Single-shot Johnson & Johnson vaccine prevents illness but shows the threat of variants

A single-shot coronavirus vaccine produced by pharmaceutical giant Johnson & Johnson was robustly effective at preventing illness, hospitalizations and deaths in a massive global trial, findings released Friday show. But its protection against sickness was stronger in the United States and weaker in South Africa, where a worrisome coronavirus variant dominates — a complicated result that reflects the evolution of the pandemic.

The results, reported in a news release, put a third vaccine on the horizon in the United States — one with logistical advantages that could simplify distribution and expand access to shots domestically and worldwide. A third vaccine could accelerate the increasingly urgent race to broaden immunity as variants that challenge the current generation of vaccines spread across the world.

The vaccine trial was primarily designed to measure how well the vaccine prevented illness. It was 66 percent effective overall at preventing moderate and severe disease four weeks after the shot, a result that covers a wide range of variation depending on geography: it was 72 percent effective at protecting against moderate to severe illness in the United States, but it was 66 percent effective in Latin America and 57 percent effective in South Africa, where concerning variants have taken root.

Company executives emphasized that the vaccine was 85 percent effective at preventing severe illness and that there were no cases of covid-related hospitalization and death — the outcomes that most people would like to avoid — in people who received the vaccine. Five covid-related deaths were reported in the trial, all among groups that received the placebo, not the vaccine.

Johnson & Johnson is expected to apply for emergency use authorization from the Food and Drug Administration late next week. If the review follows the path of two earlier vaccine candidates, the shot could be authorized and available to the public by March.

But production setbacks mean federal officials are initially expecting only a trickle of doses if the FDA quickly authorizes the product for emergency use. That would amount to doses in the single-digit millions at first, not ramping up to 20 million or 30 million until the spring, according to two federal officials who spoke on the condition of anonymity because of the matter’s sensitivity. Company executives declined to provide additional information on the quantity of doses likely to be available month by month, but said they would deliver 100 million doses in the first half of the year.

The FDA said a vaccine must be at least 50 percent effective to be authorized, a bar the Johnson & Johnson shot appears to have cleared, although the data will undergo careful and more detailed review by career FDA scientists and an outside panel of experts. Safety data also will be carefully reviewed, although the company said the shot had tolerable side effects, including fever and no serious safety concerns. There were no cases of anaphylaxis, an extreme allergic reaction.

If the Johnson & Johnson shot is authorized, it would diversify the supply beyond two companies, something that many experts have hoped for in case of manufacturing delays or production lines going down because of contamination or other unexpected events. Temte recalled a shortage of the Hib vaccine given to children starting in late 2007 when problems with one manufacturer took production offline for more than a year, leaving the United States reliant on a single company for its supply.

Johnson & Johnson will make its vaccine in the Netherlands and through partnerships with firms such as Emergent BioSolutions, a contract development and manufacturing company headquartered in Gaithersburg, Md.

The new vaccine uses a different technology from the two vaccines authorized in the United States, broadening the suite of tools to block the virus. The Johnson & Johnson vaccine employs a harmless cold virus to deliver a gene that carries the blueprint for the spiky protein found on the surface of the coronavirus. The virus infects cells, which then follow the genetic instructions to construct a replica of the coronavirus spike.