Johnson & Johnson vaccine effectiveness: How does jab compare to AstraZeneca and Moderna?

The UK has approved the use of a fourth coronavirus vaccine today, the Johnson & Johnson jab. This vaccine differs from those already available as it is a single-dose vaccine, rather than requiring two separate shots. The vaccine was developed by Johnson & Johnson’s pharmaceutical arm, Janssen.

Announcing the Medicines and Healthcare products Regulatory Agency (MHRA) had approved the safety of the jab, Health Secretary Matt Hancock said: “This is a further boost to the UK’s hugely successful vaccination programme, which has already saved over 13,000 lives, and means that we now have four safe and effective vaccines approved to help protect people from this awful virus.

“As Janssen is a single-dose vaccine, it will play an important role in the months to come as we redouble our efforts to encourage everyone to get their jabs and potentially begin a booster programme later this year.”

The UK has placed an order for 20 million doses of the vaccine, which may be used for people in harder to reach areas as with just one dose needed, requesting a second appointment would not be needed.

So what do we know about the Johnson & Johnson vaccine?

Read More: Johnson & Johnson vaccine: When will newly approved jab be rolled out?

What is the Johnson & Johnson vaccine?

The Johnson & Johnson vaccine is an adenovirus vaccine.

Vaccines of this type are based on weakened versions of adenoviruses.

Adenoviruses are a group of viruses that typically infect membranes of the eyes, respiratory tract, urinary tract, intestines and nervous system, and include the common cold.

Like the Oxford/AstraZeneca jab, the J&J vaccine uses viral vector technology where a modified version of a different virus is used to deliver instructions to the body’s cells.

This then triggers the immune system to begin producing antibodies.

How effective is the Johnson & Johnson vaccine?

The J&J vaccine has been shown to be 67 percent effective overall at preventing moderate to severe Covid-19.

Studies have suggested the jab also offers complete protection from admission to hospital and death.

Johnson & Johnson has said the vaccine works across multiple variants of coronavirus.

In a clinical trial involving 43,783 people, published earlier this year, the level of protection against moderate to severe Covid-19 infection was found to be 72 percent in the United States arm of the trial.

It was 66 percent in the Latin American arm of the trial, and 57 percent in the South African arm, where a mutant variant of the virus has been dominating.

The overall efficacy from these trials combined was 67 percent.

Comparatively, the Moderna vaccine – which requires two doses – was found to be 50.8 percent effective up to 14 days after the first dose.

After two weeks, effectiveness was around 92.1 percent.

Following the second dose of Moderna your body will reach full immunity in around two weeks.

After this, the vaccine is approximately 94.1 percent effective.

Elsewhere, a study by the Korea Disease Control and Prevention Agency (KDCA) showed the Pfizer vaccine was 89.7 percent effective in preventing infection at least two weeks after a first dose was given.

The same data found the AstraZeneca shot was 86.0 percent effective.

The study’s results are based on more than 3.5 million people in South Korea aged 60 and older for two months from February 26.

It included 521,133 people who received a first dose of either Pfizer or AstraZeneca shot.

What about risk of blood clots after the Johnson & Johnson vaccine?

The MHRA is believed to have stalled early approval of the vaccine after concerns were raised in the US about a link to extremely rare blood clots.

The clots are similar to those seen in a very small proportion of people having the Oxford/AstraZeneca jab.

In April, the European Medicines Agency said a warning about unusual blood clots with low blood platelet count should be added to the product information for the vaccine.

This followed eight cases of blood clots in more than seven million people vaccinated in the US.


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