Health worker filling a vaccine syringePhoto: Guillermo Legaria (Getty Images)

Johnson & Johnson published numbers today of their Phase 3 clinical trials (the final step before applying for an emergency permit) and it looks like we will soon have a third viable COVID-19 vaccine in the US.

This vaccine is a little different from the other two. Those from Pfizer / BioNTech and Moderna are both mRNA vaccineswhich require two cans and must be stored at freezing temperatures or in special ultra-cold packaging. The Johnson & Johnson vaccine, like most other vaccines available at a pharmacy or doctor’s office, can be stored at refrigerator temperature. And it only requires one dose.

Illustration for article titled What is Different About the Johnson Johnson Vaccine?

The new vaccine was found to be 85% effective in preventing serious COVID-19 illnesses, and in the US it was 72% effective in preventing “moderate to severe” illnesses, according to the press release. In other countries, the effectiveness appeared to be less, except for 56% in South Africa, where the most common strain of COVID is a regarding the variant. It is not yet clear whether the difference is due to the variant or to some other factor or combination of factors.

If you are wondering about the difference between “moderate” and “severe” COVID-19, the press release includes the following definitions:

In the study, the definition of severe COVID-19 disease included laboratory-confirmed SARS-CoV-2 and one or more of the following symptoms: signs of severe systemic illness, ICU admission, respiratory failure, shock, organ failure, or death, among others Factors. Moderate COVID-19 disease was defined as laboratory-confirmed SARS-CoV-2 and one or more of the following symptoms: signs of pneumonia, deep vein thrombosis, shortness of breath, or abnormal blood oxygen saturation above 93%, abnormal breathing rate (≥ 20) ); or two or more systemic symptoms suggestive of COVID-19.

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None of the people who received the vaccine experienced hospitalizations or deaths from COVID once they were 28 days after their first and only dose.

Even if this vaccine turns out to be less effective than the mRNA vaccines overall, the fact that it only takes one dose and can be dispensed at refrigerator temperature may mean it can reach – and get to them – more people faster than these vaccines.