UT Southwestern Vaccine Science Review Committee Scientific Review of Janssen Biotech Inc. COVID-19 Vaccine (Ad26.COV2.S) March 1, 2021

Introduction

On Feb. 27, 2021, the Food and Drug Administration (FDA) granted an emergency use authorization (EUA) for the Janssen vaccine, Ad26.COV2.S, for use in persons 18 years of age or older for the prevention of coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This followed a unanimous approval vote by the Vaccines and Related Biological Products Advisory Committee (VRBAC) cast on the previous day. Then, on Feb. 28, 2021, the Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices (CDC ACIP) recommended the use of this vaccine through the EUA for persons 18 years of age or older in the U.S. for the prevention of COVID-19.

The UT Southwestern Vaccine Science Review Committee for COVID-19 is a multidisciplinary group of immunologists, infectious diseases experts, epidemiologists and other key stakeholders tasked with independently reviewing the available evidence in support of COVID-19 vaccine candidates on behalf of our campus community. Below, we summarize our current assessment of the available evidence for the Janssen Ad26.COV2.S vaccine based on the FDA emergency use authorization and ACIP recommendations, supporting documentation reviewed by the FDA, and the published medical literature.

Janssen Ad26.COV2.S Vaccine

A. Vaccine Product Information The Janssen COVID-19 vaccine, Ad26.COV2.S, is a recombinant, replication-incompetent adenovirus type 26 (Ad26) vectored vaccine encoding a stabilized variant of the SARS-CoV-2 Spike (S) protein. The Ad26 vector is grown in PER.C6 TetR cells, in media that contains amino acids but no animal-derived proteins. After propagation, the vaccine undergoes several purification steps, is formulated with inactive ingredients and filled into vials. The vaccine is administered as a single IM injection that is 0.5 mL, and contains 5x1010 viral particles. After intramuscular administration, the vector vaccine enters human cells, and the expression of the SARS-CoV-2 S protein occurs in the absence of viral replication. The vaccine itself contains the following inactive ingredients: citric acid monohydrate, trisodium citrate dihydrate, ethanol, 2- hydroxypropyl--cyclodextrin, polysorbate-80, and sodium chloride. Additional product information can be found in the FDA’s emergency use authorization information: https://www.fda.gov/media/146304/download

B. Safety Experience of Ad26-Based Vaccines The Ad26 vector platform has been used in the past, and there is clinical experience utilizing it in the Ebola vaccine regimen (approved by the European Medicines Agency on July 1, 2020) and investigational vaccines against Zika, filovirus, HIV, HPV, malaria and respiratory syncytial virus. As of December 2020, Ad26-based vaccines have been used to vaccinate 193,831 participants in clinical studies and vaccination programs, and have exhibited acceptable clinical safety.

C. Phase 1/2/3 Human Clinical Trials Data The sponsor is conducting a series of randomized, double-blind placebo-controlled human clinical trials in collaboration with the National Institutes of Health (NIH), Biomedical Advanced Research and Development (BARDA), and Operation Warp Speed (OWS). The first two (Studies 1001 and 1002) were dose-ranging phase 1 and 1/2a studies enrolling 250 and 1,045 adults, respectively, with an endpoint of safety and immunogenicity. Combined, these studies confirmed that a single dose of the Ad26.COV2.S COVID–19 vaccine at the 5x1010 viral particle (vp) dose level elicited a Spike protein antibody response by Day 29 that was capable of neutralizing the SARS CoV-2 virus. A T-helper cell type 1 (Th-1) cellular immune response against peptides from the Spike protein was also demonstrated. Study 2001 is a dose-ranging phase 2a study that is currently enrolling adults and adolescents (none of the latter yet enrolled) in one- and two-dose regimens. The study will evaluate the safety and reactogenicity of the vaccine. The humoral (antibody) immune response will be monitored four or six months post- vaccination. Interim results show consistent neutralizing antibody responses with Study 1001 and no significant safety concerns. An additional forthcoming study (Study 3009) is a phase 3 efficacy and safety study utilizing a two-dose regimen that is currently enrolling a planned 30,000 participants; while efficacy data are still pending, no safety concerns have been identified.

