Friday, November 19, 2021

Better than a vaccine? AstraZeneca's preventative antibody drug slashes risk of falling ill with Covid by 83% and protection remains high after six months

An antibody drug developed by AstraZeneca cuts the risk of falling ill with Covid by more than 80 per cent, according to trial data which suggests it could offer longer-lasting immunity than the drug giant's jab.

The cocktail, which is equally effective when given as a preventative or a treatment, offers hope to elderly and vulnerable people who respond less well to vaccines.

AstraZeneca today published results from a six-month study of its Evusheld therapy, delivered as two injections at the same time.

A single course offered 83 per cent protection against symptomatic Covid after six months in unvaccinated vulnerable people. This is much higher than current vaccines, which are given as two doses and wane significantly within months.

AstraZeneca's own jab falls to just 40 per cent protection against symptoms at six months, and Pfizer and Moderna's drop to around 60 per cent.

The phase III study of Evusheld tested the cocktail on people with medical problems or conditions which put them at risk of not responding to vaccines.

Patients undergoing chemotherapy, which reduces the effectiveness of the body's immune system, or taking immunosuppressive drugs following an organ transplant are among those who don't always get the full protection from jabs.

In a separate study, which gave the cocktail to people after they caught Covid, it was shown to reduce the risk of severe illness by 88 per cent. Experts hope it will protect against hospitalisations and deaths for up to 18 months.

Britain is believed to have a million doses of Evusheld on order. But it is unclear how much the therapy will cost.

The US has invested £350million in supporting the research and manufacturing of the drug and has secured 100,000 doses, with the option to purchase up to 1m.

Results from the latest trial, which involved 5,200 participants, showed those who received the antibody were 83 per cent less likely to develop Covid symptoms than people who got a placebo.

Three quarters of the trial participants had a health condition which put them at high risk for severe a Covid infection if they were to become infected.

There were no deaths or severe cases of the virus in the cohort which got Evusheld, compared to two deaths and five severe Covid cases in the placebo group.

All participants were unvaccinated. They will be followed for 15 months to explore how long protection might last.

AZD7442 is made from two long acting antibodies, tixagevimab and cilgavimab.

These antibodies have been developed from B-cells donated by patients who recovered from a Covid infection.

B-cells are a type of white blood cell forming part of the body's immune system and generate antibodies.

Antibodies are a type of protein found in blood which binds to and neutralises foreign substances like bacteria and viruses preventing them from harming healthy cells.

However, after an infection has passed, the level of antibodies in the body eventually decreases.

So in AZD7442, scientists modified the two antibodies to last longer than conventional ones.

This is what gives the treatment the long-lasting protection of up to 12 months according to Astrazeneca.

Evusheld, a monoclonal antibody therapy also called AZD7442, contains two types of lab-made antibodies, and is given to patients via an injection into the arm, similar to some vaccines.

It is made by extracting the proteins from patients who have recovered from the virus, and then manipulating them in a lab to make them last longer than natural antibodies.

They bind to the virus' spike protein — which it uses to invade cells — to stop an infection, or to prevent the virus from multiplying when it does infect.

Antibodies are created by the immune system in response to the virus, either through vaccination or natural infection, in order to help the body fight if off in the future.

The current vaccines train a person's body to recognise Covid, but the immune system still needs to produce its own antibodies. The latest therapy skips that process, making the antibodies readily available.

In some immunosupressed people, their immune systems are so weak that even after vaccination, their body struggles to mount a response. AstraZeneca said the drug is primarily meant to help these patients and other at-risk individuals.

But at some point a wider group could benefit, it said, such as military personnel on tours of duty or cruise ship passengers.

The company also released an analysis of a separate trial of Evusheld, showing the antibody treatment led to better outcomes for people who caught the virus.

A trial of 903 people, 90 per cent of which were classified as being at high risk due to them having underlying conditions, who caught Covid showed those who were given Evusheld three days after symptoms started had a 88 per cent reduced chance of developing severe Covid or dying from the virus compared to people who got a placebo.

Professor Hugh Montgomery, an intensive care specialist based at University College London and lead researcher on the trial, said: 'These compelling results give me confidence that this long-acting antibody combination can provide my vulnerable patients with the long-lasting protection they urgently need to finally return to their everyday lives.

'Importantly, six months of protection was maintained despite the surge of the Delta variant among these high-risk participants who may not respond adequately to vaccination.'

AstraZeneca estimates 2 per cent of the global population has a condition meaning they are at risk of not being fully protected by a Covid vaccine.

The company's executive vice president Mene Pangalos said: 'These new data add to the growing body of evidence supporting AZD7442’s potential to make a significant difference in the prevention and treatment of Covid.

