Half the equation is what Ed wrote about this morning, the unusual partnership between Johnson & Johnson and Merck to mass-produce J&J’s vaccine. J&J was supposed to deliver 100 million doses by the end of June. Sounds like Merck’s contribution is going to knock a month off of that estimate, which alone would cover a third or so of the U.S. population. The Johnson & Johnson vaccine is a single dose, remember, which means people can be fully immunized more rapidly than they can by Pfizer and Moderna. Granted, the data suggests that a single dose of the mRNA vaccines also provides strong immunity, but the Biden medical brain trust led by Fauci remains insistent that people get both doses, just as clinical subjects did in trials. If nothing else, rolling out the J&J shot will ease pressure on vaccine providers by reducing congestion in a system in which many people will be waiting for second appointments.