Antibody treatment cuts coronavirus infection risk by 80% among care home residents, small study suggests

An antibody treatment extracted from the blood of recovered coronavirus patients could help ward off infectious outbreaks at care homes, research suggests.

Care homes were flagged as viral hotspots early in the pandemic, prompting their residents and staff to be first priority for the UK’s much-awaited vaccines.

The three approved jabs in the UK are known to cut the risk of coronavirus complications, however, it is unclear if they stem transmission of the infection.

With no vaccine being 100% effective and many elderly patients not well enough to receive them, scientists from the pharmaceutical company Eli Lilly tested the antibody bamlanivimab on 299 care home residents and 666 members of staff in the US.

Results suggest the residents who had the treatment were up to 80% less likely to catch the coronavirus over the next eight weeks, compared to those in the same care home given a placebo.

Among the residents, four COVID-related deaths occurred, all of which were in the placebo group.

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Bamlanivimab has received emergency use authorisation for the treatment of mild to moderate COVID-19, the disease caused by the coronavirus, by the US Food and Drug Administration.

The immune-fighting antibody blocks the coronavirus’ spike protein from attaching to a cell’s receptor, “thus neutralising” the pathogen.

The results are yet to be published in a peer-reviewed journal, but appear on Eli Lilly’s website.

“We are exceptionally pleased with these positive results, which showed bamlanivimab was able to help prevent COVID-19, substantially reducing symptomatic disease among nursing home residents, some of the most vulnerable members of our society,” said Dr Daniel Skovronsky, Eli Lilly's chief scientific officer.

“These data provide important additional clinical evidence regarding the use of bamlanivimab to fight COVID-19 and strengthen our conviction monoclonal antibodies such as bamlanivimab can play a critical role in turning the tide of this pandemic.

“We’re glad bamlanivimab is already available as a treatment for patients at high risk for progressing to severe COVID-19 illness or hospitalisation, including those in nursing homes, and look forward to working with regulators to explore expanding the emergency use authorisation to prevent the spread of COVID-19 in these facilities.”

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Bamlanivimab is not authorised for patients hospitalised with COVID-19 or those who require oxygen as a result of their complications. Previous studies have suggested it is ineffective among these critically-ill patients.

“Monoclonal antibodies, such as bamlanivimab, may be associated with worse clinical outcomes when administered to hospitalised patients requiring high flow oxygen or mechanical ventilation with COVID-19,” wrote the scientists.

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All 965 care home residents and staff tested negative for the coronavirus at the start of the study.

Overall, those who received bamlanivimab were 57% less likely to have developed “symptomatic COVID-19” over the next eight weeks.

Among the residents specifically, the risk of “contracting COVID-19” was reduced by 80%, the results show.

Sixteen deaths occurred during the trial, including those unrelated to the coronavirus.

“There were no COVID-19 attributed deaths in the bamlanivimab arm,” wrote the scientists.

No care home workers died of any cause.

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“The results of this innovative study further support the belief that bamlanivimab, and potentially other monoclonal antibodies, can reduce symptoms and may even prevent COVID-19,” said study author Dr Myron Cohen, from the University of North Carolina.

“The antiviral activity seen with bamlanivimab treatment emphasises the importance of early intervention to help counter the devastating impact the virus has had in this vulnerable population and other high-risk patients.”

When it comes to safety, “at least 1%” of those on bamlanivimab or the placebo endured side effects, with the most common being diarrhoea, nausea and dizziness.

The ongoing study will continue to evaluate bamlanivimab as a standalone treatment and alongside another antibody at care homes, enrolling up to 5,000 residents and staff.

‘Very encouraging’

Speaking of the results, Dr Andrew Garrett from the clinical research organisation Icon said: “There appears to be no safety concerns at this stage, and the number of COVID-19 attributed resident deaths, although small, were all in the placebo groups.

“These data are very encouraging therefore.

“Prevention of symptomatic infection is currently focused on vaccine deployment, although there may also be an important role for preventative treatments in those known to be exposed to the virus.

“These positive results are to be welcomed and have the potential to extend the use of bamlanivimab and support the fight against [the coronavirus].”

Other experts were similarly optimistic, but pointed out the relatively small and short trial had some shortcomings.

“As the recipients were receiving only passive antibodies, the level of which declines over time (as opposed to having a primed immune system [via vaccination] with potentially very long term immunity), it is not clear how long this protection would last for,” said Dr Peter English, editor of Vaccines in Practice.

“The press release doesn’t mention the cost of the treatment.

“My guess would be a dose of bamlanivimab will be a lot more expensive, and provide a shorter duration of protection, than vaccine.

“So it is not clear what the market for bamlanivimab is or will be. It may well have a place in prophylaxis in care homes, where residents are at particularly high risk, following exposure.”

The bamlanivimab participants received 4,200mg of the antibody in total, administered as 700mg injections.

Dr Kovilen Sawmynaden from the charity LifeArc believes the therapy may be useful in those who are “immunocompromised” or “allergic to vaccine components”.

As a precautionary measure, the UK’s vaccine regulator has said anyone with a “history of significant allergic reactions” should bypass the Pfizer-BioNTech coronavirus jab.

“[They] now have an alternative source of protection,” said Dr Sawmynaden.

Whether the treatment works against emerging variants of the coronavirus is another question.

“While this would be extremely disappointing, today’s findings prove this class of treatments remain an important avenue to pursue,” said Dr Nick Cammack, from the Wellcome Trust.

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