The Johnson & Johnson vaccine against COVID-19 might have fallen out of favor in the US, but it has proven effective here and especially overseas. The New York Times reported late yesterday that a study of real-world performance in South Africa shows their vaccine works effectively against all variants against serious symptomatic cases and death. Its impact is long-lasting enough that J&J recipients may not need a booster shot at all:

A single dose of the Covid-19 vaccine made by Johnson & Johnson is highly effective in preventing severe illness and death from the Delta and Beta variants of the coronavirus, data from a clinical trial in South Africa suggest.

The study is the first real-world test of the vaccine’s efficacy against Delta, a highly contagious variant of the virus surging across the United States and much of the world. South Africa’s Ministry of Health reported these preliminary results at a news conference on Friday. The data have not yet been peer-reviewed or published in a scientific journal.

In the trial, called Sisonke, the researchers evaluated one dose of the Johnson & Johnson vaccine in nearly 500,000 health care workers, who are at high risk of Covid-19. The vaccine has an efficacy of up to 95 percent against death from the Delta variant, and up to 71 percent against hospitalization, the researchers reported. (The vaccine did slightly worse against the Beta variant, which is thought to be more adept at sidestepping the immune response than Delta.)

That’s not quite the same level of effectiveness as the Pfizer and Moderna two-shot vaccines appear to provide, but this is one of the first studies to explicitly include a Delta-dominated field. Moderna and Pfizer have both suggested that they may need a third shot to deal with the variants, but this study suggests a single J&J (also known as Janssen) shot is sufficient — even to deal with the breakthrough cases:

The results suggest that people who have received one dose of the Johnson & Johnson vaccine don’t need a booster shot, Dr. Bekker said.

When so-called breakthrough infections did occur in vaccinated volunteers, they produced mild symptoms in 96 percent of the cases and resulted in severe disease or death in less than 0.05 percent, the study found. The trial ran from February to May of this year.

Delta hit South Africa well before it became dominant in the US. We haven’t done many studies here on the J&J vaccine because of its unfortunately limited use in the US. One widely-reported study from last month wasn’t using real-world data to determine efficacy, but only lab work despite the still-significant numbers of recipients in the US (myself among them). J&J’s own study, a longitudinal study of recipients, was much more optimistic. This new study of real-world performance in “one of the most challenging epidemiological settings,” as an outside expert noted, corroborates the latter study and again calls into question why anyone would do lab studies on vaccines rather than study the outcomes from millions or tens of millions of recipients.

That’s good news for the smaller number of J&J recipients in the US, and a bit of a black eye to the bureaucrats that derailed it too precipitately over initial reports of blood clotting. The study in South Africa only found two such cases in their sample of 500,000 recipients, a lower rate than the condition appears normally in people. Both cases had a full recovery. Imagine if we hadn’t undermined public confidence in the J&J vaccine with the panicked recall this spring. We could have perhaps fully inoculated tens of millions more Americans by now and curtailed the transmission potential of Delta, thanks to its one-and-done architecture.

The news isn’t quite so good for another long-awaited vaccine from Operation Warp Speed. Novavax disclosed that the FDA has stalled its production of its highly anticipated vaccine candidate, one which has demonstrated 90% effectives against COVID-19 and 100% effectiveness against death, over quality control concerns:

Novavax, the Maryland firm that won a $1.75 billion federal contract to develop and produce a coronavirus vaccine, said on Thursday that the federal government would not fund further production of its vaccine until the company resolves concerns of federal regulators about its work.

The disclosure came in a quarterly filing with the Securities and Exchange Commission. The Trump administration agreed to buy 110 million doses of vaccine from Novavax as part of its crash vaccine development program.

Although the company reported in June that its vaccine had an efficacy of 90 percent against symptomatic Covid-19 cases, and 100 percent against severe disease, Novavax has struggled for months to mass manufacture its product. Its vaccine has not been authorized for distribution in the United States, and federal officials said it is unclear when or if it will be.

Four people familiar with Novavax’s operation said the company had been unable so far to demonstrate that its production process met Food and Drug Administration standards.

The FDA continues to fund the clinical trials of the Novavax vaccine, so they should get a more complete picture of its impact. Without full production taking place in parallel, however, even an approval would still leave the company months away from any robust deliveries. That would leave it more as a candidate for export, but probably too far off to have much impact on the US.