Three US studies suggest Covid-19 vaccines offer strong protection against hospitalisation and death, even in the face of the highly transmissible Delta variant, but vaccine protection appears to be waning among older populations, especially among those 75 and older, reports Reuters.

US data on hospitalisation from nine states during the period when the Delta variant was dominant also suggests that the Moderna Inc vaccine was more effective at preventing hospitalisations among individuals of all ages than vaccines from BioNTech/Pfizer Inc or Johnson & Johnson (J&J).

In that study of more than 32,000 visits to urgent care centre, emergency rooms and hospitals, Moderna's vaccine was 95 per cent effective at preventing hospitalisation compared with 80pc for Pfizer and 60pc for J&J.

Overall, the findings, released on Friday in the US Centres for Disease Control and Prevention's weekly report on death and disease show that vaccines continue to offer strong protection from Covid-19.