COVID-19 vaccines this week, with fewer than 445,000 doses of Pfizer-BioNTech shots scheduled for delivery over the next seven days.Yet that seeming trickle is set to explode into a full-blown flood starting the week of March 22 as the companies dramatically ramp up their deliveries and other pharmaceutical firms start making good on their own promised shipments.The Public Health Agency says this coming week will be the last in which Canada will receive fewer than 1 million doses over a seven-day period.