People most vulnerable to Covid-19 could require a booster of the BioNTech/Pfizer vaccine later this year, according to scientists who said the shot elicited a lower antibody response against the Delta variant first identified in India.
A study by researchers at the Francis Crick Institute and UCLH Biomedical Research Centre found that levels of neutralising antibodies in recipients of two shots of the vaccine were, on average, more than five times lower against the Delta variant than the original strain that emerged in Wuhan, China.
In a research letter published in the medical journal The Lancet, the scientists said that the results showed older people were the most affected and that their antibody levels declined over time.
Emma Wall, an infectious diseases consultant at UCLH, said “the most important thing” was to ensure the vaccines keep as many people as possible out of hospital.
“Our results suggest that the best way to do this is to quickly deliver second doses and provide boosters to those whose immunity may not be high enough against these new variants,” she added.
After only one dose of the BioNTech/Pfizer vaccine, 32 per cent of people showed a quantifiable antibody response against the Delta variant, the study found. In contrast about 79 per cent of people had a quantifiable antibody response against the original strain of coronavirus after their first jab.
Only about 25 per cent showed a response against the Beta variant, which first emerged in South Africa. It is not known exactly what level of antibodies is required to protect against disease.
Eleanor Riley, professor of immunology and infectious disease at the University of Edinburgh, said the data suggested that vaccines may offer “somewhat less protection against infection with the Delta variant”.
But Riley cautioned that the antibody response was not the only factor that dictated the effectiveness of an inoculation. “These data cannot tell us whether the vaccine will be any less effective at preventing severe disease, hospitalisation and death; we need to wait for the actual data on these outcomes,” she said.
“There are reasons to be optimistic on this score, as other immune responses — such as T cells — also contribute to protection against severe disease and these may be less affected by the mutations that affect antibody neutralisation.”
A study by Public Health England last month of the real world impact of the vaccines, found that two doses of the BioNTech/Pfizer shot was slightly less effective against the Delta variant, showing 88 per cent efficacy, compared with 93 per cent against the Alpha strain first identified in Kent. The Oxford/AstraZeneca vaccine was also less effective, that study found, with efficacy falling from 66 per cent for the Alpha variant to 60 per cent for Delta.
Pfizer said that it had not seen the Francis Crick and UCLH study.
Also on Thursday, Public Health England warned that early evidence suggested that “there may be an increased risk of hospitalisation” with disease caused by the Delta variant when compared with the Alpha variant, first identified in the UK. It cautioned, however, that more data was needed to have more confidence in the finding.
The public health agency said that Delta had overtaken the Alpha variant as the dominant Sars-Cov-2 variant in the country. It added that 278 people had attended A&E this week, resulting in 94 overnight admissions. This marks a slight uptick compared with last week, when 201 attended emergency services and 43 were admitted, it said.
The agency stressed that “the majority of these [cases] had not been vaccinated”. Among those admitted to hospital overnight, 66 per cent had not been vaccinated at all, and only 5 per cent had received both doses, according to PHE documents. The health body urged continued caution, saying that it was “absolutely crucial” that people played their part in preventing the spread of contagion.
The Link LonkJune 04, 2021 at 05:31AM
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Vulnerable people may need vaccine boosters this year, scientists say - Financial Times
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