Pfizer just released some early information about its COVID-19 vaccine, which appears to be successful at preventing symptoms of the infection. So far, Pfizer’s COVID-19 vaccine data has experts cautiously optimistic.
The announcement comes after an early analysis of data from a Phase 3 trial of the vaccine, which enrolled more than 43,000 participants and is still recruiting, according to a press release. Half of those participants received a placebo, and the other half got the vaccine candidate, which Pfizer is developing along with BioNTech.
Among all the participants, there have been 94 symptomatic cases of COVID-19. Based on how many participants got the vaccine and the infection versus those who received the placebo and developed the infection, the company concluded that its vaccine is over 90% effective at preventing symptomatic COVID-19 infections. It’s not clear exactly how many people in each group got the coronavirus or how effective the vaccine is at preventing asymptomatic infections.
Considering that the Food and Drug Administration (FDA) said it would consider approving a vaccine that was just 50% effective at preventing the infection or reducing the severity of its symptoms, these results are a pleasant surprise for public health experts. The results are “just extraordinary,” Anthony Fauci, M.D., director of the National Institute of Allergy and Infectious Diseases, told the AP. “Not very many people expected it would be as high as that.”
Other experts also say these results are encouraging but caution that we don’t know the full picture of how effective the vaccine really is. “That’s a big reduction in symptoms, but it’s not clear that this vaccine is effective at preventing infection altogether,” Angela Rasmussen, Ph.D., a virologist at Columbia University School of Public Health, said on Twitter. We also don’t know how well the vaccine works in people with underlying conditions—diabetes, asthma, heart disease, etc.—that might make them more vulnerable to severe COVID-19 complications, she said. And because the vaccine has only been studied for a few months, we don’t know how long its protection lasts, Ali Nouri, Ph.D., molecular biologist and president of the American Federation of Scientists, said on Twitter.
It’s also important to remember that the trial is ongoing and these results aren’t complete. “While the results are exciting, of course we will want to independently evaluate them,” Natalie E. Dean, Ph.D., assistant professor of biostatistics at the University of Florida, explained on Twitter. “Unlike treatments, promising data from vaccines do not immediately change standard of care. The vaccines will undergo a rigorous review process first which will play out over time.”
This is a time for “cautious optimism,” Rasmussen said. “This news does not mean we are on the verge of ‘ending the pandemic.’ If the data supports this, it’s a big milestone, but not the final milestone. There’s still a long road ahead. Manage your expectations.”
The Pfizer vaccine works by using mRNA technology to produce an immune response in people who haven’t been exposed to the virus. It’s not clear yet how effective the vaccine is in people who have been exposed to the coronavirus. Participants receive two doses of the vaccine given three weeks apart. Pfizer CEO Albert Bourla said he believed the vaccine would be made “available for free to all American citizens.”
Although Vice President Mike Pence quickly claimed credit for the vaccine’s apparent success on Twitter, development for vaccine was not part of the government’s Warp Speed project, Pfizer vice president Kathrin Jansen told the New York Times. However, the company is partnering with the government on scaling up the production and distribution of its vaccine once proven effective.
But even with an effective vaccine approved, the general public will still need to take other precautions to prevent the spread of COVID-19 while the vaccine rolls out, SELF explained previously. That includes wearing a mask in public, staying socially distanced, avoiding crowds, and frequently washing hands—especially with our rate of new cases every day so high heading into winter. An effective vaccine is one big step forward in our fight against the pandemic, but it’s still just one step.