The vaccines being administered to protect against COVID-19 are almost certainly less effective against preventing the transmission of the B1.617.2 variant first identified in India, a leading UK scientist who advises the country's vaccination programme said on 15 May.

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Professor Anthony Harnden, from the University of Oxford who is the deputy chair of the Joint Committee on Vaccination and Immunisation (JCVI), said it was important to approach the easing of lockdown in England with utmost caution as it remains unclear exactly how much more transmissible the variant detected in India is. But he reiterated that there is no evidence so far of increased severity of illness or that the particular mutation of the coronavirus evades the vaccine. The vaccines may be less effective against mild disease but we don't think they're less effective against severe disease. But in combination with being less effective against the mild disease, they're almost certainly less effective against transmission, Prof. Harnden told the BBC.

We don't know how much more transmissible it is yet. All the evidence so far suggests there is no evidence of increased severity of illness or that it evades the vaccine. So, at the moment, on the basis of the evidence we are doing the right thing, coolly, calmly continuing with Monday, but keeping everything under review, he said, in reference to the next stage in the easing of lockdown that begins in England from 17 May.

His comments follow UK Prime Minister Boris Johnson's Downing Street press conference, when he focussed on the important unknowns related to the B1.617.2 variant, which is believed to be largely behind India's devastating second wave of the COVID-19 pandemic. We believe this variant is more transmissible than the previous one in other words it passes more easily from person to person but we don't know by how much, said Johnson. I am told that if it's only marginally more transmissible, we can continue more or less as planned. But if the virus is significantly more transmissible, we are likely to face some hard choices. We are going to be learning a lot more in the coming days and weeks about that, he said, in an indication that a planned June 21 timeline for an end to all lockdown measures is likely to change.

He also pointed to the good news that so far there is no evidence to suggest the vaccines being administered by the National Health Service (NHS), which includes the Oxford/AstraZeneca vaccine being deployed in India as Covishield, will be less effective in protecting people against severe illness and hospitalisation. So I believe we should trust in our vaccines to protect the public whilst monitoring the situation very closely. Because the race between our vaccination programme and the virus may be about to become a great deal tighter, he said.