Study 3001 has completed enrollment of 43,783 adults and was the basis of the EUA application. This phase 3 trial is a pivotal, multicenter, randomized, double-blind, placebo-controlled efficacy and safety study conducted in eight countries, with the United States enrolling the highest number of subjects (19,302). The subjects were 45 percent female and 55 percent male, with 58.7 percent identifying as White, 19.4 percent Black or African American, 45.3 percent Latinx, 3.3 percent Asian, 9.5 percent Native American/Alaskan, and 0.2 percent Native Hawaiian or Pacific Islander. Of note, there were 4,217 (9.6 percent) of subjects who were seropositive at baseline. Demographics were similar between the treatment and placebo groups. The co-primary endpoints evaluated the first occurrence of moderate-severe/critical COVID-19 confirmed by PCR with onset of symptoms at least 14 days and at least 28 days after vaccination. Final determination of severe/critical COVID-19 cases were adjudicated by an independent committee. Median follow-up was eight weeks post-vaccination. As of the primary analysis cut-off date (Jan. 22, 2021), there were no COVID-19-related deaths reported in vaccine recipients, compared with five COVID-19-related deaths in placebo recipients who were SARS-CoV-2 PCR-negative at baseline. There were also no hospitalizations in the vaccine group who were at least 28 days post-vaccination, compared with 29 hospitalizations in the placebo group. Vaccine efficacy for the co-primary endpoints against moderate-severe/critical COVID-19 in patients where were seronegative at baseline was 66.9 percent at least 14 days post-vaccination and 66.1 percent for subjects at least 28 days post-vaccination. There were no differences in efficacy between subjects older than 65 years of age and younger individuals. Local site pain was the most common adverse event occurring in 58.6 percent of the vaccine group and 17.4 percent of the placebo group 18 to 59 years of age, followed by headache (44.4 percent vs. 24.8 percent), fatigue (43.8 percent vs. 22 percent) and myalgias (39.1 percent vs. 12.1 percent). Adverse events were less common in older individuals. D. Regulatory Guidance from the FDA and CDC ACIP Committees Janssen’s EUA application was reviewed by the external Vaccines and Related Biological Products Advisory Committee (VRBPAC) of the FDA on Feb. 26, 2021. The FDA’s pre- specified criteria for COVID-19 vaccine EUA was at least 50 percent efficacy for the primary outcome (with a lower confidence bound greater than 30 percent), as well as a median follow-up of two months following vaccine completion for safety outcomes. The VRBPAC unanimously recommended that the FDA approve this vaccine for persons 18 years of age and older for the prevention of COVID-19 based on the available data. The only listed contraindication is a history of severe allergic reaction (e.g., anaphylaxis) to any of the components of the Janssen COVID-19 vaccine, Ad26.COV2.S. The EUA does indicate that the efficacy and safety of the vaccine in certain special populations, including pregnant and lactating women, is currently unknown. It also states that there is no data on the interchangeability of this vaccine with other COVID-19 vaccines, but the CDC has discussed that the Ad26.COV2.S vaccine may be offered to people who had an allergic reaction to the first dose of either mRNA vaccine.

E. Clinical Considerations when administering the Janssen COVID-19 vaccine In accordance with the ACIP’s guidance, the Vaccine Science Review Committee recommends patients receiving the vaccine be queried for severe allergic reactions to vaccines, vaccine components, or other injectables. The vaccine should also be administered alone with a minimum interval of 14 days before or after administration of any other vaccines. Vaccination should be offered regardless of history of prior SARS-CoV-2 infection, but deferred until after recovery from acute illness. If the patient received a infusion or convalescent plasma for previous SARS CoV-2 infection, vaccination should be deferred until at least 90 days after the infusion to avoid interference of the treatment with the vaccine-induced immune response. Although there is little data on the safety and efficacy of the adenoviral vector COVID-19 vaccine for pregnant or lactating women, based on current knowledge, there is no evidence of a risk to the pregnant person, fetus or breast-fed baby. Pregnant women in all trimesters were included in the large-scale Ebola vaccine trials without evidence of adverse outcomes. We agree with the CDC and American College of Obstetrics and Gynecology recommendations that the vaccine should not be withheld from pregnant/lactating women if they choose to be vaccinated. Additionally, although there is little data on efficacy in immunocompromised individuals, given that this vaccine utilizes a replication-incompetent adenoviral vector, it has an acceptable safety profile for this high-risk population.

F. Comparison between the available SARS-CoV-2 vaccines The Vaccine Science Review Committee acknowledges that the available COVID-19 vaccine clinical trials were done with different clinical trial designs and endpoints, at different geographic regions and time points in the pandemic, and that the latest trial was performed with new circulating viral variants not recognized during the trials for the available mRNA vaccines ( and ). Therefore, these vaccine trials should not be compared head-to-head. However, in a transparent reporting of the available results, the vaccines performed consistently in both the immune response generated and the clinically important outcomes of preventing hospitalization and death due to COVID-19. Additionally, the Janssen vaccine may be preferable to some patients due to its single-dose regimen.

