AZ vaccine study still on hold in the US, lawmakers hear majority of Americans remain susceptible to COVID-19

24-Sep-2020 - Last updated on 24-Sep-2020 at 16:03 GMT

AstraZeneca's phase 3 COVID-19 vaccine trial remains on hold in the US as the FDA probe into a patient illness in the UK trial that initiated the global pause continues, the US Department of Health and Human Services Secretary, Alex Azar, told US media yesterday [September 23].

A spokesperson for AstraZeneca told us: “Regulators in each individual country determine when trials can start and they do this in their own timeframe. Companies provide the information to the regulators to enable them to make this determination.

"On the current US trial status specifically, we are continuing to work with the FDA to facilitate review of the information and the agency will decide when the US trial can resume.”

He confirmed that the Phase 3 trials trial of its COVID-19 vaccine, AZD1222, have resumed in the UK, Brazil and South Africa.

AstraZeneca released its protocol for its Phase 3 trial last Saturday, following on from a similar move by Moderna and Pfizer; those companies published the design of the clinical trials for their vaccine candidates a few days ahead of their rival.

As with most clinical development, protocols are typically not shared publicly due to the importance of maintaining confidentiality and integrity of trials.

However, in a statement, AstraZeneca said that, given the unprecedented global impact of the COVID-19 coronavirus pandemic and the need for public information, it decided to publish the Phase 3 trial details.

“AstraZeneca continues to work with industry peers to ensure a consistent approach to sharing timely clinical trial information.”

Its goal is a vaccine with 50% effectiveness, according to the protocol. That is the threshold put in place by the US Food and Drug Administration (FDA) in its guidance for a COVID-19 vaccine.

Susceptibility rate to virus in the US

Meanwhile, Dr Robert Redfield, director of the US Centers for Disease Control and Prevention (CDC), told the US Senate Committee on Health, Education, Labor and Pensions (HELP) yesterday that more than 90% of the US population remains susceptible to the coronavirus.

He said the CDC is in the process of a very large study that will determine how widely COVID-19 has spread across the US.

Data on the rate of infection is critical given that epidemiologists believe infection generally conveys some immunity against the virus for at least a few months.

And according to information released today by the European Centre for Disease Control and Prevention (ECDC), the vulnerability of the population to infection remains high in most areas of Europe. It reported that the available data from seroprevalence studies suggest that the level of immunity in the population is less than 15% in most areas within the EU/EEA and the UK.