BROOKE GLADSTONE This is On the Media, I'm Brooke Gladstone.

BOB GARFIELD And I'm Bob Garfield. The world now has 11 vaccines of various kinds with a couple of more in the pipeline. Pfizer, Moderna and Johnson and Johnson are available stateside and another from Novavax may be here in May. Sussing out the differences between the vaccines has become a regular genre of TV spitballing.

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NEWS REPORT So how are Pfizer and Moderna similar? Let's take a look over here. So, both vaccines, you need two doses. They both have messenger RNA and both up to 95% effective, even with people with underlying conditions. [END CLIP]

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NEWS REPORT The Johnson and Johnson vaccine is a single dose. 85% effective in preventing severe disease. You guys 100% efficacy in preventing covid related hospitalizations and deaths. [END CLIP]

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NEWS REPORT You have the Pfizer at 95% effectiveness at preventing covid. Moderna 94%, and Johnson and Johnson, updated number there, 85%.

BOB GARFIELD And so people are doing what they do with cars and peanut butter and Tinder profiles; comparison shopping. But Helen Branswell, a senior writer at Stat News covering infectious diseases and global health says - resist the impulse. Helen, welcome to the show.

HELEN BRANSWELL Hi, thanks for having me.

BOB GARFIELD So comparison shopping is not necessarily the best approach. Why?

HELEN BRANSWELL Well, for one thing, most people won't really have a choice. You know, vaccine supplies are still really scarce right now. So your best chance of getting vaccinated is to take what is offered to you.

BOB GARFIELD The vaccines are either mRNA or viral vectored different mechanisms for implanting some genetic code into the subject. What's the difference?

HELEN BRANSWELL The mRNA vaccines, messenger RNA are brand new. There have never been vaccines of this type made before. Viral vector vaccines, there are few. For instance, the Ebola vaccine that was used in the recent large Ebola outbreak in the Democratic Republic of Congo was a viral vector vaccine. It's hard to compare the vaccine efficacy of the various vaccines at this point because the mRNA vaccines completed their trials early - before the variants, your listeners will have heard a lot of talk about – started to circulate. And so they definitely have sort of high numbers. Those are the ones that came in with sort of 94 and 95% efficacy, but they were playing on a different playing field than the vaccines that completed their trials more recently OR the ones that are still in trials.

BOB GARFIELD So if I understand you right, Moderna at 95% efficacy and Johnson and Johnson at 66% seems like a no brainer, but no, it's a brainer.

HELEN BRANSWELL Yeah, Moderna, which actually came in at 94%, their trial ended earlier before the variants started to circulate. So it's not clear it would still be 94% if it were being tested now. And the Moderna trial was looking for any infection and the Johnson and Johnson trial was looking for moderate to severe covid infection, the latter being really the more important thing, the thing that you really need these vaccines to do.

One of the things your listeners are probably already hearing is that public health people are sort of leaning into a different number when it comes to the Johnson and Johnson. The fact that, you know, it was 85 percent effective against severe disease.

BOB GARFIELD You began by mentioning that in the United States, most of us actually have no choice about what vaccine is available. Where I live, it's Moderna or nothing, but that's not necessarily true all over the world. I have a lot of friends and family in Serbia where they have the choice of Pfizer, AstraZeneca and Chinese and Russian vaccines. The Russian one, they call it Sputnik. And in Serbia, your vaccine is like a status symbol. Oh, Chinese, really? [SNICKERS] I got Pfizer. A conspicuous vaccine consumption.

HELEN BRANSWELL That's interesting to hear. While I said that most of us won't have a choice, that doesn't mean people won't try. I'm relatively certain that when people are looking online trying to book appointments, some of them may be looking to see what's being given at the mass vaccination sites where they're going. Right now, it's hard to book an appointment, but there are people who are more adept at it than others. There are people who have more time to spend at it than others. There are people who can get in the car and go a longer distance than others. And I think some of that is going on.

BOB GARFIELD In the United States. There will likely not just be, you know, sore arms and muscle pain, but political side effects, because, for instance, Johnson and Johnson just approved by the FDA, the lower reported efficacy numbers is easier to handle than other vaccines. It's easier to store and administer and will therefore likely be headed to more rural and poorer communities. But inevitably, with the lower reported efficacy, it will be deemed like, you know, second class treatment.

HELEN BRANSWELL Yeah, it's a real concern in public health circles that the very things that make this vaccine potentially a game changer are also going to lead to people assuming that, you know, the better vaccines are being saved for the more affluent. That people will start to see some of these other vaccines, not just the J&J, but AstraZeneca, if it is approved here, and in the Novavax vaccine, if it's approved here. These are vaccines that are easier to use because they don't require the ultra cold chain that the mRNA vaccines require. And in the case of the J&J, it's a one dose vaccine which makes it much easier to use. People have said this would be a great vaccine to use if you're trying to vaccinate people who are homeless, for instance. So you wouldn't need to worry about finding that person 21 or 28 days later to give them the second dose, but if people start to use the J&J vaccine uniquely in those kinds of settings, it could create the impression that there are classes of vaccines.

BOB GARFIELD How can it best be managed?

HELEN BRANSWELL You know, the experts I spoke to said one of the things that can be done to forestall this or deal with it is to be clear about why they're using the vaccines they're using in the different places that they're using them. It could well come down to there isn't supply of one, but there is supply of the other. And then, you know, explain this is going out now to these parts of the country, because that's what we have. Being clear with people about why these decisions are being made.

BOB GARFIELD Helen, thank you so much.

HELEN BRANSWELL Nice to talk to you.

BOB GARFIELD Helen Branswell is a senior writer at STAT News. Covering infectious diseases and global health. With the menu of vaccines continuing to expand, it is at times easier to focus only on the chaotic, bureaucratic maze of Americans trying to find someone, anyone who will jab them in the arm.

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