Editor's Note: (Megan L. Ranney MD MPH, professor of emergency medicine, director of the Brown-Lifespan Center for Digital Health, and associate dean of the School of Public Health, Brown University. Twitter @meganranney. The views expressed in this commentary are her own. Read more opinion articles on CNN.)
(CNN) For the past few months, as the world has been debating boosters, breakthrough infections, and real-world efficacy, there has been one common refrain in questions I'm being asked on Twitter and in person:
"What about those of us who got J&J?"
Put yourself back in the mindset of February 2021. We were desperately short on vaccines, and I and other medical and public health officials were encouraging folks to "get the first vaccine you're offered." At this moment in time, J&J felt like a game-changer.
It could dramatically increase capacity and reduce supply chain challenges. Its reported efficacy was slightly less than that of Moderna's or Pfizer's mRNA vaccines, but was still strong; clinical trials showed it to be 66% effective at preventing moderate to severe illness, 85% effective against severe disease and 100% effective at preventing death.
As a "one and done" shot, it would also help the needle-phobic, the mRNA hesitant, or just people who would never come back for a second visit to get protected.
But then the bottom dropped out. For a combination of reasons, J&J came to be thought of by some as the third-tier vaccine.
In mid-April, an extremely rare but severe blood clotting syndrome was identified as a possible side effect. And just weeks prior, millions of doses of J&J had to be thrown out due to a manufacturing mix-up.
Some vaccination sites across the country even started phasing it out. The number of new people getting vaccinated with this vaccine slowed to a trickle.
Many of the approximately 14.8 million Americans who received J&J likely and deservedly felt like the forgotten ones. It became increasingly rare for J&J to be the subject of big news updates, while Pfizer and Moderna were garnering attention for the possibility of booster shots.
My own guidance to friends and neighbors evolved to that of New York Times writers David Leonhardt and Ian Prasad Philbrick: proceed at your own risk. J&J recipients started to feel like instead of getting the top shelf choice, they had received the dregs.
Then, finally, this week, we got some good news about J&J. Coming off a disappointing summer surge of Delta, it was just what we needed.
On September 16, a preprint study reported the J&J vaccine maintained its effectiveness against both symptomatic disease and hospitalization between March and the end of July -- despite the rise of the Delta variant.
This finding suggests that J&J is strongly effective against this novel variant. In other words, J&J's vaccine has staying power.
In a moment of tremendous uncertainty, this analysis allows J&J recipients to sleep easier, despite having received only a single shot.
Then, on September 21, a press release from Johnson and Johnson shared more promising data, suggesting with a J&J booster shot, protection against all forms of Covid-19 is, simply, excellent. After an eight-week booster, vaccine efficacy against severe or critical Covid-19 was almost 100% (albeit with a huge amount of estimation: the confidence interval ranged from 33% to 100%), and protection against moderate-to-severe Covid-19 disease was 94% in the US (the confidence interval in this case was 58%-100%). In a pandemic for which nothing has been certain, 100% sounds pretty good.
A six-month booster showed preliminary signs of being even better based on antibody measurements, although actual clinical outcomes have not been reported. Safety metrics, for both the eight-week and six-month boosters, are reportedly excellent.
This press release gives hope for the future for our 14.8 million J&J recipients: If the J&J second dose is granted emergency use authorization by the US Food and Drug Administration, they will not, after all, be left behind if and when boosters are rolled out.
I must, of course, give the usual caveats. These data were released in preprints and press releases. They have not been FDA-reviewed. There are lots of questions still to be answered about age, gender, race and ethnicity. And most importantly, I want to see the data on safety. Although there is a small chance of getting a very unusual type of blood clot from the J&J vaccine, there is also a chance of developing a blood clot from being hospitalized with a Covid-19 diagnosis. But we need to see data on what happens after a second shot, too -- the same caution I've given for boosters for Pfizer and Moderna.
Despite these cautions, the takeaways are positive.
For those who have already received J&J, I now feel confident telling you that you're just as protected as I am (having completed my Pfizer vaccine series more than eight months ago). Hang tight for a booster. Feel better about your choice.
Equally importantly, if you aren't yet vaccinated, J&J is clearly a very good choice. In fact, I am now going to suggest this vaccine a little more strongly to my patients in the emergency department who are not yet vaccinated, and who often face barriers to a two-shot initial regimen.
I'm also hopeful this vaccine, which is easier to transport and administer, can help us meet the immense global need for vaccinations -- without making citizens feel like they're receiving a second-class choice.
The big picture? With these stats in hand, J&J no longer looks like it's a bottom-of-the-barrel choice, after all.