Well done for making it this far! Now we’ve covered how our amazing immune system works, let's look at the topic of “Herd immunity,” a term being thrown around on the regular at the moment by those in the know and those in the hysteria. I’m going to keep it simple and try to explain how it works. It describes a phenomenon when at-risk individuals are protected from infection as immune individuals surround them. This minimises the spread of infection. Immunity can have been gained via two ways, vaccination or infection. The term is usually used when talking about vaccines but the same principle applies. If a large number of the population is vaccinated or infected, and have thus created an adaptive immune response, created antibodies and therefore memory, they are protected from the disease. If they cannot get the disease, they cannot pass it on. 
Therefore, those that are not immune but who are surrounded by those that are, will still be protected. The flu vaccine is a prime example of this. I have my flu jab annually working at the hospital. That’s not for me. If I got the Flu I would be absolutely fine after a few days in bed. It’s for my vulnerable patients who have not been able to get the vaccination that year. If I can’t get infected, I can’t infect them, and neither can any of my colleagues who have also had their jab. We are providing herd immunity. Of course the Flu jab is never 100% perfect as strains are unpredictable but we at least have a fighting chance. If vaccination is not an option, the only other way to develop herd immunity is if the majority of the population actually fight off the infection and develop a natural immunity, i.e. they have to get sick and recover. The caveat to this is that infection does not guarantee that immunity follows, especially if the pathogen mutates and changes its antigen to avoid detection by our immune systems – cheeky hey!? If you have any questions on COVID-19 and/or our immune system, send them over to me on my Instagram @drsteph_scrubsvsshreds and I will do my very best. Dr Stephanie Hill
BSc, MBBS
