No longer “one and done,” but maybe “two and through”? The question should rather be whether Johnson & Johnson/Janssen should have considered its vaccine for COVID-19 a two-shot regimen all along. That question comes before the FDA today, after J&J submitted an application for emergency-use authorization for a booster shot. This follows two major studies demonstrating that a second shot provides nearly complete protection against COVID-19 and all the current variants:

Johnson & Johnson announced on Tuesday that it has asked the Food and Drug Administration (FDA) to grant emergency authorization for a booster shot of its COVID-19 vaccine for individuals aged 18 years and older.

In a statement, the company said it based its filing on the results of a late-stage clinical trial that found that a booster dose of its single-shot vaccine given 56 days after the first dose provided 94 percent protection against symptomatic COVID-19, and 100 percent protection against severe and critical disease at least 14 days after the second dose.

The CNBC crew muffs the data a bit here. In the first place, the Phase 3 trial efficacy for J&J was 72%, not 60%, and that data came against a broader range of variants than those faced by Pfizer or Moderna in their Phase 3 trials. Real-world data has shown a higher efficacy than the Phase 3 trials, although that may be a result of poor population testing in the US, where asymptomatic cases go almost entirely undetected. They are correct that J&J has proven more durable in real-world data too, but their measure — antibodies in the bloodstream — is not the correct metric. The real test of durable response is in the T- and B-cells of those inoculated, which is difficult to measure reliably. Those systems produce antibodies in response to exposure, and the body stops producing antibodies at some point afterward when they are no longer necessary.

Anyway, the point of this is that J&J recipients are probably fairly well protected at this point, but almost certainly not 94% against acute cases. Also, vaccines routinely need boosters anyway, so the real questions here are whether they are (a) safe and (b) provide enough of a boost to make it worthwhile. Two different studies have answered yes to both questions, especially the second. The inference on the effectiveness from a booster for the J&J shot is that it will be as effective as the mRNA shots but even longer lasting, perhaps more even than for three mRNA shots — although that may take years to determine.

Will the FDA approve a booster for J&J after dousing the expectations for green lights general-population boosters of Pfizer and Moderna? The New York Times curtain-raiser yesterday suggests that they are interested, for sure:

Federal officials have become increasingly worried that the more than 15 million Americans who received the Johnson & Johnson vaccine face too much risk of severe Covid-19. The Food and Drug Administration on Friday scheduled a meeting on Oct. 15 of its expert advisory committee to discuss whether to grant emergency use authorization of a booster shot of Johnson & Johnson’s vaccine. …

The fact that the advisory committee meeting on Johnson & Johnson was scheduled even before the company filed an application to the Food and Drug Administration reflects a particular sense of urgency in the Biden administration to provide more protection to recipients of that vaccine.

The difference in the FDA’s attitude seems to be on the fact that J&J still has lower efficacy against hospitalization after one shot — 71%, compared to Pfizer’s 88% and Moderna’s 93% after two shots. That CDC-published study was based on real-world data, not test tubes, and did not include anyone with boosters. With the mRNA vaccines, the FDA might be looking at the 93% effectiveness against hospitalization and questioning how much better it will be after a booster, and whether those shots are better off going to unvaccinated people instead. If the gain from an mRNA booster is just a couple of percentage points, it’s probably better to distribute those shots to unvaccinated people, who will gain sixty points or so of potential protection instead.

With J&J, however, the calculus is different. First, the gain is significant — leaping from 71% to 94%. Second, the population of J&J recipients is much smaller (just over 15 million) and not growing much, thanks to the FDA/CDC bumbling that all but erased consumer confidence in the J&J vaccine. It won’t take too many resources to provide them with boosters, and it likely won’t take too many doses away from the unvaccinated, who are migrating mostly to the mRNA vaccines anyway.

Therefore, the FDA may want to plug the gap by making official what seems clearly apparent from the science — the J&J/Janssen vaccine is essentially a two-dose regimen. Waiting six months between doses seems to be the most effective strategy, which makes the timing propitious. Expect the FDA to figure that much out, but perhaps the better question is why it requires an FDA approval at all. The vaccine is already operating under an EUA, and the data makes clear the benefits. Let consumers choose whether to get boosters, perhaps with an FDA recommendation. As a J&J recipient myself, I’m certainly capable of doing the homework and making that decision for myself.

In the meantime, here’s an NBC report on the J&J submission that barely mentions it, but instead mainly features Anthony Fauci … and the news that cases are dropping dramatically at the moment. Fauci’s skeptical about it being an end to the pandemic, natch, but so am I. This is a seasonal-cycle vaccine, and it spikes whenever people have to spend more time indoors whether for excessive heat or cold. Cases are dropping in the South, but the Northeast and upper Midwest had better brace for impact.