A major trial of a vaccine to protect against Covid-19 has launched in the UK – the third such trial in the country.
The jab – designed by the Belgian company Janssen – uses a genetically modified common cold virus to train the immune system.
It comes a week after preliminary results showed another vaccine offered 90% protection.
However, many types of vaccine are likely to be needed to end the pandemic.
The success of the vaccine developed by Pfizer and BioNTech has caused global excitement. However, it has not yet been approved for use and we still do not know how well it works in the elderly or how long immunity lasts.
The hunt for Covid vaccines continues as a different approach may yet be better, or better in some age groups, and one company will struggle to immunise the planet.
