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

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.

Posted: Mar 4, 2021 10:40 AM
Updated: Mar 4, 2021 12:19 PM

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.


FOX 55: Tracking the COVID-19 Vaccine

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.

CDC 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.

A
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.

Indiana Coronavirus Cases

Data is updated nightly.

Cases: 1011197

Reported Deaths: 16524
CountyCasesDeaths
Marion1359292129
Lake666181167
Allen58254802
Hamilton46498467
St. Joseph44559617
Elkhart36044510
Vanderburgh32333481
Tippecanoe28037260
Johnson25196446
Hendricks23960360
Porter22985367
Madison18820410
Clark18609253
Vigo17530303
Monroe15319200
LaPorte15230252
Delaware15127264
Howard14801290
Kosciusko12410149
Hancock11773176
Bartholomew11695180
Warrick11305189
Floyd11138215
Wayne11023253
Grant10131220
Morgan9506177
Boone8965116
Dubois8281131
Henry8252153
Dearborn823493
Noble8064106
Marshall7981135
Cass7556123
Lawrence7479172
Shelby7216119
Jackson700990
Gibson6614115
Harrison651892
Huntington6447100
Knox6427106
DeKalb6363100
Montgomery6293112
Miami595298
Putnam584179
Clinton579271
Whitley568455
Steuben566876
Wabash5363104
Jasper536180
Jefferson513297
Ripley501987
Adams483777
Daviess4684115
Scott439875
Greene427296
Clay426960
Wells426088
White420964
Decatur4177104
Fayette407387
Jennings390262
Posey377544
LaGrange361778
Washington360451
Randolph3476100
Spencer340743
Fountain336160
Sullivan330852
Starke319171
Owen315571
Fulton313468
Orange295064
Jay285546
Franklin266443
Perry265752
Rush263832
Carroll262434
Vermillion259854
Parke232029
Pike229643
Tipton229059
Blackford195042
Pulaski184657
Crawford160125
Newton159848
Benton151217
Brown147047
Martin139319
Switzerland135311
Warren121416
Union107216
Ohio84613
Unassigned0544

Ohio Coronavirus Cases

Data is updated nightly.

Cases: 1524169

Reported Deaths: 23955
CountyCasesDeaths
Franklin1646591696
Cuyahoga1468932459
Hamilton1056051431
Montgomery742551279
Summit620221111
Lucas56539917
Butler51696718
Stark468601064
Lorain35783585
Warren32903377
Mahoning30927693
Clermont28271330
Lake27179448
Delaware24263164
Licking24027294
Trumbull22993561
Fairfield22438247
Greene22414326
Medina22149313
Clark19920354
Richland18643292
Portage18073252
Wood17505224
Allen16054279
Miami15627306
Muskingum14890185
Columbiana14153274
Wayne13852271
Tuscarawas12777311
Marion12016180
Scioto11497162
Pickaway11386142
Erie10951184
Ross10614203
Ashtabula9809204
Lawrence9783153
Hancock9741155
Belmont9333209
Geauga9008157
Jefferson8600199
Huron8427143
Union822259
Washington8114144
Sandusky7875151
Athens779579
Knox7766144
Darke7695158
Seneca7405145
Ashland6993130
Auglaize681799
Shelby6540115
Brown640091
Crawford6292130
Defiance6241105
Mercer617893
Fulton605196
Highland602899
Guernsey596371
Madison595678
Logan594596
Clinton585193
Preble5730125
Putnam5354110
Williams530888
Perry519863
Champaign514273
Jackson512473
Ottawa490586
Coshocton488383
Morrow460558
Pike435067
Fayette430363
Hardin420780
Gallia419367
Adams417995
Van Wert374082
Henry366972
Holmes3653125
Hocking357582
Wyandot325262
Carroll304365
Paulding280747
Meigs267251
Monroe216254
Noble201247
Morgan194333
Harrison182646
Vinton167225
Unassigned05
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