Washington, July 29 : American biopharmaceutical company Pfizer has said a third dose of its Covid-19 vaccine can "strongly" boost protection against the Delta variant. Antibody levels against the Delta variant in people aged 18 to 55 who receive a third dose of the Pfizer/BioNTech vaccine are greater than five-fold than following a second dose, according to data posted at the company's teleconference, Xinhua reported. Among people aged 65 to 85, the Pfizer data suggest that antibody levels against the Delta variant after receiving a third dose are greater than 11-fold than following a second dose. Pfizer anticipates applying for emergency use authorization for a third dose of its vaccine as soon as next month, Mikael Dolsten, who leads worldwide research, development and medical for Pfizer, was quoted by CNN as saying at the teleconference. /IANS