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J&J COVID-19 vaccine advisory committee meeting to focus on serious disease, variants

Feb 25, 2021 | 2:26 AM GMT

The Feb. 26 FDA advisory committee meeting about Johnson & Johnson’s COVID-19 vaccine candidate is likely to focus on the vaccine’s strong efficacy in preventing serious disease and hospitalization and its efficacy against SARS-CoV-2 variants.

The committee will also hear presentations from CDC about the epidemiology of SARS-CoV-2 variants and postmarketing surveillance of the two authorized COVID-19 vaccines.

Data released ahead of the Vaccines and Related Biologic Products Advisory Committee (VRBPAC) meeting indicate that the vaccine developed by the Janssen unit of Johnson & Johnson (NYSE:JNJ) “is highly effective in the prevention of severe/critical COVID-19, particularly in prevention of hospitalization and death, across all countries and all ages,” J&J stated in its review.

Efficacy of COVID-19 Vaccine Janssen (Ad26.COV2.S, JNJ-78436735) against severe/critical COVID-19 diagnosed at least 14 days after vaccination with the vaccine was 76.7%, with a lower bound of the 95% confidence interval of 54.6% and an upper bound of 89.1%. The point estimate for efficacy increased to 85.4% 28 days after vaccination.

FDA’s review said a post-hoc analysis revealed there were two cases of COVID-19-related hospitalizations starting 14 days after vaccination and none after day 28 in the vaccine group, compared with 29 cases after day 14 and 16 cases after day 28 in the placebo group. As of Feb. 5, seven COVID-19-related deaths were reported in the placebo group versus none in the vaccine group.

Though the J&J vaccine demonstrated substantially lower efficacy – 66.5% – against all symptomatic disease than vaccines from Moderna Inc. (NASDAQ:MRNA) and partners Pfizer Inc. (NYSE:PFE) and BioNTech SE (NASDAQ:BNTX), which both read out at about 95%, the difference is not likely to prevent the committee from recommending emergency use authorization. 

One reason is that keeping people out of the hospital and preventing deaths are critical public health objectives and keys to restarting society. Another consideration is that J&J tested its vaccine later in the pandemic, after the rise of variants, which could make direct comparison to previous trials difficult. 

The efficacy of COVID-19 Vaccine Janssen was maintained through the four-month study period, alleviating concerns about the duration of protection provided by a single-dose vaccine. AstraZeneca plc (LSE:AZN; NASDAQ:AZN) has reported that the efficacy of one dose of its adenoviral vector vaccine is maintained for 90 days then falls to less than half.

It’s not clear why J&J’s vaccine has more durable efficacy than AZ’s, in part because antibody and T cell data from early stage trials aren’t directly comparable due to differences in how the companies measured and reported them. Lack of harmonized antibody assays has been a problem for cross-trial comparisons across all COVID-19 vaccines.

The difference in durability could come down to the two adenovirus vectors used in the vaccines. J&J’s vector might last for longer in cells, or because it is a human vector and AZ’s is from chimpanzee, it could replicate better in people.

J&J is conducting trials of a two-dose regimen of its vaccine, as well as trials of different doses.

FDA downplayed regional differences in efficacy, stating in its review that while there was country-to-country variation in vaccine efficacy, the confidence intervals around estimates for the prevention of moderate to severe/critical COVID-19 and severe/critical COVID-19 overlapped.

In an addendum to its VRBPAC briefing memo, J&J reported that “robust” vaccine efficacy was observed for moderate-to-severe/critical COVID-19 in studies conducted in South Africa. It added that the observation “is especially important since preliminary sequence data confirm that approximately 94.5% (86/91 sequenced samples) of the COVID-19 cases that occurred in the study in South Africa were due” to the B.1.351 variant first identified in the country.

In South Africa, vaccine efficacy against moderate-to-severe/critical COVID-19 was 52% at least 14 days and 64% at least 28 days after vaccination.

J&J reported that efficacy numbers in Brazil “were higher than those in South Africa and similar to those in the U.S.”

If the vaccine receives emergency use authorization, J&J plans to offer all placebo patients the opportunity to receive the vaccine, and to extend this offer to placebo recipients in ongoing Phase I and II studies.

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