AstraZeneca Resumes Phase 3 COVID-19 Vaccine Trial in UK

AstraZeneca announced on Saturday that it has resumed its phase 3 COVID-19 vaccine trial in the UK after pausing it last Tuesday due to a single “unexplained illness.”

The British drugmaker said that the Medicines and Healthcare Products Regulatory Authority (MHRA) determined that it was safe to resume the trial following an investigation by an independent committee in the UK. Further information about the patient was not disclosed, but the company said all trial investigators and participants will be updated with the information and the incident will be disclosed on global clinical registries.

The company shot down reports that AstraZeneca CEO Pascal Soriot had said the safety issue was confirmed to be symptoms from transverse myelitis, adding that he said there will be no conclusions until more tests are conducted (DID, Sept. 10). Vaccinations were on hold globally while independent safety committees and regulators around the world reviewed the safety data.

AstraZeneca said it will “work with health authorities around the world and be guided as to when other trials can resume.” The trial has not yet resumed at sites in the U.S.

AstraZeneca’s decision to pause the trial on Tuesday sent shockwaves as it is the only trial of a COVID-19 vaccine known to be put on hold. The decision was praised by National Institutes of Health Director Francis Collins, who said it serves as “exhibit A” for not compromising on the safety of a COVID-19 vaccine (DID, Sept. 10).

However, Soriot said on Thursday that the company expected to still submit its vaccine candidate for approval by the end of the year as long as the safety review allowed the trial to resume (DID, Sept. 11).

This was not the first time the trial was paused. The company said Wednesday that “there was a brief trial pause in July while a safety review took place after a volunteer was found to have an undiagnosed case of multiple sclerosis, which  the independent panel found that was unrelated to the vaccine” (DID, Sept. 10).

Also on Saturday, Pfizer and BioNTech announced that they submitted an amended protocol to the FDA to expand enrollment of their phase 3 COVID-19 vaccine trial to 44,000 participants, up from its initial target of 30,000.

The drugmakers said the expansion would provide additional safety and efficacy data and allow the companies to increase the diversity of the trial. The companies also plan to include adolescents as young as 16 years old and people with chronic, stable HIV, hepatitis B or hepatitis C.

The drugmakers said enrollment had been proceeding as planned and that they expect to hit the 30,000-participant mark this week. As of last Monday, the trial had enrolled 25,189 participants.

Data from the trial is still expected by the end of October. — Jordan Williams