AstraZeneca’s coronavirus vaccine received a major boost on Monday after data from a large trial showed it was safe and effective.
The trials in the US, Chile and Peru showed the vaccine was 79 per cent effective at preventing symptomatic Covid-19 and could bolster confidence in the product after confusion over its efficacy data, dosing regimen and possible side-effects.
They also showed the AstraZeneca drug offered 100 per cent protection against severe disease.
The shot has raised concern in Europe about a possible link to very rare blood clots.
A survey on Monday found Europeans remained sceptical about its safety.
More than a dozen states suspended use of the vaccine over fear about blood clots, although most have resumed its use.
The European Medicines Agency and the WHO ruled the AstraZeneca drug safe and effective.
European countries have also been involved in a row with the pharmaceutical firm over delivery of doses and the EU has threatened to block exports.
Leaders in Asia sought to boost public confidence by taking the AstraZeneca shot themselves amid concerns a slowdown in vaccination distribution could hurt the fight against Covid-19, which has killed more than 2.8 million people worldwide.
The AstraZeneca shot was among the first and cheapest of the Covid-19 vaccines to be developed and launched at volume and is set to be the mainstay of vaccination programmes in many poorer countries.
A total of 32,449 people across all age groups took part in the phase-three trial, with 141 cases of symptomatic Covid-19 reported.
Results showed that among people aged 65 and over, there was 80 per cent protection against developing Covid-19.
The degree of effectiveness against symptomatic Covid-19 was even higher than observed in the Oxford-led clinical trials.
DSMB, an independent data safety monitoring board, also identified no safety concerns relating to the vaccine.
It conducted a specific review of thrombotic events, as well as cerebral venous sinus thrombosis, the specific type of brain blood clot that has been troubling Europe.
The DSMB found no increased risk of thrombosis among the 21,583 participants receiving at least one dose of the vaccine. The specific search for CVST found no cases in this trial.
Andrew Pollard, professor of paediatric infection and immunity and lead investigator of the University of Oxford trial of the vaccine, said: “These results are great news as they show the remarkable efficacy of the vaccine in a new population and are consistent with the results from Oxford-led trials.
“We can expect strong impact against Covid-19 across all ages and for people of all different backgrounds from widespread us of the vaccine.”
Sarah Gilbert, professor of vaccinology and co-designer of the vaccine, said the new findings “provide further confirmation of the safety and effectiveness” of the drug.
“In many different countries and across age groups, the vaccine is providing a high level of protection against Covid-19 and we hope this will lead to even more widespread use of the vaccine in the global attempts to bring the pandemic to an end.”
AstraZeneca will submit data to the US Food and Drug Administration and seek emergency approval for use. The US was waiting for the latest results before considering use of the vaccine.
On Europe’s concerns, Prof Gilbert said: “I’d say the balance remains hugely in favour of using this vaccine. Across Europe there are thousands of deaths a day occurring from Covid.
“It’s really important that we get the chance to protect people as quickly as possible, this vaccine is available for use in Europe and it will save lives.”
Ann Falsey, professor of medicine at the University of Rochester School of Medicine in the US and co-lead principal investigator for the trial, said it was “exciting to see similar efficacy results in people over 65 for the first time”.
“This analysis validates the AstraZeneca Covid-19 vaccine as a much-needed additional vaccination option, offering confidence that adults of all ages can benefit from protection against the virus.”
The US trial saw two doses given four weeks apart, whereas previous trials showed an extended interval of up to 12 weeks demonstrated greater efficacy.
AstraZeneca said an interval longer than four weeks – as is happening in the UK – can increase efficacy and “accelerates the number of people who can receive their first dose”.
As part of an agreement with Oxford University, AstraZeneca is supplying the vaccine on a not-for-profit basis for the duration of the pandemic and in perpetuity for low and middle-income countries.
The news comes as polling for YouGov suggests a drop in confidence in the safety of the vaccine in the last two weeks in Spain, Germany, France and Italy.
About 55 per cent of Germans said the AstraZeneca vaccine was unsafe while 32 per cent said it was safe.
AstraZeneca’s vaccine was already considered unsafe in France but concerns have increased even further, with 61 per cent saying it is unsafe while 23 per cent say it is safe, the survey of almost 9,000 people in seven countries found.
“After concerns about its protection and potency were raised by leaders across Europe, the Oxford-AstraZeneca vaccine has undoubtedly suffered damage to its reputation for safety on the continent,” Matt Smith, lead data journalist at YouGov, said.
“Not only have we seen considerable rises in those who consider it unsafe in the last two weeks in Europe, the AstraZeneca vaccine continues to be seen as substantially less safe than its Pfizer and Moderna counterparts.”