The one-dose Janssen vaccine is back in the news after Tanaiste Leo Varadkar revealed his "profound concern" for those who receive the vaccine just a few months ago.
This warning comes on the back of a surge in Covid-19 cases that has led to a massive strain on the health service with 598 people being treated in hospital for Covid-19, including 132 in ICU.
In a recent US study, it was found that the effectiveness of the J&J vaccine against infection dropped to 13.1 per cent over eight months.
Those in the age cohort of 18-34 were eligible to receive the one-dose Janssen vaccine back in the summer. In total, over 155,000 people received a J&J jab. However, in July 2021 the Government stopped ordering Janssen as Pfizer was the preferred option.
The main trial of the Janssen vaccine showed that it had an efficacy of 67% against symptomatic, moderate and severe Covid-19 infection.
28 days after vaccination, the J&J vaccine was found to have an efficacy of 85.4% against severe disease and 93.1% against hospitalisation.
However, the Tanaiste has said that immunity for those who received the Janssen vaccine may be as low as 20% just a few months after receiving the jab.
Appearing on Today with Claire Byrne, the Tanaiste said: "I have profound concern for them because there's very strong evidence now that immunity from that particular vaccine falls to as low as 20%."
As the booster campaign continues to increase its rollout, those who received a J&J vaccine will receive an mRNA vaccine for the booster shot, most likely Pfizer.
The National Immunisation Advisory Committee (Niac) has recommended a three-month gap in between getting the Janssen vaccine and the Pfizer booster shot.
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