I think with the ones offered here in the States that are two-dose (Moderna and Pfizer), perhaps it's not as strong on the first dose. I certainly wouldn't ever recommend only getting one. I think the fact people build more of a reaction to the second dose and usually never the first dose is a good sign that the 2nd dose is the one that does the heavy lifting. 95 percent effectiveness is a great metric for Moderna, and that's why I chose that over Pfizer, which last time I checked was 94.5. That's only a .5 percent difference but I felt like with my health I need all the help I can get. Still, they are very comparable. I would have gladly taken the Pfizer if it was between it and J&J. However, I wouldn't have taken J&J's vaccine unless it was the only option here and that it was confirmed to be the only vaccine available going forward at least for the short term. I'm definitely in the "get both doses of the two-dose system" camp for vaccines if you can do it. However if it's one dose or bust, obviously take the one dose. I just worry it's not enough for some.

For most healthy people, the effectiveness of the J&J here in the States is enough to keep you out of the ICU on a vent and keep you protected. If you are healthy, you might get away with no signs or only get very very mild cold-like symptoms if you've been vaccinated with J&J. However, the at risk crowd really needs more effectiveness IMO. It might keep them from dying, but they could still end up very very sick with COVID-19. Of course, if you can only get a one-dose vaccine (and it gets reopened in the US), is it better than nothing absolutely. But I think if at all possible, opt for Moderna first, Pfizer second, and J&J as a last resort. I realize that what I'm saying only applies to those of us in the US and those with multiple clinics. Hopefully a two-dose system will make it's way to other countries soon as I really feel it is the best way to go for the best protection.

I hear Moderna is working on a booster for the variants. Moderna and Pfizer use mRNA methods which can smartly pick up on similarities between the variants and the original, so there will be some degree of coverage against the variants. How much we do not know yet, but it's believed to give some level of protection on the variants. I'll gladly take a Moderna booster (likely one dose) to offer the best protection. The J&J and AZ shots using adenovirus are built to detect the original virus and not pick up on small changes.