July 20 (UPI) -- COVID-19 vaccine candidates at Britain's Oxford University and U.S. pharma company Pfizer each show promise, according to new results reported Monday.
Oxford and its partner, European drug maker AstraZenaca, released data in the medical journal The Lancet showing a strong immune response in a large, early-stage human trial.
Researchers said their candidate, ChAdOx1 nCoV-19, shows an "acceptable safety profile" and "homologous boosting increased antibody responses."
Neutralizing antibodies that target the coronavirus that causes COVID-19 were detected in 91% of the trial's 35 participants after a single dose, they added, and the antibodies were still present after 28 days.
"These results, together with the induction of both humoral and cellular immune responses, support large-scale evaluation of this candidate vaccine," the study's authors said.
Pfizer and partner BioNTech released positive data for safety and immune response for one of their candidates, BNT162b1.
The data showed that two doses of the vaccine produced "robust" T cell and antibody responses in COVID-19 patients, "clearly above" convalescent human serum, which is derived from the blood of patients who have recovered from the disease.
Researchers said the results, compiled from a trial involving 60 healthy volunteers in Germany, suggest "multiple beneficial mechanisms with potential to protect against COVID-19."
Pfizer and BioNTech said last week they'd received "fast track" designation from U.S. regulators for BNT162b1 and another vaccine candidate.
The companies are evaluating at least four potential vaccines in the BNT162 program, all based on an mRNA, or messenger RNA, technique -- which, unlike traditional vaccines, does not use an inactivated virus but rather a portion of the coronavirus' own genetic code to spur production of antibodies.