Why there’s still reason to hope for an effective Covid-19 vaccine

Sir – I believe I am immune to smallpox, diphtheria, whooping cough, tetanus and other diseases, as a result of vaccination.

I do not expect to have antibodies in my blood, as I have not been exposed to any of these infectious organisms recently. However, if I am, my longlived memory T cells, which preserve data on my immunity, will stimulate my B cells to produce specific antibodies. These will gradually disappear from my blood as they overcome the invader, but I will still be immune.

In light of this, it seems to me that the falling levels of antibodies observed in the recent Covid-19 study (report, October 27) reflect normal recovery from a viral illness – and do not necessarily mean that immunity has not been achieved. These results should be interpreted cautiously when considering the likely effectiveness of a vaccine.

Dr Diana Macfarlane FRCP Tunbridge Wells, Kent

Sir – While the results of the study on which you report may raise doubts about the efficacy of a Covid-19 vaccine, many suspect that a T cell response would be a better marker of immunity. In any case, the study may have a more useful effect.

The Government’s Plan A (repeated lockdowns until a vaccine arrives) is facing growing criticism. Now there is a plausible reason to switch to a Plan B. This would involve shielding the now well-known vulnerable groups and allowing everyone else to return to a more normal existence.

Coupled with rapid tests for the virus and local-authority input on tracing, it would allow us to address the appalling effects of current policy, which are arguably worse than those of the virus itself.

Professor R A Risdon

London SW13

Sir – It has been suggested that many will ignore the “rule of six” over Christmas. This assumes that travel will remain relatively unrestricted.

During the first lockdown, the very few cars on the road were immediately obvious to the authorities and could easily be stopped. I will not be surprised if the Government delivers a nasty present before Christmas to ensure compliance with its strictures. Keith Whittaker Newcastle-under-lyme, Staffordshire

Sir – As a lifelong Tory, I hate to get involved in Government-bashing, but there is a problem with its approach.

On several recent visits to France, we didn’t see one person without a mask where mandated. Now we are in Dubai where, at the entrance to every shop, restaurant and office, somebody will scan your temperature and ensure that you are wearing a mask. Unless the rules are properly enforced, there is no point in having them.

Michael West

Poole, Dorset

Sir – I wonder if my “Freedom Pass” will ever live up to its name again. Gael-anne Morgan

Surbiton, Surrey