Vaccine Characteristics Pfizer Moderna Janssen

BNT162b2 mRNA-1273 Janssen Ad26.COV2.S mRNA vaccine (SARS-CoV-2 mRNA vaccine (SARS-CoV-2 Spike) Adenovirus + SARS-CoV-2 Spike Spike) Two doses Two doses One dose 10 30 ug/each (0.3 ml) 21 days apart 100 ug/each (0.5 ml) 28 days apart 5 x 10 viral particles (0.5 ml) o o Stored frozen minus-80 C Stored frozen between minus-15-25 C May be stored for two years at o (likely to change) minus-20 C o o Use within two hours at RT Use 30 days at 2-8 C Three months 2-8 C

Vaccine Immunologic Response and Clinical Efficacy Pfizer (two doses) Moderna (two doses) Janssen (one dose)

Neutralizing Spike Antibodies >98% (post-day 7-dose 2) >98% (post day 14-dose 2) >96% (post-day 28)

CD4 Th1 response 9/9 [0.1% of T cells] [0.1% of T cells] >69% [0.1% of T cells]

CD4 Th2 response undetectable undetectable undetectable

CD8 T cell response 10/11 [0.15% of T cells] [0.1% of T cells] >61% [0.1% of T cells]

COVID-19 Positivity 8 vs. 162 (~18,000/group) 5 vs. 90 (~14,000/group) See below (n, vaccine vs. placebo) Moderate/severe COVID-19 Not reported as such Not reported as such 66 vs. 199 (n, vaccine vs. placebo) (~19,000/group)

COVID-19 0 1 0 needing hospitalization, vaccine group (n)*

* After two doses of mRNA vaccines; after 28 days from first dose for J&J (Janssen) vaccine

UTSW Vaccine Science Review Committee Recommendations and Conclusions

Based on our independent review of the available scientific evidence regarding the efficacy and safety of the Janssen COVID-19 vaccine, Ad26.COV2.S, we concur with the FDA and CDC ACIP recommendations endorsing its use in persons 18 years of age and older for the prevention of COVID-19 in accordance with the EUA. We find that the peer-reviewed scientific data available exceeds the prespecified EUA criteria for vaccine authorization in a rigorous phase 3 trial with sufficient power to assess both the efficacy and safety profile of this vaccine. Although the reported efficacy in preventing less severe cases of COVID-19 is lower than that reported in the mRNA vaccine trials, we believe this difference may be explained by differences in trial design, the time points in the pandemic when the respective trials were conducted, and the prevalence of circulating viral variants. Regardless, the Janssen adenoviral-vectored vaccine was 100 percent effective in preventing the most severe clinical outcomes, hospitalization and death from COVID-19. Given that the COVID-19 vaccine is still a scarce resource and that the pandemic continues to claim lives, we agree with the CDC that these vaccines are equivalent in the most important outcomes and recommend that our patients and employees pursue whichever vaccine is first available to them. Consistent with ethical and legal principles, we believe that vaccine allocation to UTSW employees and patients should proceed in accordance with the previously recommended allocation phases, since there is no data to suggest modifications based on vaccine-specific efficacy or safety in particular subpopulations. The Vaccine Science Review Committee will continue to monitor for additional efficacy or safety data for this vaccine, or other candidate COVID-19 vaccines, and will update its recommendations as appropriate based on new findings.

References

Sponsor Briefing Document: COVID-19 Vaccine Ad26.COV2.S VAC31518 (JNJ-78436735). Vaccines and Related Biologic Products Advisory Committee, Meeting 2/26/2021. fda.gov/media/146219/download Accessed 3/1/21.

Sponsor Briefing Document Addendum: COVID-19 Vaccine Ad26.COV2.S VAC31518 (JNJ- 78436735). Vaccines and Related Biologic Products Advisory Committee, Meeting 2/26/2021. fda.gov/media/146218/download Accessed 3/1/21

FDA Briefing Document: Janssen Ad26.COV2.S Vaccine for the Prevention of COVID-19. Vaccines and Related Biologic Products Advisory Committee, Feb. 26, 2021. fdanews.com/ext/resources/files/2021/02-24-21-Vaccine.pdf?1614192077

Oliver S, et al. The Advisory Committee on Immunization Practices’ Interim Recommendation for Use of Janssen COVID-19 Vaccine – United States, February 2021. MMWR. Vol 70. March 2, 2021. cdc.gov/mmwr/volumes/70/wr/mm7009e4.htm?s_cid=mm7009e4_w

ACOG Practice Advisory, Vaccinating Pregnant and Lactating Patients Against COVID-19. acog.org/clinical/clinical-guidance/practice-advisory/articles/2020/12/vaccinating-pregnant-and- lactating-patients-against-covid-19 Accessed 3/8/21

CDC, Information about COVID-19 Vaccines for People with Allergies cdc.gov/coronavirus/2019-ncov/vaccines/recommendations/specific-groups/allergies.html Accessed 3/8/21