Will the Johnson & Johnson vaccine be as effective as Pfizer and Moderna? (Updated)

johnson & johnson vaccine efficacy
Photo via Chairman of the Joint Chiefs of Staff/Flickr (CC BY 2.0)

This story is regularly updated for relevance. Last updated: May 24, 2021

With Johnson & Johnson getting emergency approval by the FDA, preliminary signs showed its efficacy might not be as great as the previously-approved Pfizer and Moderna vaccines. Yet, it’s still efficient enough to be useful in the fight against the COVID-19 pandemic. 

Until, that is, the U.S. stopped giving the vaccine on April 13 after six people (out of the nearly 7 million who had previously gotten it) developed a potentially deadly blood-clotting disorder.

On April 23, the U.S. lifted the temporary ban for its citizens, even though people, on rare occurrences, were still developing blood clots (and, according to CNN data, a person is 40 times more likely to die from COVID than they would be to die from blood clots caused by the vaccine).

In mid-May, the Biden administration stopped shipping the vaccine because of domestic production issues, though that could only be a temporary decision. Soon after, it was reported that more than 100 million doses had been held up so inspectors could make sure they weren’t contaminated.

Operation Warp Speed chief adviser Moncef Slaoui expects “high efficacy” for the Johnson & Johnson vaccine, he said via Reuters, with an optimistic projection of 80-85% effectiveness. The single-dose vaccine doesn’t require the ultra-cold storage of the two vaccines currently in circulation in the U.S., giving it clear distribution advantages over the two-dose Pfizer and Moderna versions.

On Jan. 29, Johnson and Johnson said, via the Associated Press, that the vaccine was 66% effective against COVID-19 and 85% effective against the disease’s most serious symptoms.

“Gambling on one dose was certainly worthwhile,” Dr. Mathai Mammen, global research chief for J&J’s Janssen Pharmaceutical unit, told the AP.

A Jan. 13 Fortune article pointed out that the Johnson & Johnson vaccine “generated a long-lasting immune response in an early safety study, providing a glimpse at how it will perform in the real world as the company inches closer to approaching U.S. regulators for clearance.” 

“More than 90% of participants made immune proteins, called neutralizing antibodies, within 29 days after receiving the shot,” the story noted, “and all participants formed the antibodies within 57 days. The immune response lasted for the full 71 days of the trial.” 

That gave the company’s chief scientific officer, Paul Stoffels, optimism for the results of the latest phase of the clinical trials. “Looking at the antibodies, there should be good hope and good reason that the vaccine will work,” he said in an interview Jan. 12. 

Should the timetable for those go as expected, the Johnson & Johnson vaccine, with its optimistic efficacy, should be approved for use as early as February, though the Fortune article foresaw a March approval. 

CNN noted that results of Phase 1/2 trials, published Jan. 13 in the New England Journal of Medicine, “found either one or two doses of the vaccine generated both antibody and T-cell responses against the coronavirus.” The report also noted that the Ad26.COV2.S vaccine, which uses a weakened form of a common cold virus, is ruled safe for use, with side effects including headaches, body aches, and, in rare cases among the approximately 800 participants, fever. 

For context, the Moderna and Pfizer vaccines are about 95% effective, while the Sputnik vaccine from Russia is 91.6% effective.

As CNBC noted, the U.S. Department of Health and Human Services announced this past August that it paid approximately $1 billion for 100 million doses of the vaccine August to Janssen—Johnson & Johnson’s pharmaceutical subsidiary—with an option to order an additional 200 million doses.

According to the AP, Johnson & Johnson “said its vaccine works consistently in a broad range of people: A third of participants were over age 60, and more than 40% had other illnesses putting them at risk of severe COVID-19, including obesity, diabetes, and HIV.”

In late February, the FDA approved the Johnson & Johnson vaccine for emergency use, giving the U.S. a third vaccine. On March 10, Biden said the U.S. had “secured” another 100 million doses of the Johnson & Johnson version (it’ll deliver 20 million doses to the government by April 1). If there are surpluses of the vaccine once every American who wants one can get one, the administration said it would send doses to other countries in need.

On April 1, there was bad news when the New York Times reported that 15 million Johnson & Johnson doses had been compromised in a Baltimore plant after workers mixed up the ingredients of the vaccine, delaying huge shipments that were supposed to be sent around the country.

In South Africa, which recently paused its use of AstraZeneca because early trials showed it wasn’t effective against the variant that originated in that country, it began using the Johnson & Johnson vaccine on its citizens. In late February, it was reported that the vaccine performed even better in South Africa than the original data showed.

Janssen, which produces the Johnson & Johnson vaccine, is hoping in the summer of 2021 to begin phase 1 trials of a version of that vaccine that would focus on the COVID variants.

Read more on the coronavirus vaccine:

Sources: Reuters, Fortune, CNN, CNBC

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