Janssen/J&J vaccine against COVID-19 is approved in the EU

Simon Collins, HIV i-Base

On 11 March 2021, the European Union authorised the COVID-19 vaccine developed by Janssen/J&J. [1]

Approval is based on results that include an international phase 3 study (ENSEMBE 1).

The was a double-blind that equally randomised 44,000 adults (age 18 years and older) in the United States, South Africa and Latin American countries to either a single dose of the Janssen vaccine or placebo.

Results included a 67% reduced risk of symptomatic COVID-19 two weeks: 116 vs 348, in active vs placebo groups respectively.

Side effects were usually mild or moderate and cleared within a couple of days after vaccination. The most common were pain at the injection site, headache, tiredness, muscle pain and nausea.


A date for approval in the UK is not yet available, but news on EU approval was also with notice that access in Europe was not expected until April.

The US FDA approved this vaccine a couple of weeks earlier, on 27 February 2021.

The ENSEMBLE 2 study using a double dose vaccine schedule that includes UK sites is still ongoing. [3]


  1. EMA recommends COVID-19 Vaccine Janssen for authorisation in the EU. (11 March 2021).
  2. FDA. Janssen COVID vaccine.
  3. A Study of Ad26.COV2.S for the Prevention of SARS-CoV-2-mediated COVID-19 in Adults (ENSEMBLE 2).

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