AstraZeneca on Tuesday announced that it has paused the company's Phase 3 clinical trials for its coronavirus vaccine candidate to investigate a serious illness that has developed in a trial participant in the United Kingdom, as it's not clear whether the illness is linked to the experimental vaccine.
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US new coronavirus cases pass 6.3M, deaths approach 190K
The news comes as U.S. officials as of Wednesday morning reported a total of 6,345,700 cases of the novel coronavirus virus since the country's epidemic began—up from 6,317,200 cases reported as of Tuesday morning.
Growth in the number of new coronavirus cases reported daily in America appears to be leveling off, with the country's average daily number of newly reported cases falling from more than 70,000 in July to about 40,000 over the past week, according to Washington Post review of nationwide data reported as of Tuesday. However, experts are concerned that America's rate of new cases has plateaued at a high level, which means growth in new cases may spike again.
Data from the New York Times shows there are 13 states that have seen comparatively higher rates of coronavirus transmission, meaning they've had a daily average of at least 15 newly reported coronavirus cases per 100,000 people over the past week, where rates of newly reported cases are "staying high." Those states are Alabama, Arkansas, Illinois, Iowa, Kansas, Kentucky, Louisiana, Missouri, North Dakota, Oklahoma, South Carolina, South Dakota, and Tennessee.
Meanwhile, the Times' data shows that the daily averages of newly reported cases over the past seven days are "going down" in Georgia, Guam, and Mississippi, which had all been seeing comparatively higher rates of coronavirus transmission.
The Times' data also shows there are six states that have seen comparatively lower rates of coronavirus transmission, meaning they've had a daily average of fewer than 15 newly reported coronavirus cases per 100,000 people over the past week, but are now seeing those rates "going up." Those states are Delaware, Maryland, Nebraska, New Hampshire, Pennsylvania, and West Virginia.
In addition, the Times' data shows that Puerto Rico; the U.S. Virgin Islands; Washington, D.C.; and 29 states have had comparatively lower rates of new coronavirus cases over the past week, and those rates are "staying low." Those states are Alaska, Arizona, California, Colorado, Connecticut, Florida, Hawaii, Idaho, Indiana, Maine, Massachusetts, Michigan, Minnesota, Montana, Nevada, New Jersey, New Mexico, New York, North Carolina, Ohio, Oregon, Rhode Island, Texas, Utah, Vermont, Virginia, Washington, Wisconsin, and Wyoming.
U.S. officials as of Wednesday morning also had reported a total of 189,538 deaths linked to the coronavirus since the country's epidemic began—up from 189,076 deaths reported as of Tuesday morning.
According to the Times' data, Hawaii, Kansas, Missouri, and West Virginia saw their average daily numbers of newly reported deaths linked to the coronavirus rise over the past 14 days.
AstraZeneca pauses late-stage coronavirus vaccine trial
As the coronavirus continues to spread throughout the world, researchers are scrambling to develop a vaccine against the virus, with some companies already conducting late-stage trials on coronavirus vaccine candidates.
AstraZeneca, which is developing a vaccine candidate called AZD1222 with researchers from Oxford University, is one of the frontrunners in the race for creating a coronavirus vaccine, the Times reports. The company currently is conducting Phase 2/3 trials on AZD1222 in the United Kingdom and India and Phase 3 trials in the United States, Brazil, and South Africa.
AZD1222 uses chimpanzee adenovirus that researchers have modified to transmit coronavirus genes into human cells, which then triggers a protective immune response that could be reactivated if the novel coronavirus tries to infect a person. Adenoviruses are generally believed to be safe, but they can sometimes incite an immune response that is harmful to patients.
On Tuesday, AstraZeneca announced that it has suspended all of its Phase 3 clinical trials on AZD1222 to conduct a safety review to investigate a "potentially unexplained illness" in a trial participant.
AstraZeneca explained that participants in large clinical trials can sometimes become sick by chance, and not necessarily because of the experimental treatment they received, so unexpected illnesses "must be independently reviewed to check this carefully." As such, the company said the pause in Phase 3 trials is a "routine action which has to happen whenever there is a potentially unexplained illness in one of the trials, while it is investigated, ensuring we maintain the integrity of the trials."
AstraZeneca did not provide extensive details on the trial participant's condition. However, a person familiar with the situation who spoke to the Times on the condition of anonymity said the U.K. participant, who had been enrolled in a Phase 2/3 trial, was diagnosed with transverse myelitis, which is an inflammatory syndrome that affects the spinal cord and often is triggered by viral infections.
According to the Times, it remains unclear when the participant received the diagnosis and whether the participant's diagnosis is directly linked to AstraZeneca's coronavirus vaccine candidate.
What does the pause mean for coronavirus vaccine timing?
AstraZeneca said it is "working to expedite the review of the single event to minimize any potential impact on the trial timeline." The company added that it is "committed to the safety of [trial] participants and the highest standards of conduct in [its] trials."
According to the STAT News, it is unclear how long AstraZeneca's hold on its Phase 3 trials will last, but individuals familiar with the matter have said the report of the illness is affecting other vaccine trials led by AstraZeneca, as well as trials being led by other drugmakers. STAT News reports that one person familiar with the matter said researchers conducting other vaccine clinical trials are now trying to identify similar cases of illnesses by examining "databases reviewed by a so-called Data and Safety Monitoring Board."
"We will need more information but obviously this is concerning," Carlos del Rio, a vaccine expert at Emory University, wrote in a tweet posted Tuesday (Gearan/Weiner, Washington Post, 9/8; New York Times, 9/9; Robbins et al., STAT News, 9/8; Brennan, Politico, 9/8; Sullivan, The Hill, 9/8; New York Times, 9/9).