The highly infectious Delta variant, also known as the India variant, appears to have stalled efforts to lift all lockdown measures on June 21.
Adam Kurcharski, a mathematician and epidemiologist at the London School of Hygiene and Tropical Medicine, has pulled together this useful Twitter thread to help understand the much-cited race between vaccines and the variant.
“Despite relatively high vaccination rates compared to other countries, cases are growing and in many areas R is now above 1.5. Remember, immunity is already ‘priced in’ to this number – without vaccination and the social distancing still in place, R would be *much* higher,” he writes.
“If R is 1.5 and contacts/control remain the same, then we’d need remaining part of the population who could potentially spread COVID to shrink by at least 33% before R drops below 1 & epidemic peaks. This would require additional immunity, either from infections or vaccines.
“If contacts were to increase and, say, R increased to 2.5, then we’d need at least 60% reduction in size of remaining group who could potentially spread infection. Again, these calculations already account for vaccination to date – and still rather far from getting R below 1.”
You can find Dr Kurcharski’s full thread below, it’s well worth a read:
