I got the Oxford-AstraZeneca COVID-19 vaccine Monday. I felt like I’d been hit by a truck for about 24 hours. But that was good. It meant my immune system was priming for battle, creating antibodies. And a day on the couch wasn’t so bad. Admittedly, I hesitated before booking the appointment. I wanted the A-list vaccine, the Pfizer-BioNTech shot, or at least Moderna, both of which appear to offer more protection with fewer reports of rare blood clots. But I had it wrong. The AZ vaccine is 62 per cent effective, compared to 95 per cent for Pfizer and 94 per cent for Moderna. But those numbers are deceiving. There’s more to it.