We have certainly speeded up the process of developing a vaccine. According to the World Economic Forum it normally takes 10 years to develop a vaccine, whereas it looks as though we may be able to start the immunisation programme around 9 months after the declaration of a pandemic. That’s an incredible achievement, but I would be surprised if, with hindsight, a few more weeks could not have been shaved off safely.

There was a fascinating article in the British Medical Journal which looks into whether or not there was pre-existing immunity in the population. At school I learnt that there are red blood cells and white blood cells. Red blood cells carry oxygen around the body and white blood cells fight infection. But as Imperial College London explain there are two types of white blood cells, B cells and T cells. B cells produce antibodies which fight the infection. T cells can kill the cells which have been infected and can also support the B cells to make antibodies.

The majority of the testing to find out whether a person has the virus has been testing for antibodies. Unfortunately it’s only possible to detect them up to ten weeks after the infection whereas it has been found that people who had SARS still have excellent T cell protection 17 years after the infection.

A number of studies have found T cells responsive to Covid 19 in people that it is believed haven’t been exposed to Covid 19. This raises the question does past exposure to other Covid viruses (such as MERS, SARS and even the common cold) leave us with T cells able to fight Covid 19? As we don’t yet know the answer to that, we don’t know what level of herd immunity there is in the population. We have assumed that we started this war on Covid 19 from ground zero whereas we may not have. The science around herd immunity is also growing rapidly. The calculation of the Herd Immunity Threshold (HIT) which we have used since the 1970’s assumed that immunity was evenly distributed in the population and that members of the population mix at random. Scientists looking at those assumptions now, and factoring in the pre-existing immunity that T cells may provide, consider that the herd immunity threshold may be as low as 10% rather than the 60% which the reproduction rate of 2.5 would suggest.

Oxford University in collaboration with Stanford University have developed machine learning software that can identify subsets of immune cells which indicate whether a person with those cells would respond well to a vaccine. It may also be possible to boost those cells in people who are deficient. Oxford and Stanford have made the software freely available to all researchers.

In conclusion I feel hopeful that fighting this war on Covid 19 will make us much better prepared for the next pandemic. I also hope that governments around the world will realise how vital their investment in health services and universities are.