In a year when every turn of the calendar brought more bad news, the recent announcements that two coronavirus vaccines are more than 90% effective is a rare shot of good news.

Moderna and Pfizer both revealed promising results this month for the mRNA vaccine candidates both companies are developing.

Moderna, which worked with scientists from the National Institutes of Health, said Monday its vaccine was 94.5% effective against SARS-CoV-2 and the disease it causes, COVID-19. Last week Pfizer and BioNTech said preliminary results show its COVID-19 vaccine is 95% effective.

For this week’s FAQ Friday, we answer questions about COVID-19 vaccines, the findings of which have not yet been peer-reviewed.

When will the vaccines be available?

Pfizer said Friday it applied to the Food and Drug Administration (FDA) for emergency authorization for its vaccine. The FDA and an independent committee will then make a recommendation. Moderna is expected to do the same soon.

The vaccines could be approved and ready for distribution sometime in December, said Alex Azar, the Health and Human Services Secretary.


Both federal and state officials say that the first people in line to be vaccinated are front-line health care workers, first-responders, people in long-term care facilities and others considered to be high-risk.

The general public could begin receiving the two-shot vaccinations in the spring or summer of 2021.

How long would COVID-19 vaccines protect against the disease?

The early data for the two vaccines show they work better than many had hoped. What isn’t known is how long the vaccines protect people. That knowledge will only come with time.

A recent study, which has yet to be peer-reviewed, showed immunity to COVID-19 could last years. The immune-memory study shows that eight months after infection, most people have enough immune cells to mount a defense against the virus.

“That amount of memory would likely prevent the vast majority of people from getting hospitalized disease, severe disease, for many years,” Shane Crotty, one of the leads on the study and a virologist at the La Jolla Institute of Immunology, told The New York Times.

If the body can produce a long-lasting immunity to the virus, that bodes well for vaccines and could mean that it won’t be like the flu vaccine that has to be developed every year to keep up with the quickly mutating virus.


What is mRNA technology?

While mRNA technology has been around for decades, it has rushed to the front of the pack in the race to create a vaccine for a virus that disease scientists didn’t know about at this time last year.

Vaccine development normally takes years and is often done by using dead or inactive parts of a virus.

An mRNA vaccine introduces genetic code for viral antigens that could teach the body’s immune system to respond to the virus.

“This is the greatest science experiment in vaccinology that’s ever been done,” Andrew Ward, a structural biologist at the Scripps Research Institute in San Diego, told The Washington Post. “It’s literally testing all the different technologies, and it’s going to be cool to see how this all shakes out.”

If you have a question you haven’t seen addressed in The Seattle Times’ coverage, ask it at or via the form below.

Do you have questions about the coronavirus that causes COVID-19?

Ask in the form below and we’ll dig for answers. If you’re using a mobile device and can’t see the form on this page, ask your question here. If you have specific medical questions, please contact your doctor.

More on the COVID-19 pandemic