Two doses of Pfizer and Moderna’s Covid-19 vaccine are necessary, officials say, but questions still linger

Mar 4, 2021, 5:39 AM
Employees will be requires to get completely vaccinated or get test weekly for Covid-19. Credit: Ap...
Employees will be requires to get completely vaccinated or get test weekly for Covid-19. Credit: Apu Gomes/AFP/Getty Images

    (CNN) — The United States is holding firm to the strategy to administer two doses of the Moderna and Pfizer/BioNTech Covid-19 vaccines a few weeks apart. Still, the idea of expanding the supply by dispensing only one dose hasn’t faded away.

The Trump administration’s surgeon general, Dr. Jerome Adams, said in a tweet on Tuesday that the good protection available with one shot “is better than great protection for a few.”

He later clarified with a second tweet that he wasn’t recommending that it was 100% the way to go, but that it was worth “giving states the flexibility to try it.”

Although 80.5 million vaccine doses have been administered in the United States and the single-dose Johnson & Johnson vaccine is entering the US supply, demand still far outpaces the number of vaccines available.

That has not swayed vaccine makers, the US Food and Drug Administration or the CDC to shift toward single doses to cover more people sooner.

Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, told CNN’s Erin Burnett on Wednesday that Adams’ tweets were not accounting for the impact of virus variants, which can decrease the amount of protection from vaccines.

“First of all, I love Jerome Adams. He’s really a terrific guy. We worked so well together during the Trump administration,” Fauci said. “I think he’s incorrect on this.”

By going with just one dose, “you’re at a very tenuous level. Good enough to do protection, but if you diminish it by fivefold, you fall off the chart of protection.”

The mRNA vaccines were authorized for use in the US based on clinical trial data that shows two doses of the vaccines taken a few weeks apart are about 95% effective at preventing symptomatic infection. Clinical trials for both vaccines show that the second dose gives a big boost to protective antibodies.

DC guidelines continue to advise two doses of the Pfizer and Moderna vaccines, and experts at the CDC’s Advisory Committee on Immunization Practices (ACIP) meeting on Monday said there’s insufficient scientific evidence to support a vaccination strategy that would delay a second dose or eliminate it all together.

“Five studies have shown that postponing the second mRNA dose may leave some people less protected against the SARS-Cov-2 variants,” the CDC’s Dr. Heather Scobie said at the ACIP meeting.

Fauci told The Washington Post this week there are “risks on either side” of switching to a single dose or sticking with the two. Experts worry that a single dose strategy could lead to more coronavirus variants, and create more doubt and confusion during an already complicated vaccine rollout.

“We’re telling people [two shots] is what you should do … and then we say, ‘Oops, we changed our mind’?” Fauci said. “I think that would be a messaging challenge, to say the least.”

That doesn’t mean there won’t be more dosing changes to come.

Around the world, researchers are looking into the efficacy of single doses of mRNA vaccines. Meanwhile, the J&J vaccine — currently authorized as a single-dose vaccine — is also being trialed as two doses to see if it will provide more protection.

Studying single doses

Some countries are already employing single-dose strategies as a way to stretch their supply and offer some protection to more people.

Since late December, the UK has not told people to skip the second shot, but it has delayed the second doses of the Pfizer/BioNTech vaccine to prioritize first doses. The delay meant that the interval between doses could be extended up to 12 weeks instead of about three.

In reaction to the vaccine schedule change, Pfizer said at the time that it did not test its vaccine this way.

“Pfizer and BioNTech’s Phase 3 study for the Covid-19 vaccine was designed to evaluate the vaccine’s safety and efficacy following a 2-dose schedule, separated by 21 days,” Pfizer said. “There are no data to demonstrate that protection after the first dose is sustained after 21 days.”

There has been some research that suggests the Pfizer/BioNTech vaccine provides some protection after one dose.

Researchers at Israel’s largest hospital looked at what happened after 7,000 staff got vaccinated with the first dose of the Pfizer/BioNTech vaccine. By the second to fourth week after they got the first shot, rates of symptomatic infection were down by 85%.

However, it’s still not clear how long this protection would last. Also, the study noted the people who were vaccinated were “younger and healthier” and may not reflect the broader population.

There’s some research, too, that suggests one dose might be enough for people with a previous infection. Two papers published last week in The Lancet found that just one dose of Pfizer/BioNTech’s coronavirus vaccine can induce a strong enough immune response in people who have already had the coronavirus that it could protect from future infection. France has already recommended that people previously infection get only one dose.

nd in a letter sent to the New England Journal of Medicine in February, Canadian researchers went through the documents Pfizer/BioNTech submitted for the emergency use authorization last year and concluded that a single dose is still at least 90% effective.

“With such a highly protective first dose, the benefits derived from a scarce supply of vaccine could be maximized by deferring second doses until all priority group members are offered at least one dose,” they added.

