Astra counts the cost of its Covid-19 vaccine

The link between Astrazeneca’s vaccine and blood clots strengthens, but forecasts show that it was never expected to generate huge sales.

Policy and regulation

AZD1222 was never meant to be a big money-spinner for Astrazeneca: the company famously promised to provide its Covid-19 vaccine on a not-for-profit basis for the duration of the pandemic. And consensus sellside forecasts, compiled by Evaluate Pharma, show just how much bigger vaccines from Pfizer/Biontech and Moderna are expected to become.

Still, the UK company’s efforts took another blow yesterday with the admission by the EMA that there was a “possible link” between AZD1222 and the cases of unusual blood clots that have been causing consternation across Europe. The vaccine might not be costing Astra anything financially, but reputationally it has been loss making. 

Blood clot link

Yesterday’s EMA statement and press conference came around a month after the first reports of blood clots and deaths in people who had received AZD1222 – branded Vaxzevria in Europe – which led to several countries suspending its use (Astra’s Covid-19 vaccine woes deepen, March 11, 2021).

Since then, more details on these adverse events have emerged: the blood clots in question occurred alongside low levels of blood platelets, and were often seen in the brain, where they are known as cerebral venous sinus thromboses (CVSTs), or abdomen, where they are termed splanchnic vein thromboses.

The agency noted that, as of April 4, 169 cases of CVST and 53 cases of splanchnic vein thrombosis had been reported among 34 million people receiving the vaccine throughout Europe. So far, most of the cases have occurred among women aged under 60.

The agency recommended that these blood clots should be listed as “very rare” side effects of AZD1222, but concluded that the benefits of the vaccine still outweighed its risks.

This was the conclusion also broadly reached by the UK’s MHRA; however, that agency did concede that evidence for a link between the vaccine and blood clots was “firming up”. People in the UK under 30 will now be offered an alternative vaccine – not so much because of a slightly higher risk of blood clots in this population versus older groups, but because this population is less likely to develop severe Covid-19.

A similar consideration was behind the decision to pause a trial of AZD1222 in children earlier this week. Even if this study is restarted and the jab gets the go-ahead in young people, it is hard to see broad take-up here given that children rarely suffer seriously from Covid-19.

Even among adults, the potential impact on vaccine hesitancy is clear. And not just for AZD1222 – the latest developments could make people wary about getting any Covid-19 vaccine.

These other vaccines have so far escaped attention, although they too have been linked with some incidence of CVST, which the EMA spelled out yesterday: 35 cases among 54 million people vaccine with Pfizer/Biontech’s Comirnaty, and five among the four million receiving Moderna’s mRNA-1273.

A plausible explanation for the blood clots, according to the EMA, is an immune response to the virus; however, it is unclear how this might be triggered and why this issue might affect the Astra jab in particular.

A difference between AZD1222 and the other approved vaccines is that it uses a chimpanzee adenoviral vector, and an EMA report mooted this as a possible cause.

Johnson & Johnson’s JNJ-78436735, also uses an adenoviral vector, but a human one, adenovirus 26. The EMA yesterday said that three blood clots with low platelets had been reported to its pharmacovigilance database; the baseline number given was 4.5 million vaccinations, but this seems likely to be a worldwide figure.

Meanwhile, there was one case of CVST in J&J’s pivotal trial in a 25-year-old participant, and this briefly led to the study being halted, before the event was deemed unrelated to the vaccine.

Like Astra, J&J has pledged to make its vaccine available on a non-profit basis “for emergency pandemic use”. The group will hope that this is where the similarities end.

Share This Article