New data from a study at the University of Oxford provides the first evidence that the COVID-19 vaccine developed by the prestigious school together with AstraZeneca cannot just prevent people from getting sick with the coronavirus, but can significantly help reduce its spread in the community. For the first time in a large-scale human trial, all participants in the UK study were screened for COVID-19 infection at regular intervals after receiving an initial injection of the vaccine, rather than just participants who developed suspected symptoms of the disease.
The Oxford study, posted online Tuesday as an yet-to-be-reviewed peer-reviewed “pre-print” study by The Lancet, found that up to 12 weeks after receiving an initial dose of the vaccine, the number of positive tests with 67 % decreased. among trial participants compared to those who received a placebo.
A number of vaccines, including Oxford / AstraZenecas, the Pfizer and Modern formulas commonly used in the US and others developed all over the world have shown strong efficacy in preventing symptomatic infection, but there is no evidence to date that this would also prevent people from carrying the disease without outward symptoms.
Those asymptomatic carriers have long been considered a high risk for passing the disease on to others, fueling its spread within the population.
For that reason, the latest data out of Oxford has been greeted with great enthusiasm by British leaders, who have placed much of the hope of their mass vaccination program on the Oxford / AstraZeneca vaccine. Nearly 10 million people had received a first dose of COVID-19 vaccine in the UK since Wednesday, many of them with the Oxford injection.
Prime Minister Boris Johnson praised the results as “truly encouraging” and expressed his gratitude to the British scientists and national health workers who drove the UK’s vaccination program, which was one of the first to take off in the Western world.
UK Health Minister Matt Hancock also spoke of the “absolutely excellent” data out of Oxford, telling the BBC on Wednesday that the potential to curb the silent spread of COVID-19 meant the vaccine “would help us all get out of it. pandemic to come ”.
12 week dose gap confirmed
In addition to the evidence on how to prevent asymptomatic infection, the data released by the Oxford scientists on Tuesday supported both Britons’ policies. and European Union drug regulators to leave a gap of up to 12 weeks between the two doses of the Oxford / AstraZeneca vaccine.
The decision raised eyebrows when the UK regulator announced it just before Christmas, despite it being the Oxford recommended interval, as the available data at the time did not clearly show that the vaccine would remain effective during the interval between injections.
But the pre-print study released Tuesday showed that not only did the first injection of the vaccine remain highly effective (72% from 22 days to 90 days after the first dose), it actually appeared to last at least three months. between injections. increase overall efficacy to 82.4%.
In contrast, in subjects who received the second dose of the Oxford vaccine after six weeks, the effectiveness of the drug was only about 55%.
The U.S. Food and Drug Administration has not yet issued an emergency permit for the use of the Oxford / AstraZeneca vaccine. Phase 3 trials are ongoing in humans in the US, as well as in the UK, Brazil and South Africa.
So far, the FDA has shown no tendency to support the longer interval strategy adopted by the UK and Europe if and when it approves the Oxford vaccine, but the latest data from Britain could affect US regulators .
The head of the Oxford Vaccine Group, Professor Andrew Pollard, who is also the lead scientist on the UK trial of the drug, said the data was evidence that the 12-week interval between doses was “ the optimal approach to roll out. , and reassures us that people are protected from 22 days after a single dose. “
CBS News producer Steve Berriman contributed to this report.