By Madeline Keleher
Mar 13, 2021
The media has conveyed the sentiment of “meh” for the newly approved Johnson & Johnson coronavirus vaccine, with some articles even calling it disappointing. Detroit’s mayor went so far as to turn down a shipment of 6,200 doses of the J&J vaccine, saying although it was “very good,” his constituents deserved “the best”—that is, the Moderna and Pfizer vaccines. So, is it worth getting the J&J vaccine? Let’s look at the data.
The Moderna and Pfizer vaccines are mRNA instructions that enter your muscle cells and direct the assembly of the coronavirus spike protein, which your body then quickly makes antibodies to destroy. The J&J vaccine consists of DNA instructions for the spike protein, which enter your muscle cells and are transcribed to mRNA, which then builds the spike protein for your antibodies to annihilate. Because the J&J instructions are made of DNA—a much more stable molecule than mRNA—the vaccine is easier to ship, easier to store, and lasts much longer in the fridge than the Moderna and Pfizer vaccines. Thus, it will vastly improve vaccine distribution to underserved and rural areas lacking ultra-cold storage, although some people question the ethics of targeting a “less effective” vaccine to impovershed areas.
It is crucial to understand this issue of efficacy. The J&J vaccine’s efficacy at preventing Covid-19 is 66%, whereas Moderna’s is 94% and Pfizer’s is 95%. 66 is less than 95, so J&J’s is a less effective vaccine, right? Well, no, actually. I know it sounds like I’m saying 1+1=3, but bear with me a minute.
Moderna and Pfizer conducted their clinical trials last summer and fall, when new coronavirus cases in the United States were hovering around 50,000 per day. J&J, however, conducted their trial during the fall and winter, with cases soaring well over 100,000 per day (and over 200,000 per day in December and January). And while all of Moderna’s volunteers were in the United States, as well as 77% of Pfizer’s, only 47% of J&J’s volunteers were in the US. The rest were in South Africa (13%), Brazil (17%), and other Latin American countries (23%). This is important because the coronavirus is mutating, and some of the new variants have altered the shape of their spike proteins in such a way that they can elude our antibodies. In the J&J trial, most of the South African cases (94%) were caused by the exceedingly contagious B.1.351 variant and most of the Brazilian cases (69%) were caused by the P.2 variant, whose spike protein carries the E484K mutation that enhances it ability to escape antibodies. The J&J vaccine did perform better (72% efficacy) in the US than countries where the new variants were more rampant.
95% efficacy refers only to the ~2 month follow-up in the trial period; 8 people, or 0.04% of the Pfizer vaccine group, got Covid-19 during the trial, while 162 people (0.88%) from the placebo group did. To get efficacy, you calculate the difference between the placebo and vaccine groups (0.88% - 0.04% = 0.84%) and divide that difference by the infection rate in the placebo group: 0.84/0.88 = 95% efficacy. It doesn't mean that 95% of vaccinated people won't get Covid-19 this year; risk compounds with time. Note that only 0.88% of people receiving a placebo contracted Covid-19 during the short duration of the trial, whereas more than 20% of Americans have had Covid-19 in the last year. The Pfizer trial was thorough and successful, but captured only a brief snapshot of time--and times have changed. Many of the participants weren't even exposed to the coronavirus during the trial, let alone to variants. We don't know if the ratio of cases between the vaccine and placebo groups would hold over more than 2 months, then, now, or in the future. It's wrong to compare the participants of the mRNA trials with the participants of the J&J trial, who were exposed to the coronavirus (in its now many variant forms) at much higher rates.
So, the participants in the J&J trial were not only more likely to get exposed to the coronavirus than the Moderna and Pfizer participants, they were far more likely to be exposed to a more contagious variant. It’s like testing one company’s new raincoat in a drizzle and another company’s raincoat in a hurricane, and saying the latter coat was less effective at preventing wetness. Context matters.
Despite the more grueling conditions faced by the J&J trial, the vaccine was still 100% effective at preventing hospitalizations and deaths from Covid-19. One hundred percent. This vaccine can save your life. It will save countless of lives worldwide.
At the end of the day, we shouldn’t be comparing the J&J vaccine with the Moderna and Pfizer vaccines. We could test all three vaccines concurrently in a study to see if there are true efficacy differences, but no one has done that yet. We don’t know how the Moderna and Pfizer vaccines would fare in today’s conditions, but preliminary data suggests they’d do worse than in the trials last year. In the lab, the P.1 and B.1.351 coronavirus spike proteins showed resistance to antibodies from volunteers fully vaccinated with the Moderna and Pfizer vaccines—and these variants were completely resistant to antibodies from volunteers who had received just one mRNA vaccine dose. Even though 76% of the residents of Manaus, Brazil had already gotten Covid-19 by last October, hospitalizations soared this January when a new variant began re-infecting people. I already know someone in the US who contracted Covid-19 weeks after being fully mRNA vaccinated—fortunately it was a mild case. But this underscores why fully vaccinated people should still wear masks and socially distance in public. The variants are out there and more will arise as long as the pandemic rages around the globe. As the saying goes, no one is safe until everyone is safe.
To recap, the Johnson & Johnson vaccine is a single dose, it can be more easily shipped and stored than the mRNA vaccines, and it offered 100% protection against Covid-19 hospitalizations and deaths in the trial. It was tested in a more diverse cohort of people than the mRNA vaccines, in countries where variants raged—and still no one who received the vaccine died of Covid-19. It has fewer side effects and brings immunity 7-14 days sooner than the mRNA vaccines. When it is finally my turn to be vaccinated, I will take whichever vaccine is offered to me, without hesitation. Whether it’s the Moderna, Pfizer, or J&J vaccine, I will be jubilant.
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