Crystal Jones, 52, head of the Athens City Department of Health, loads syringes of the vaccine on the first day of Johnson and Johnson’s vaccine.

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LONDON – The European Union on Thursday approved the use of the one-off coronavirus vaccine developed by Johnson & Johnson and added another weapon to the armory to fight Covid-19.

The European drug regulator made its recommendation on Thursday, and the EU Commission issued formal approval later that day.

The vaccine has the added benefit of only requiring a single dose and can be stored in most standard refrigerators at temperatures of 2 to 8 degrees Celsius (or about 36 to 46 degrees Fahrenheit), making transportation and storage easier and cheaper makes.

Once delivery begins, the shot could add a lot to Europe’s difficult vaccination program and is the fourth to be approved by the EMA. Two-dose vaccines developed by Pfizer-BioNTech, Moderna and AstraZeneca, and Oxford University have also been approved.

While easier to distribute, the vaccine has been found not to be as effective as the Pfizer and Moderna shots in preventing Covid infection. However, the data shows that it offers an adequate level of protection: data from clinical trials from the United States have shown that J & J’s vaccine is 72% effective against moderate to severe Covid (although it has been found to be less effective in studies elsewhere which gives it an overall efficacy of 66% protection) compared to about 95% for the other two vaccines.

The speed at which the EU can introduce the J&J vaccine is not yet clear. The EU has ordered 200 million cans of the shot, with an option for an additional 200 million, Johnson & Johnson said in a statement last October.

However, it was reported on Wednesday that, like other vaccine suppliers in the EU (Pfizer-BioNTech and AstraZeneca), delivery of the J&J vaccine to the block may be slower than expected.

An unnamed EU official told Reuters that Johnson & Johnson had told the EU it was facing supply issues that could complicate plans to deliver 55 million doses of its vaccine to the block in the second quarter of the year. CNBC has contacted J&J for additional comments on the report and has yet to receive a response.

The European Commission, the EU’s executive branch, said on Wednesday that it had not been informed of any delays from J&J.

Another delay in vaccine supply would exacerbate the already lethargic introduction of vaccines in the EU, which has faced issues due to a slower ordering process than the UK and US, slower deliveries, bureaucracy and hesitant vaccines.

In the US, J&J has signed a contract with the US government to supply 100 million cans by the end of June. On Wednesday, the Biden government announced plans to buy an additional 100 million cans. The announcement came as the White House is working to ramp up production of the vaccine after learning earlier this year that the company had fallen behind in production.

Last week, Biden announced that pharmaceutical company Merck would help manufacture J & J’s Covid vaccine. Under the terms of the agreement, Merck will deploy two facilities in the US for J & J’s vaccine. One will make the vaccine and the other will provide “fill-finish” services when the vaccine is put into vials.

– CNBC’s Berkeley Lovelace Jr. contributed to this story.

Correction: This story has been updated to reflect the correct approval process within the EU.