'We are progressing regulatory filings around the world and look forward to providing an important new option against SARS-CoV-2 as quickly as possible.'

Professor Penny Ward, an expert in pharmaceutical medicine at Kings College London, welcomed the results of both trials but added they needed to stand up to independent analysis. 'Regrettably neither study has been published in full and thus our ability to assess these data is limited,' she said.

'AZD are encouraged to publish the complete trial data and detailed results as rapidly as possible to enable prescribers to understand how best to use the product in practice.'

Professor Ward said, if the results are confirmed, AZD7442 could potentially become a key part of protecting immunocompromised Britons from Covid. 'This antibody cocktail is, uniquely, capable of offering long lasting protection from COVID to patients that are immunosuppressed and may not have responded effectively to vaccination,' she said.

'If may yet come to be considered an important adjunctive treatment for cancer patients and others needing immune-suppressing therapy for other diseases.' 'Let us hope a good supply of this product has been secured for use in the UK.'

AstraZeneca has already asked the US for emergency use authorisation for AZD7442 as preventative treatment for Covid.

While the company has not confirmed if it was seeking similar approval to use it in the UK it has stated it is 'discussing' trial data with health authorities.

It is unknown how much a dose of AZD7442 will cost if the drug is approved for use, but AstraZeneca famously sacrificed billions in profits by only selling its Covid vaccine at-cost.

That decision was hailed by the World Health Organization which called the affordable jab a 'vaccine for the world'.

AstraZeneca became a household name in 2020 due to its work with Oxford University in developing one of the the four Covid vaccines currently approved for use in the UK.

By the end of September there have been about 50million Oxford/AstraZeneca jabs administered in the UK, comprising of both first and second doses of the vaccine.

A number of drugs aimed at helping people infected with Covid recover have been found to help patients since pandemic ripped across the world in 2020.

One of these is dexamethasone, a steroid, found to cut the risk of death in severely infected Covid patients by 35 per cent, a made by UK scientists.

Another is Ronapreve, which like AZD7442 has been developed from the antibodies of recovered Covid patients.

The drug, made by Regeneron, was found to slash the risk of death or hospitalisation in people with severe health conditions by 70 per cent.

Ronapreve was approved for use in the UK on August 20 but NHS medics have struggled to get supplies of the drug for their patients despite it being available in the US since November.


Booster shots needed for some travellers

One of Australia’s leading vaccine experts argues Covid-19 booster shots should not be mandatory - but some international travellers will need to get them.

Aussie travellers are being warned they may need Covid-19 booster jabs in order to get into a growing list of countries that includes Austria, Croatia, Switzerland, Vietnam and Israel.

But while Covid-19 booster shots should be “strongly recommended” for Australians flying overseas, they should not be made mandatory here, according to one of the country’s leading vaccine experts.

University of Sydney Professor Robert Booy said mandating a third jab was “not palatable to the public, not practical, and not needed – you get substantial protection from two doses”.

There had “already been enough opposition to mandating the first two doses,” he said.

But Australians heading overseas should talk to their GPs, and a third jab was “strongly recommended,” particularly if they were going to areas with bad outbreaks such as Austria and Germany, Prof Booy said.

With studies showing most Covid-19 vaccines declining in efficacy over time, a growing cohort of countries is adopting expiry dates for their equivalent of our vaccine passports. This could mean if an Australian traveller’s second jab is outside the expiry period, they will need to get a third jab to enter the country.

For incoming tourists, Israel insists upon a jab within the preceding six months, while Austria, Croatia, Switzerland and Vietnam have opted for 12 months.

From mid December, France will require those aged over 65 to have had a booster shot in order to get into public venues, while in the UK, Prime Minister Boris Johnson has specifically mentioned booster shots when discussing future international travel arrangements.

Asked on the Insiders program on Sunday about the Morrison government’s position on boosters for international travellers, Health Minister Greg Hunt said they were recommended but not compulsory.

“The advice at this stage of Professor Murphy’s Scientific and Technical Advisory Group is that you’re regarded as fully vaccinated with two doses,” Mr Hunt said.

“Everything is always under review, but there’s no plan to change that requirement at this stage. But as we’ve done throughout, we’ll continue to follow the medical advice.”

Prof Booy said there was some suggestion it might be a better long-term strategy for fully vaccinated people to forego a booster shot and eventually get the virus. This would increase their “mucosal protection” – but studies on this were still ongoing. “We’ll have a lot more clarity on that in six months,” he said.

Booster shots have been offered to immunocompromised Australians since October 11, and all adults since November 8.

As of Wednesday, 298,841 Australians had received a third dose of a Covid-19 vaccine.




No comments: