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Thursday, May 13, 2021

New research: In Covid survivors, single Pfizer dose boosts response against key strains

The findings looked at immune responses in UK healthcare workers at Barts and Royal Free hospitals following their first dose of the Pfizer/BioNTech vaccine.

By: Express News Service | New Delhi |
Updated: May 5, 2021 8:03:00 am
Pfizer vaccine, Coronavirus vaccine, Covid-19 vaccine, vaccine effective, Indian ExpressThe findings looked at immune responses in UK healthcare workers at Barts and Royal Free hospitals following their first dose of the Pfizer/BioNTech vaccine.

A single dose of vaccine boosts potent responses against SARS-CoV-2 coronavirus variants in those with previous Covid-19, a study has found. In those who have not previously been infected and have so far only received one dose of vaccine, the immune response to variants of concern may be insufficient.

The findings, published in the journal Science and led by researchers at Queen Mary University of London, Imperial College London and University College London, looked at immune responses in UK healthcare workers at Barts and Royal Free hospitals following their first dose of the Pfizer/BioNTech vaccine.

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They found that people who had previously had mild or asymptomatic infection had significantly enhanced protection against the UK and South Africa variants, after a single dose of the mRNA vaccine. In those without prior Covid-19, the immune response was less strong after a first dose, potentially leaving them at risk from variants.

Blood samples were analysed for the presence and levels of immunity against the original strain of SARS-CoV-2, as well as the UK (B.1.1.7) and South Africa (B.1.351) variants of concern. Along with antibodies, the researchers also focused on two types of white blood cell: B-cells, which ‘remember’ the virus; and T cells, which help B cell memory and recognise and destroy infected cells.

They found that after a first dose, prior infection was associated with a boosted T cell, B cell and neutralising antibody response, which could provide effective protection against SARS-CoV-2, as well as the UK and South Africa variants.

However, in people without previous SARS-CoV-2 infection, a single vaccine dose resulted in lower levels of neutralising antibodies against SARS-CoV-2 and the variants, potentially leaving them vulnerable to infection and highlighting the importance of the second vaccine dose.

The team looked at two variants of concern; however, they think it possible that the findings will apply to other variants in circulation, such as the Brazil (P.1) and India (B.1.617 and B.1.618) variants.

Source: Queen Mary University of London

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