Even as the UK government is planning to give a third Covid vaccine shot to everyone above 50 years of age from next month, scientists confirm that the autumn booster dose will be an effective way to protect people from existing, and potentially future, variants of concern.
The team of experts at the University of Nottingham found that neutralising antibodies generated by a single dose of the Pfizer vaccine were less effective at neutralising key variants of concern, for example the beta (first identified in South Africa) variant.
However, the second dose, especially in those volunteers who had previously been infected with SARS-CoV-2, dramatically increased virus variant neutralising antibody responses (and therefore potential protection) to a level comparable to those seen for the original strain of SARS-CoV-2.
This suggests that an additional boost, even using vaccines containing the original strain of coronavirus, will increase protection against variants of concern, revealed the findings published in the journal Science Translational Medicine.
"We showed that the individuals with past infection produced more antibodies following each dose of vaccine than those who hadn't been exposed. We also showed that this increased antibody response was more effective against some of the variants of concern, such as the Beta and Gamma variants," said Professor Jonathan Ball from the School of Life Sciences at the University.
"In essence, natural infection has mimicked the effects of an additional vaccine dose, and our data clearly shows that this additional antigenic exposure produces an extra boost to the overall virus-killing antibody response that is more effective against variants of concern. Our results support the UK Government's plan to provide a booster jab in the autumn as an effective strategy in protecting people against these variants," he added.
UK Health Secretary Sajid Javid had said the government is awaiting advice from the Joint Committee on Vaccination and Immunisation (JCVI) on the roll out of the booster dose, which will be administered along with flu a jab, the Evening Standard reported on Wednesday.
The booster dose will be prioritised for people who received the Covid shots when the vaccination programmes were first rolled out last December, Javid said.
Meanwhile, the UK government on Tuesday also announced that 75 per cent of adults in the country have received both doses of a Covid-19 jab, while about 47 million people have received their first dose, the Financial Times reported. However, nearly 6 million adults -- roughly one in 10 of the over-18 population -- remain completely unvaccinated, official statistics showed.