From Jonathan Watson, London, UK
Could there be an alternative to a coronavirus vaccine to achieve herd immunity if we could come up with a test to predict who would be asymptomatic? Many people would probably fall into this category (5 September, p 7). They might have something in common other than their underlying good health that could be the basis of such a test.
If this were possible, then herd immunity might be achievable with deliberate asymptomatic infection rather than vaccination.
