Below is a very good video from Vox, explaining vaccine efficacy for Covid-19. The video shows how the efficacy value is certainly useful but it’s far from being the final say when deciding the effectiveness of a particular vaccine. This is because the efficacy value is highly dependent on when the clinical trial took place, and the incidence and strain of Covid-19 present at that time. If the trial took place when there was a high incidence of the disease, this will skew the values negatively for that vaccine, compared to a time when the virus incidence was low, or when a less infection strain was present. A more important value for a vaccine is not its efficacy, but how likely it will prevent serious illness, as the video explains.
Before I add the video link, I do need to point out an important fact with these vaccines. To my knowledge, no one has talked about how long the vaccines gives immunity to Covid-19. This is important because our immunes systems are notorious for losing immunity to coronaviruses over time, due the nature of coronaviruses. This is one reason why people can get one cold after another. Because the vaccines have been developed and distributed at such speed, this key factor has not been tested. We therefore face the possibility of having to vaccinate everyone every two months, roughly the time beyond which the immune system forgets its coronavirus immunity. That would be a huge, continual burden on our health services.
I can see three scenarios emerging with regard to Covid-19 vaccines; one, where regular national vaccinations do occur, at great national expense (and profit for biotech firms). The second is where most people simply hope they don’t get it, while the well-off minority few do regular vaccinations. The third scenario is where the virus evolves into a more harmless form and herd immunity, helped by mass-vaccination, suppresses its spread until it dies out. Fingers crossed, we’ll get the third version.
Anyway, here’s the video:
While we’re on the subject, here’s a another good video from Vox, explaining how the different vaccines work: