Background document to the WHO Interim recommendations for use of Ad26.COV2.S (COVID-19) vaccine

This background document was prepared by the Strategic Advisory Group of Experts (SAGE) on Immunization Working Group on COVID-19 Vaccines to inform the discussions of SAGE at its 15 March 2021 meeting, which resulted in the issuance of the WHO interim recommendations for use of the Ad26.COV2.S (COVID-19) vaccine. Both the recommendations and the background document are available on the SAGE COVID-19 webpage: https://www.who.int/groups/strategic-advisory-group-of-experts-on-immunization/covid-19-materials. Declarations of interests were collected from all external contributors and assessed for any conflicts of interest. Summaries of the reported interests can be found on the SAGE meeting webpage and SAGE Covid-19 Working Group webpage. Context The Janssen vaccine is a recombinant vector vaccine that uses a human adenovirus to express the SARS-CoV-2 spike protein and is based on the Ad26 vector platform. The adenoviruses are a group of viruses that cause infections in the respiratory and gastrointestinal tracts; the adenovirus vector used in the experimental vaccine has been modified, so that it can no longer replicate in humans and cause illness. In developing the vaccine, Janssen employed the same vector used in the first dose of its prime–boost vaccine regimen against Ebola virus disease (Ad26 ZEBOV and MVN-BN-Filo). As of 31 December 2020, Ad26-based vaccines have been used to vaccinate 193 831 participants in clinical studies and vaccination programmes. These more than 193 000 participants included people from different age groups (elderly, adults, children and infants), individuals positive for human immunodeficiency virus (HIV), and pregnant and breastfeeding women, and the data show a favourable safety profile. Ad26-based vaccines elicit strong humoral immune responses with both neutralizing activity and non-neutralizing antibody functionalities, and cellular immune responses involving both CD8+ T cells and CD4+ T-cells, the latter with a predominantly Th1 phenotype, irrespective of the transgene encoded immunogens (1-4). Overall, these vaccines have been shown to have an acceptable clinical safety profile to date.Data taken into consideration are those included in the US Food and Drug Administration Vaccines and Related Biological Products Advisory Committee (VRBPAC) meeting documentation, available under the following links: www.fda.gov/media/146217/download and www.fda.gov/media/146218/download

Interim recommendations for the use of the Janssen Ad26.COV2.S (COVID-19) vaccine

Background This interim guidance has been developed on the basis of the advice issued by the Strategic Advisory Group of Experts (SAGE) on Immunization at its extraordinary meeting on 15 March 2021 (1). Declarations of interests were collected from all external contributors and assessed for any conflicts of interest. Summaries of the reported interests can be found on the SAGE meeting website and SAGE Working Group website. The guidance is based on the evidence summarized in the Background document on Janssen Ad26.COV2.S (COVID-19) vaccine and the Background paper on COVID-19 disease and vaccines. Both these documents are available on the SAGE COVID-19 webpage: www.who.int/groups/strategic-advisory-group-of-experts-on-immunization/covid-19-materials. Methods SAGE applies the principles of evidence-based medicine and has set in place a thorough methodological process for issuing and updating recommendations (2). A detailed description of the methodological processes as they apply to COVID-19 vaccines can be found in the SAGE evidence framework for COVID-19 vaccines (3). This framework contains guidance on considering data emerging from clinical trials in relation to the issuance of vaccine-specific evidence-based recommendations. General goal and strategy for the use of the Janssen Ad26.COV2.S (COVID-19) vaccine The COVID-19 pandemic has caused significant morbidity and mortality throughout the world, as well as major social, educational and economic disruptions. There is an urgent global need to develop effective and safe vaccines and to make them available at scale and equitably across all countries. Ad26.COV2.S vaccine against COVID-19 is a recombinant, replication-incompetent adenovirus serotype 26 (Ad26) vector encoding a full-length and stabilized SARS-CoV-2 spike protein. This vaccine does not contain adjuvants, preservatives, materials of animal origin, or fetal tissue. A single dose of Ad26.COV2.S has an efficacy of 66.9% (95% confidence interval (CI): 59.0,73.4) against symptomatic SARS-CoV-2 infection, 76.7% (95% CI: 54.6, 89.1) against severe COVID-19 disease after 14 days, and 85.4% (95% CI: 54.2, 96.9) after day 281. Vaccine efficacy against hospitalisations was 93.1% (95% CI: 72.7, 99.2). Vaccine efficacies were maintained across genders, age and ethnicities. At the time of analysis, the median follow-up was 58 days, with 55% of participants having had 2 months and more of follow-up. More detailed data on the efficacy and safety of this vaccine can be found in the Background document on Ad26.COV2.S. These data reviewed by WHO support the conclusion that the known and potential benefits of Ad26.COV2.S outweigh the known and potential risks. As sufficient vaccine supply will not be immediately available to immunize all who could benefit from it, countries are recommended to use the WHO Prioritization Roadmap (4) and the WHO Values Framework (5) as guidance for their prioritization of target groups. As long as vaccine supplies are very limited (stage I in the WHO Prioritization Roadmap), in settings with community transmission, the Roadmap recommends that priority be given initially to health workers and older people with and without comorbidities. As more vaccine becomes available, additional prioritygroups should be vaccinated as outlined in the WHO Prioritization Roadmap (4), taking into account national epidemiological data, vaccine-specific characteristics as outlined in product information approved by regulatory authorities, and other relevant considerations