Johnson & Johnson vaccine: How effective is UK’s new one-dose jab?
The UK has ordered 20 million doses of the vaccine that will be available by the end of the year
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Your support makes all the difference.The Johnson & Johnson coronavirus vaccine is to be first single-dose jab rolled out during the pandemic in the UK.
The Medicines and Healthcare products Regulatory Agency (MHRA) approved the Johnson & Johnson jab for use on Friday, making it the now the fourth Covid-19 vaccine that will be available across the country. But how does it work, and how effective is it? Here’s what you need to know about the new one-dose jab:
What kind of vaccine is it?
The jab, developed by Johnson & Johnson’s pharmaceutical arm, Janssen, is an adenovirus vaccine. Like the AstraZeneca jab, it is based on a weakened version of the common cold virus. By injecting this adenovirus, it signals instructions to the body’s defence systems, and triggers an immune response to begin producing antibodies.
Pfizer and Moderna are both mRNA vaccines, and use a different mechanism which contain genetic instructions for cells in the body to make the Covid-19 ‘spike protein’ which can then be recognised by the immune system. The immune system then builds a response against the spike protein, and is able to fight the virus if encountered in the future.
How effective is it?
The Johnson & Johnson jab has been shown to be 67 per cent effective in preventing moderate to severe Covid-19, and 85 per cent effective in preventing hospitalisation.
Will it work against different variants?
Johnson & Johnson has said the vaccine works across multiple variants of Covid-19. However, the clinical trial data from South Africa found that it offered a lower level of protection against the mutant of the virus that has become dominant, offering 57 per cent protection against moderate to severe infection.
Are there risks of blood clots?
In the US, more than eight million people received the Johnson & Johnson jab. Of those about sixteen people experienced rare blood clots in the days after receiving the vaccine, the majority of whom were women.
The European Medicines Agency (EMA) has noted a “possible link” between the jab and very rare blood clots, but determined that the benefits of the vaccine “outweigh the risks of side effects.”
How much will the UK get?
The government expects to receive 20 million doses towards the end of the year, adding to the country’s biggest vaccination programme in history. Originally the UK’s vaccine taskforce had ordered 30 million doses, but based on the vaccine rollout to date —73 per cent of adults have received one dose of a vaccine, and 46 per cent are fully vaccinated — the government has decided to amend its order.
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