When drug regulators meet later this month to decide whether to let Johnson & Johnson roll out the nation’s third COVID-19 vaccine, the pharmaceutical giant will almost certainly tout an increasingly important selling point: its one-shot vaccine has the highest proven efficacy against a worrisome virus variant that emerged in South Africa and has reached the United States.
That’s the view of several vaccine experts interviewed after the government of South Africa this week abandoned plans to use a rival vaccine developed by AstraZeneca and the University of Oxford. A small clinical trial in that country indicated that vaccine provided “minimal protection” against mild or moderate cases caused by the more contagious and resistant variant.
Despite receiving 1 million doses of the AstraZeneca vaccine on Feb. 1, the South African government shelved its planned rollout and will instead give up to 500,000 front-line health care workers the Johnson & Johnson vaccine, which has yet to be approved by any country. South Africa is also considering deploying vaccines from Pfizer-BioNTech and Moderna, even though they haven’t been tested against the variant in a clinical trial.
An advisory panel to the World Health Organization has expressed confidence in AstraZeneca’s vaccine, a linchpin in the agency’s efforts to vaccinate developing countries, despite the concerns about the South African strain.
Dr. Nelson Michael, director of the Center for Infectious Diseases Research at Walter Reed Army Institute of Research, said he “would be stunned” if the events in South Africa do not come up when an influential advisory committee to the Food and Drug Administration holds a Feb. 26 public hearing on Johnson & Johnson’s request for emergency use.
Given that the South African variant has been detected in at least 32 countries, including at least six cases in three US states, Michael said, it’s “a logical assumption” that the Vaccines and Related Biological Products Advisory Committee will scrutinize how well Johnson & Johnson’s vaccine performed against the variant, known as B.1.351. “That’s going to be something that the VRBPAC will look at favorably,” he added.
Johnson & Johnson reported on Jan. 29 that the vaccine it developed with Beth Israel Deaconess Medical Center in Boston was 66 percent effective at preventing moderate and severe COVID-19 cases globally in a study of 43,783 volunteers. The rate of effectiveness rose to 72 percent in the United States but declined to 57 percent in South Africa, where nearly all the cases were caused by the variant.
Those numbers fell short of the stellar performances of the two-shot vaccines from Pfizer-BioNTech and Cambridge-based Moderna, which had been administered to more than 32.8 million people in the United States as of Tuesday. Those vaccines prevented about 95 percent of coronavirus cases in large trials. But the shots were administered before resistant variants emerged in South Africa and elsewhere, and federal health officials and vaccine experts say the percentages would likely be lower now.
The more important barometer now, experts say, is how the Johnson & Johnson vaccine fares at preventing serious cases, and the data are encouraging. Regardless of where it was tested worldwide, a single shot was 85 percent effective at preventing severe illness and 100 percent effective at preventing COVID-related hospitalization and death four weeks after an injection.
Michael, who has worked on vaccines for diseases such as HIV, Zika, and Ebola, said the overarching goal of inoculation is protection against life-threatening illness.
“We’re not in the business of trying to prevent colds,” he said. “We’re trying to prevent severe disease, hospitalization, and death.”
The halt of the AstraZeneca vaccine rollout was a devastating blow to South Africa. The nation has by far the most COVID-19 cases on the African continent, with nearly 1.5 million confirmed cases, including nearly 47,000 deaths, according to the Johns Hopkins University Coronavirus Resource Center.
The AstraZeneca trial, which included 2,000 participants, found virtually no difference in the numbers of people in the vaccine and placebo groups who were infected with B.1.351, indicating that the vaccine offered little protection against the variant. No one knows yet how well the vaccine would do against a severe form of the disease. The volunteers were young and healthy ― the median age was 31 ― so they were unlikely to become seriously ill. The findings have yet to be published in a peer-reviewed scientific journal.
South African scientists said Sunday that they held out hope the vaccine still might ward off more severe cases, based on the immune responses detected in blood samples from people who were inoculated. But further studies would need to confirm that.
Dr. Larry Corey, a virologist at the Fred Hutchinson Cancer Research Center in Seattle and a leader of the national COVID-19 Prevention Network, which is helping to oversee vaccine trials, said the 57 percent efficacy of Johnson & Johnson’s vaccine in South Africa bodes well for FDA authorization, which already seemed likely.
“I would presume that’s going to be a factor,” he said. “We know that these variants are coming.”
Another experimental vaccine, made by the Maryland biotech Novavax, was also tested in South Africa against the variant, and it performed better than AstraZeneca’s, although not as well as Johnson & Johnson’s; Novavax’s two-shot vaccine was 49 percent effective. The firm has begun a “rolling” submission to get its vaccine authorized by drug regulators around the world, including the FDA.
Dr. Anthony Fauci, the nation’s top infectious disease expert, said during the summer that a COVID-19 vaccine would have to be at least 50 percent effective for the government to authorize it for emergency use. By comparison, the seasonal flu shot is typically 40 to 60 percent effective, according to the Centers for Disease Control and Prevention.
Executives at Pfizer-BioNTech and Moderna have expressed confidence that their vaccines, which were cleared for emergency use in December, should protect people from the South African variant. They have based that on the results of test tube studies showing that blood samples from vaccine recipients had enough antibodies to neutralize the variant.
Moderna acknowledged on Jan. 25 that the South African variant did cause a six-fold decrease in disease-fighting antibodies generated by its vaccine. But the company said the level was likely still sufficient to provide immunity. Fauci agreed, saying the Pfizer-BioNTech and Moderna vaccines should have “enough cushion” in antibodies to work against the variant.
Nonetheless, Moderna said that it will test a reworked version of the vaccine as a booster shot on laboratory animals and then people to see if it’s more effective against the South African variant. The firm also plans to test whether a third shot of the already authorized vaccine increases protection.
Dr. Dan Barouch, who runs the Center for Virology and Vaccine Research at Beth Israel and helped design the Johnson & Johnson vaccine, said no other drugmaker has proof that its vaccine protects most people against the South African variant.
“Clinical efficacy trumps laboratory measures because we don’t yet know exactly which laboratory measures are necessary for protection,” said Barouch, whose hospital licensed vaccine technology to Johnson & Johnson.
He said a viral variant that first emerged in the United Kingdom and is spreading quickly in the US worries him far less than the South African variant.
“The world has woken up,” he said. “The South African variant is really the one threatening pandemic control in the world.”
The federal government has a deal with Janssen Pharmaceuticals, a Johnson & Johnson subsidiary, worth about $1 billion for 100 million vaccine doses that Janssen has promised to deliver by the end of June. Because the vaccine can be administered in one shot, that would mean full coverage for 100 million people. The agreement gives the government the option to order an additional 200 million doses.
In addition to the advantage of requiring one shot instead of two, the Johnson & Johnson vaccine is stable at normal refrigerated temperatures. The Pfizer and Moderna vaccines must be frozen at ultracold temperatures until being thawed before vaccination.
Jonathan Saltzman can be reached at email@example.com.