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Evusheld – does it work against Omicron?

6th Jun 2022 - Rachel Kahn

What is Evusheld?

Evusheld is made by the pharmaceutical company AstraZeneca and is designed to prevent Covid infections.

Evusheld is already available in countries like the United States, Canada, France, and Israel. It was approved for use in the UK by the Medicines and Healthcare Regulatory Authority (MHRA) in March 2022, but the Government has not yet purchased the drug, and so at the moment people with blood cancer in the UK are unable to get it.

Evusheld was created to treat the original strain of the coronavirus. In this blog, we talk about what the latest research is telling us about how effective this treatment is when it comes to Omicron, which is now the dominant variant in the UK.

Research in the lab

Initial studies looking at how effective Evusheld was at preventing Omicron infection were done in the lab. These studies give us an idea of how effective drugs like Evusheld are, but studies in people gives us more certainty. One lab study looked at the effectiveness of lots of different antibody-based treatments, including Evusheld. This study found that the antibodies that Evusheld is made up of (tixagevimab and cilgavimab)do still seem to work against Omicron, although it does not seem to be as effective as it was at destroying the original strain of the virus.

The dominant strain of coronavirus in the UK currently is an Omicron strain BA.2, making up 97% of cases and it was this strain that Evusheld was able to destroy in the study described above. But there are other different types of Omicron emerging so called “BA.4” and “BA.5” which all have slightly different mutations making them act in different ways. In the study above, Evusheld didn’t appear to work very well against BA.4 or BA.5 and so this is something that we will need to keep an eye on.

This is similar to some recent research carried out by the University of Oxford which showed that Evusheld was 8x less effective at destroying BA.4 and BA.5 compared to BA.2.

A similar study looked at the effectives of 19 different antibodies and 17 were shown to be ineffective at destroying Omicron. Thankfully, Evusheld did remain effective against this Covid strain.

Research in people with blood cancer

As some countries such as the US are already using Evusheld, there has been research looking at how well the treatment works at preventing the virus in people who received it.

One study looked at people with blood cancer specifically. Most of these people had non-Hodgkin lymphoma and almost half had had a stem cell transplant. Due to fears that the approved dosage of Evusheld might not work as effectively against Omicron, the authorisation changed to allow people to receive a double dose of the drug. This meant that in this study, 90% of people were given the standard dose of Evusheld and 10% were given a double dose.

The researchers took a blood sample from people who had received Evusheld one month after the infusion and looked at how well the antibodies worked at destroying Omicron. Unfortunately, only 36% of people had antibodies that could destroy Omicron (17/47), but 90% of people who had received a double dose had antibodies that could. Two of the people in the study got Covid but neither of them became so unwell that they needed hospital treatment.

The MHRA has also approved a double dose of the treatment for use, and so we hope it will be offered to people at this dose. This decision was based on studies done in the lab where Evusheld seemed to be less effective against Omicron than previous coronavirus strains. A double dose of the treatment is hoped to increase its effectiveness as it appeared to in the study above.

Research in people with other conditions

Another study that looked at how effective nine monoclonal antibodies were against the BA.2 variant of Omicron. They again took blood from people who had received Evusheld in the month prior and found that 66% of people did have antibodies that were able to destroy Omicron, which is higher than the study above. Only one person in this study had blood cancer – most others were immunocompromised due to other conditions or taking other medications.

Evusheld is made up of two antibodies: cilgavimab and tixagevimab. Interestingly, this study showed that cligavimab worked just as well at destroying Omicron on its own as it did in combination with tixagevimab, which suggests that effectiveness of tixagevimab is severely reduced against Omicron.

In this study, four people got Covid and one required treatment in hospital.

Evusheld has also been shown to remain effective in people who have had solid organ transplants. One study looked at 222 people who received Evusheld and 222 who had not. 1.8% of people who received Evusheld got Covid, compared to 4.7% in the group that hadn’t received it, showing that it is still working at preventing infections. In this study 60% had received the double dose of the drug, compared to 40% who had the standard dose.

Most of these studies show that, although not as effective as it once was, Evusheld still remains a useful treatment at preventing infection with Omicron. The research shows that while BA.2 remains the dominant variant, the utility of Evusheld should hold up, but this will have to be closely monitored, particularly as initial research shows that it isn’t as effective at destroying other types of variants.

We have shared all of this research with senior officials in Government and are continuing to ask them to set out their plans to buy the treatment to give protection to those most vulnerable and hope this happens imminently.

You can read more about what we know about Evusheld, and what it might mean for people with blood cancer here.

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