Preliminary results are out for the J&J single-shot vaccine candidate. Efficacy against moderate and severe Covid-19 after 28 days was 72% in the US and 66% overall worldwide, and did not vary by age or race.

Efficacy against severe disease was 85% in adults 18 and older. Overall efficacy in Central / South America was 66% and in South Africa, 57%. A total of 468 cases of moderate or severe Covid-19 resulted in the study of 43,783 participants. In the vaccine arm of the trial, no one was hospitalized or died from the disease.

Here are J&J’s press release and a summary by Stat News.

In terms of safety, the company said that 9% of volunteers reported fever and 0.2% high fever (104°F or above). The majority of the latter group were in the placebo arm of the trial. There were no incidences of anaphylaxis.

The company is also running a Phase III trial using two shots of the same vaccine candidate. That protocol calls for 8 weeks between the doses, so this study won’t read out until late summer or fall. The company ex­pects to see higher efficacy numbers in the two-dose regimen.

J&J’s candidate, like the Oxford / AstraZeneca vaccine, delivers spike protein via a replicating Ad26 adeno­virus. It is stable for 3 months at refrigerator temperature and for 2 years at ordinary freezer temper­ature.

The company says it will submit results to a scientific journal for publication within a few weeks and will file for FDA emergency use auth­or­i­za­tion in early February. J&J will have doses ready to ship upon auth­or­i­za­tion. While the efficacy of this vaccine candidate does not reach the high bar set by Pfizer / BioNTech and Moderna, it is above the level the FDA said it will consider to grant an EUA.

Efficacy against variants: The lower efficacy in the South African region (57%) was probably due to the pre­val­ence of the new, more contagious B.1.351 lineage, which laboratory studies indicate is more resistant to the neutralizing antibodies produced by vaccination or natural infection. The lower efficacy in South America (66%) may have been skewed by the similar B.1 variant in Brazil, which is spreading fast but is not as dominant there as B.1.351 is in South Africa.

Equity: Once J&J is authorized, I foresee squabbles over which communities are allocated “the good stuff” (i.e. Moderna and Pfizer) and which get the less efficacious, but logistically simpler, J&J vaccine. This will play out on local and national levels.

My expectation is that for many months to come, those of us waiting to get vaccinated will have no choice as to which vaccine goes into our arms.