Those who received the Pfizer vaccine have fewer neutralising antibodies to protect against the Delta variant than other strains.
The Francis Crick Institute and the National Institute for Health Research conducted a study comparing levels of antibodies against each variant after one and two doses of the Pfizer vaccine.
Pfizer provides lower levels of neutralising antibodies against Delta variant
Results found that Pfizer vaccine receivers with two doses had almost five times fewer antibodies against the Delta variant than the original strain. The level of antibodies fell even further after just one dose.
After a single dose of thePfizer vaccine, 79% of receivers had adequate levels of antibodies targeting the original strain, 50% of those vaccinated had sufficient protection against the Alpha variant and 32% for the delta variant.
The study suggested that these antibody levels reduced with both old age and time, providing further evidence in favour of booster vaccines as well as reducing the delay between vaccinations.
Emma Wall, UCLH Infectious Diseases consultant and senior clinical research fellow for the Legacy study, explained: ‘Our study is designed to be responsive to shifts in the pandemic so that we can quickly provide evidence on changing risk and protection.’
The most important thing is to ensure that vaccine protection remains high enough to keep as many people out of hospital as possible. And 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.
Researchers have now submitted the study to the Genotype-to-Phenotype National Virology Consortium (G2P-UK), the New and Emerging Respiratory Virus Threats Advisory Group (Nervtag) and the Joint Committee on Vaccination and Immunisation (JCVI).
While studies such as these are needed to determine how to improve the COVID vaccines, levels of neutralising antibodies aren’t the only factors contributing to vaccine efficacy. And, even with lower neutralising antibodies, the Pfizer vaccine can still offer sufficient protection against the Delta variant.
Delta variant becomes the dominant strain in the UK
Public Health England (PHE) has announced thatthe Delta variant, previously known as the Indian variant, is now the dominant strain in the UK, taking over from the Alpha strain.
The PHE warned that a total of 12,431 cases of the Delta variant have now been confirmed in the UK up to June 2nd, a 79% increase from last week’s figure of 6,959.
There is also early evidence to suggest that the variant could lead to a ‘significantly increased risk of hospitalisation’ compared to the Alpha strain. This week, 278 people attended A&E with the Delta strain, 94 of those who were admitted to the hospital. The PHE revealed that most hospitalisations associated with the variant were people who had not had their vaccinations.