Paediatric trial of AZ COVID jab 'halted as a precaution'


Oxford University has suspended a clinical trial of its AstraZeneca-partnered COVID-19 vaccine in children and adolescents while a possible link to rare cases of blood clotting is investigated by the UK drugs regulator. 

Around 300 volunteers have been enrolled into the trial, but investigators have decided to pause dosing with the Oxford/AZ vaccine while they wait for an update from the Medicines and Healthcare products Regulatory Agency (MHRA).

The university has stressed that no safety concerns have emerged among young people who have already been dosed in the study, and it says parents and children should continue to attend all scheduled visits.

The trial started in February with the aim of recruiting 300 subjects aged between six and 17 years, with 240 due to receive the AZ1222 vaccine – now called Vaxzevria – while 60 would get a control meningitis vaccine. Results were expected in the summer.

The MHRA, EMA and WHO are all due to publish an update on cases of the rare blood clot cerebral venous sinus thrombosis (CVST) among people taking the AZ vaccine later this week, but are all saying that dosing with the shot should continue uninterrupted for now.

One EMA official jumped the gun yesterday however, telling Italian newspaper il Messaggero in an interview there was a link between the AZ vaccine and CVST that would be announced shortly, possibly later today.

Marco Cavaleri, who heads the EMA's vaccines strategy group, reiterated that the EMA's advice remains that the AZ vaccine's benefits outstrip any risks.

The EMA's Pharmacovigilance Risk Assessment Committee (PRAC) is meeting all this week, and according to its agenda is reviewing safety signals for both Vaxzevria and the Janssen-Cilag one-shot coronavirus vaccine, which was cleared for emergency use in the EU last month.

The document says blood clotting cases for both the AZ and Janssen-Cilag jabs will be assessed, along with a possible signal of capillary leak syndrome with Vaxzevria.

In a statement posted after the newspaper article was published, the EMA insisted that the PRAC "has not yet reached a conclusion and the review is currently ongoing".

Sputnik V probe

It also emerged this week that the EMA is planning a separate investigation into the Russian Sputnik V vaccine, although that isn't looking at safety.

Rather, the regulator is concerned that clinical testing of the shot may have contravened ethical and scientific standards, according to a Financial Times article, citing people familiar with the EMA's approval process.

The probe stems from claims that military servicemen and state employees were pressured into taking part in the trial. The agency is in the midst of a review of Sputnik V to see if it can be granted emergency authorisation, but can’t give a green light if a trial has contravened good clinical practice (GCP) standards.

The Russian Direct Investment Fund (RDIF) promoting Sputnik V said that the vaccine has already been approved in dozens of countries around the world with no concerns about GCP. It has made repeated claims of bias against the shot in western nations.

Moderna rollout starts in Wales

Meanwhile, there was more good news for the UK's coronavirus vaccination programme today as it emerged that the first doses of the Moderna vaccine have been delivered to health authorities in Wales, with dosing due to start imminently.

It is the third COVID-19 vaccine to be made available in the UK after the Oxford/AZ and Pfizer/BioNTech jabs, and the delivery comes a little earlier than expected. The first doses will be administered at Carmarthen's Glangwili Hospital.

The arrival of the Moderna shot could go some way towards ameliorating an anticipated dip in supply of the AZ vaccine in the coming weeks.