How will we know when vaccines need to be updated?
This is more complex. For flu there is a sophisticated global surveillance process in which new variants are spotted in advance and vaccines adjusted accordingly. This process is not yet in place for Sars-CoV-2.
Covid is not yet tracked well globally and may not move in a predictable seasonal pattern like flu. As a new virus, it may also mutate less predictably.
Another complexity is that vaccines will have to cover off more than one variant as they evolve, as well as existing strains. The more a vaccine is re-engineered, the more likely regulators will demand new safety trials.
Read more: From transmission to efficacy, the Oxford, Pfizer and other Covid vaccines compared
Will closing borders help stop the spread of the new variants?
Closing borders completely is never a good move for a trading nation. North Korea is really the only country to have done it.
On the other hand, good border checks and passenger testing and isolation policies like those operated from the outset by South Korea, Hong Kong and others in east Asia can limit the spread of new viruses. The trouble is they are resource intensive and require strong administrative competence and advance planning.
The Government is implementing an Australia and New Zealand-style hotel quarantine for travellers arriving in the UK from selected countries in order to prevent new variants being imported.
Critics warn it will only work if all foreign travel is covered and, even then, only if the Home Office can get the execution of the policy right. Others warn that once in place, such policies can be hard to wind down.
How far have the existing variants already spread?
The UK and South African variants have spread rapidly – the UK variant is now in more than 50 countries and the South African one has spread throughout the southern part of the continent.
The Brazil variant has been detected in travellers to South Korea and Japan but is not thought to have spread widely beyond its borders.
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