Leading candidates in the race for a coronavirus vaccine have removed the first hurdle.
In the first human tests, the vaccine programs led by AstraZeneca, Pfizer and Moderna were successful in generating immune responses in healthy volunteers. The researchers described each program as generally safe and tolerable, supporting more testing for each shot.
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AstraZeneca became the last to publish early human data, publishing its first clinical results on Monday in The Lancet. The vaccine was administered to 543 volunteers.
But only a few dozen people were screened for neutralizing antibodies, the virus-fighting proteins that play a crucial role in the body’s immune response. One month after receiving a dose of the vaccine, 32 of 35 people had these proteins.
Ten volunteers also tested a two-dose regimen that included a booster shot. All 10 people had neutralizing antibodies, and the vaccine’s top researchers emphasized these limited results.
“We saw the strongest immune response in participants who received two doses of the vaccine, indicating that this could be a good strategy for vaccination,” said Andrew Pollard, co-author of the trial.
The researchers reported no serious vaccine side effects, but 70% of the vaccinated volunteers experienced fatigue and 68% had headaches, higher rates than a control group that received a meningitis vaccine.
The study was limited to young, healthy people. The median age was 35 years and 91% of the volunteers were white.
“There is still a lot of work to be done before we can confirm whether our vaccine will help control the COVID-19 pandemic, but these early results are promising,” Oxford University professor Sara Gilbert said in a statement Monday. .
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Initial positive results still do not determine if the vaccine works
It is unclear what level of immune response will protect people from the virus. Large-scale trials, enrolling tens of thousands of people, are now underway to test the AstraZeneca vaccine in the UK, South Africa, and Brazil. The British drug maker also aims to start a late-stage trial in the United States in August.
These final tests will determine if the vaccine can really prevent infection or disease, comparing vaccinated volunteers with a group receiving a placebo.
Moderna plans to begin its final testing phase on July 27, and Pfizer executives said they also hope to launch their fundamental study this month. Additional vaccine candidates led by Johnson & Johnson and Novavax are aiming to start these large efficacy trials this fall.
All of these programs pursue an unprecedented schedule in vaccine development. It usually takes several years to manufacture a vaccine, test it in trials, and manufacture the injection at scale. Given the urgency of the pandemic, drug makers have been working closely with world governments to shorten that process to a matter of months.
AstraZeneca, Pfizer and Moderna have said they hope to be ready as early as this fall for possible emergency use of their vaccines. Their vaccines would be very limited in quantity, and it is unclear how much clinical data would be available to support a regulatory decision so soon.
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Oxford scientists developed the injection to avoid pre-existing immunity problems
The shot was developed by scientists at Oxford University. They put together a chimpanzee version of the common cold virus, called adenovirus, to transport the spike protein, a critical element of the new coronavirus. The scientists used a chimpanzee version of the virus to avoid any pre-existing immunity concerns to the adenovirus.
This problem arose for another early candidate for the coronavirus vaccine developed by Chinese biotech CanSino Biologics. That program used a human adenovirus, and about half of the human volunteers had pre-existing immunity to that virus. This weakened the immune response to the vaccine, according to clinical results published in May.
AstraZeneca joined the effort in late April and supercharged its manufacturing and testing strategy. That has included signing a $ 1.2 billion deal with the U.S. government, supplying up to 400 million doses to non-profit Europe, and reaching agreements with global non-profit organizations to distribute their injection to countries of low and middle income.
