A Quick Guide to the Latest Vaccine News

A reading list to understand the results from Pfizer and Moderna, and what comes next

Alexandra Sifferlin
Medium Coronavirus Blog
4 min readNov 18, 2020


Credit: Justin Tallis / Getty Images

Pfizer and BioNTech announced this morning that they will be submitting their Covid-19 vaccine data to the Food and Drug Administration (FDA) and that their full results show 95% efficacy. This includes 94% efficacy in adults over the age of 65, who are at a higher risk of severe Covid-19. The two companies, which have partnered on the vaccine, say they will submit to the FDA for an emergency use authorization “within days.” They will also submit to regulatory agencies around the world.

The news comes after Moderna announced on Monday that preliminary results from a large late-stage trial suggest 94.5% efficacy for its vaccine, which uses a new kind of technology similar to Pfizer’s. They are also expected to submit for emergency use authorization soon.

Pfizer reported 170 cases of Covid-19; 162 of those cases occurred in the placebo group and only eight in the group that got the two-dose vaccine. Among 10 cases of more severe Covid-19, nine were in the placebo group. “An important finding,” Stat reports, “which suggests the vaccine prevents not only mild cases, but the type of serious disease that leads patients to die or be hospitalized.” The company says there were no serious side effects and that the side effects that occurred in more than 2% of people they followed were fatigue and headache.

If approved for emergency use, a vaccine can begin distribution to people at a high risk for infection, like health care workers. It’s unknown when a vaccine would be available for more people, but it’s likely into 2021. As the New York Times reports, this is what Pfizer is submitting to the FDA:

In addition to the results of its clinical trial, Pfizer said it was ready to submit to the FDA two months of safety data that the agency had recommended, as well as detailed manufacturing records showing the company can consistently produce high-quality batches of its product. The FDA will review the data and ask an outside panel of vaccine experts to weigh in on the application, a process that could take weeks.

There are still questions about how well various vaccines will work against severe forms of Covid-19, though the recent Pfizer data is promising. It’s also unclear how long the effectiveness will last. Whether people will need to get vaccinated multiple times against Covid-19 during their lifetime is unknown.

The vaccines have been developed quickly (as expected in a pandemic), and are not small studies. The phase 3 trial of Pfizer has over 43,000 people, and Moderna’s has 30,000. There are also other vaccines in development. A vaccine—and likely more than one—on the horizon is hopeful news, especially for health workers currently dealing with rising cases and hospitalizations throughout the United States.

A bleak reason for some of the vaccine speed is that the U.S. is currently surging in Covid-19 cases, which, as the New York Times reports, means companies can more quickly tell if their vaccine is working.

“The surging virus has already allowed Pfizer and Moderna to accelerate the testing of their vaccines, which appear to be very effective at preventing Covid-19…

In the coming weeks and months, the worsening pandemic could make results from other closely watched trials, such as one for a vaccine developed by Johnson & Johnson and another by AstraZeneca and the University of Oxford, available sooner and with greater statistical power.

The fast-growing pandemic could also speed up trials of treatments for Covid-19.”

The high effectiveness reported by these vaccines has surpassed expectations. Anthony Fauci, MD, director of the National Institute of Allergy and Infectious Diseases, has said of the Moderna vaccine: “I had been saying I would be satisfied with a 75% effective vaccine. Aspirationally, you would like to see 90, 95%, but I wasn’t expecting it. I thought we’d be good, but 94.5% is very impressive.”

I recommend the following stories to learn more about how the vaccine priority list is decided, and how the vaccine will be distributed.



Alexandra Sifferlin
Medium Coronavirus Blog

Health and science journalist. Former editor of Medium’s Covid-19 Blog and deputy editor at Elemental. TIME Magazine writer before that