(CNN) -- Moderna has finished accumulating data for a first analysis of its COVID-19 vaccine and expects to have an announcement on the vaccine's efficacy by the end of the month, the company said in a statement Wednesday.
Pfizer announced Monday that its coronavirus vaccine is more than 90% effective.
Moderna, which has its headquarters in Cambridge, is conducting a clinical trial of 30,000 participants, with half receiving the vaccine and half receiving a placebo, which is a shot of saline that does nothing.
In order for Moderna's vaccine to be considered for authorization by the US Food and Drug Administration, at least 53 study participants needed to become ill with Covid-19.
The trial hit that 53 mark Wednesday, but Moderna doesn't know if the participants who became ill received the vaccine or the placebo. The company is now preparing data to send to the trial's Data and Safety Monitoring Board, an independent panel of experts.
That board will look to see how many of the participants who became ill received the vaccine and how many received the placebo. If a statistically significant number received the placebo, that means the vaccine is effective against the virus.
Moderna thinks the board will share efficacy results before the end of the month. And, since cases are rapidly rising in the US, more than 53 participants will become ill with Covid-19 by the time the announcement is made.
Moderna and Pfizer use messenger RNA for their vaccines. Dr. Anthony Fauci has said Pfizer's promising outcomes are good news for Moderna, too.
"Moderna has an almost identical mRNA," Fauci told Financial Times correspondent Hannah Kuchler in an interview posted Wednesday. "We hope we're going to see a similar kind of result from Moderna. If we do, then we'll have two vaccines in play."
Pfizer's results from the never-before-approved mRNA technology were better than expected, said Fauci, director of the National Institute of Allergy and Infectious Diseases.
"I really quite honestly did not expect that we would have a result as striking as this -- more than 90%, close to 95% efficacy -- on the first vaccine that went through the gate," he said.
Moderna is working with NIAID to develop its vaccine.
"I would really be surprised if we did not see a high degree of efficacy," Fauci said. "You know it may not be 95%, it might be 90 or 96 or 89, but it's going to be up there. I'm fairly certain it's going to be up there."
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