Out of 800 trial participants in South Africa, only nine got sick which included six with the B.1351 variant.
People who are fully vaccinated against COVID-19 can safely travel within the United States and overseas as long as they continue to take precautions like wearing a mask in public, according to new guidance released Friday by the the Centers for Disease Control and Prevention.
Meanwhile, research, led by the University of Birmingham and including Public Health England's Porton Down laboratory, found 98% of people aged 80 or over who had two doses of the Pfizer jab had a strong antibody immune response.
On Wednesday, the companies said a small trial of volunteers aged 12 to 15 showed 100% efficacy in that age group.
"These data confirm the favorable efficacy and safety profile of our vaccine and position us to submit a Biologics License Application to the U.S. FDA", said Albert Bourla, chairman and CEO of Pfizer. For the study, the team conducted a survey of 1,090 healthcare workers at Cedars-Sinai who had received the Pfizer-BioNTech vaccine.
Although the new study did not look at the Oxford University/AstraZeneca vaccine, Prof Moss said the evidence for the jab is that "it's very, very effective".
More encouraging developments from Pfizer on Thursday morning, a longer-term study of its vaccine shows a high-level of effectiveness against more infectious COVID-19 variants.
The firms said that of these cases, 850 occurred among participants who got the placebo, while 77 were in the vaccinated group.
The Pfizer and BioNTech vaccine is normally administered in two doses, 21 days apart, to provide almost full protection against the novel coronavirus, known as SARS-CoV-2.
"The antibody levels were so high that they'd gone above the thresholds so they had to dilute them".
Professor Paul Moss, from the University of Birmingham and leader of the UK Coronavirus Immunology Consortium, told a briefing he was surprised how well the vaccines have worked in older people.