Obviously a 100% effectiveness would be ideal in an ideal world, but with vaccines, that is never the case. However, it seems that 90% is actually a lot better than what most experts had hoped for. Right now, regulators are saying that they are willing to approve a vaccine that is 50% effective, so for it to be 90% effective is actually rather impressive.
According to Dr Albert Bourla, the Pfizer chairman and CEO, “Today is a great day for science and humanity. The first set of results from our phase 3 Covid-19 vaccine trial provides the initial evidence of our vaccine’s ability to prevent Covid-19. We are reaching this critical milestone in our vaccine development program at a time when the world needs it most with infection rates setting new records, hospitals nearing over-capacity and economies struggling to reopen.”
That being said, the results are based on clinical trials so whether or not it will have the same results if and when it is released to the public remains to be seen, but for now, it certainly paints a hopeful future.