Viruses are invisible, pitiless, ferocious, proven mass killers. The 1918 flu epidemic dispatched over 20 million people. Another such epidemic is expected before too long, and because communications have improved so much, it could be much more devastating. Yet Contagion is far less likely to be eliciting shrieks at your local multiplex than Paranormal Activity 3.
On the face of it, this constitutes a malfunction of humanity’s self-defence mechanism. Of course, when our instincts were taking shape we weren’t to know we should be worrying about pathogens rather than sabre-toothed tigers. Yet we’ve learned to frighten ourselves with plenty of new bugaboos, from terrorists to paedophiles, which don’t begin to match the threat we face from flu.