among people aged 65 to 85, Pfizer data indicate that levels of antibodies against the delta variant after receiving a third dose of the vaccine are 11 times higher than after receiving a second dose only.

"Receiving a third dose more than six months after vaccination, when protection may be beginning to wane, was estimated to potentially boost the neutralizing antibody titers in participants in this study to up to 100 times higher post-dose three compared to pre-dose three," according to Dr. Mikael Dolsten, who leads worldwide research.

"These preliminary data are very encouraging as Delta continues to spread."

The data was published online as part of a company presentation and has not undergone scientific review.