But, they noted it’s still unclear how long protection lasts with just one dose.

™ & © 2021 Cable News Network, Inc., a WarnerMedia Company. All rights reserved.

How To Prevent the Spread of COVID-19 Coronavirus

COVID-19 coronaviruses transmitted from person to person. It is a virus that is similar to the common cold and the flu. So, to prevent it from spreading:

  • Wash hands frequently and thoroughly, with soap and water, for at least 20 seconds.
  • Wear a mask.
  • Don’t touch your face.
  • Keep children and those with compromised immune systems away from someone who is coughing or sneezing (in this instance, at least six feet)
  • If there is an outbreak near you, practice social distancing (stay at home, instead of going to the movies, sports events, or other activities.)
  • Get a flu shot.

Local resources

KSL Coronavirus Q&A

Utah’s Coronavirus Information

Utah State Board of Education

Utah Hospital Association

The Church of Jesus Christ of Latter-day Saints

Utah Coronavirus Information Line – 1-800-456-7707

National Resources

Centers for Disease Control and Prevention

Commonly asked questions, World Health Organization

Cases in the United States


Today’s Top Stories


First Lady Utah vaccine mandate...
Priscilla Alvarez, CNN

Biden touts climate package at Global Citizen Festival

President Joe Biden and first lady Jill Biden addressed the Global Citizen Festival early Sunday, underscoring the administration's commitment to climate action
15 hours ago
(Photo courtesy of Salt_Verse on Twitter)...
Rachel Metz, CNN Business

This guy is using AI to make movies — and you can help decide what happens next

"Salt" resembles many science-fiction films from the '70s and early '80s. The way it was created points to what could be a new frontier for making movies.
15 hours ago
The short range missile was fired early Sunday morning local time from the Taechon area of North Py...
Yoonjung Seo, Junko Ogura and Larry Register, CNN

North Korea fires ballistic missile into waters off east coast of Korean peninsula

North Korea has fired a ballistic missile into the waters off the east coast of the Korean peninsula, according to officials in both South Korea and Japan.
2 days ago
WWE Essential...
Zoe Sottile, CNN

John Cena breaks Make-A-Wish record after granting 650 wishes

Actor, wrestling legend, and perpetual meme subject John Cena has completed a new accomplishment: breaking the world record for most wishes granted through the Make-A-Wish Foundation.
2 days ago
US Secretary of State Antony Blinken and Chinese Foreign Minister Wang Yi "had a direct and honest ...
Jennifer Hansler, CNN

Blinken and Chinese Foreign Minister have ‘direct and honest exchange’ on Taiwan

Leaders from the United States and China have honest and direct exchange about Taiwan.
2 days ago
Nancy Galarza looks at the damage that Hurricane Fiona inflicted on her community, which remained c...
Aya Elamroussi, Theresa Waldrop and Christina Maxouris, CNN

Hurricane Fiona likely to be ‘extreme weather event’ as it barrels toward eastern Canada, forecasters warn

Hurricane Fiona has weakened to Category 3 and will likely be extreme weather event as it approaches Canada.
2 days ago

Sponsored Articles

a worker with a drill in an orange helmet installs a door in the house...
Price's Guaranteed Doors

Home improvement tip: Increase the value of your home by weatherproofing doors

Make sure your home is comfortable before the winter! Seasonal maintenance keeps your home up to date. Read our tips on weatherproofing doors.
Curb Appeal...
Price's Guaranteed Doors

How to have the best of both worlds for your house | Home security and curb appeal

Protect your home and improve its curb appeal with the latest security solutions like beautiful garage doors and increased security systems.
A paper reading IRS, internal revenue service is pictured...
Jordan Wilcox

The best strategies for dealing with IRS tax harassment | You have options!

Learn how to deal with IRS tax harassment. This guide will teach you how to stop IRS phone calls and letters, and how to handle an IRS audit.
spend a day at Bear Lake...
Bear Lake Convention and Visitors Bureau

You’ll love spending the day at Bear Lake | How to spend a day at Bear Lake

Bear Lake is a place that needs to be experienced. Spend a day at Bear Lake.
Prescription opioids can be disposed of during National Prescription Take Back Day...
Know Your Script

Prescription opioid misuse | How to protect your family from the opioid epidemic

Studies have shown that prescription opioid misuse has increased since COVID-19. So what do you need to know about these opioids?
national heart month...
Intermountain Healthcare

National Heart Month: 5 Lifestyle Changes to Make Today to Keep You Heart Healthy

Heart disease is the leading cause of death for both men and women. One person dies every 36 seconds in the United States from cardiovascular disease
Two doses of Pfizer and Moderna’s Covid-19 vaccine are necessary, officials say, but questions still linger