People fully vaccinated with the Pfizer-BioNTech vaccine are likely to have more than five times lower levels of neutralising antibodies against the Delta variant first identified in India compared to the original strain, said a research published in Lancet journal. The research holds significance for India as the country plans to include Pfizer covid-19 jab in its vaccination program. B.1.617.2, prevalent in India, has already spread to over 45 countries.
The researchers tested the ability of antibodies to block entry of the virus into cells, so called ‘neutralising antibodies’, against five different variants of SARS-CoV-2. The study analysed antibodies in the blood of 250 healthy people who received either one or two doses of the Pfizer-BioNTech Covid-19 vaccine, up to three months after their first dose. They were tested against five different variants –SARS-CoV-2, the original strain first discovered in Wuhan, China; the dominant strain in Europe during the first wave in April 2020 (D614G); B.1.1.7, the variant first discovered in Kent, UK (Alpha); B.1.351, the variant first discovered in South Africa (Beta) and B.1.617.2, the newest variant of concern, first discovered in India (Delta).
The reserach supports current plans in the UK to reduce the dose gap between vaccines since they found that after just one dose of the Pfizer-BioNTech vaccine, people are less likely to antibody levels against Delta variant. After a single dose of Pfizer-BioNTech, 79 per cent of people had a quantifiable neutralising antibody response against the original strain, but this fell to 50 per cent for Alpha variant (B117), 32 per cent for Delta variant (B16172) and 25 per cent for Beta variant (B1351), showed the study, published as a Research letter in The Lancet on Thursday.
The results also show that levels of these antibodies are lower with increasing age and that levels decline over time, while no correlation was observed for sex or body mass index. More work is underway to test neutralising antibodies against these same variants in people who have been vaccinated with the Oxford/AstraZeneca vaccine.
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“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,” Emma Wall, UCLH Infectious Diseases consultant and Senior Clinical Research Fellow for the Legacy study, said.
(with PTI inputs)
