Ongoing trial shows Pfizer Covid-19 vaccine remains highly effective after six months

The ongoing Phase 3 clinical trial of Pfizer/BioNTech's coronavirus vaccine confirms its protection remains high for at least six months after the second dos...

Posted: Apr 1, 2021 9:32 AM
Updated: Apr 1, 2021 3:30 PM

The ongoing Phase 3 clinical trial of Pfizer/BioNTech's coronavirus vaccine confirms its protection remains high for at least six months after the second dose, the companies said Thursday.

Protection likely lasts even longer than that, vaccine experts say, but they say having data showing good protection six months after people were vaccinated is good news.

The vaccine remains more than 91% effective against disease with any symptoms for six months, the companies said in a statement. And it appeared to be fully effective against the worrying B.1.351 variant of the virus, which is the dominant strain circulating in South Africa and which researchers feared had evolved to evade the protection of vaccines, the companies said.

'The vaccine was 100% effective against severe disease as defined by the U.S. Centers for Disease Control and Prevention (CDC), and 95.3% effective against severe COVID-19 as defined by the U.S. Food and Drug Administration (FDA),' Pfizer and BioNTech said in a joint statement.

The findings indicate protection will last even longer than six months, vaccine experts said.

'The information coming from Pfizer-BioNTech is good news with evidence that those enrolled in the clinical trials last year are still protected. So we know that immunity will not be short-lived,' Dr. Peter Hotez, a vaccine expert and dean of the school of tropical medicine at Baylor College of Medicine, told CNN.

'Hopefully the protection might last years, but we won't know until we know.'

On Wednesday, the companies said a small trial of volunteers aged 12 to 15 showed 100% efficacy in that age group.

'These data confirm the favorable efficacy and safety profile of our vaccine and position us to submit a Biologics License Application to the U.S. FDA,' Albert Bourla, Pfizer's chairman and chief executive officer, said in a statement. A BLA is an application for full approval. The vaccine currently has emergency use authorization, EUA, which falls short of full approval.

'The high vaccine efficacy observed through up to six months following a second dose and against the variant prevalent in South Africa provides further confidence in our vaccine's overall effectiveness.'

Dr. Anthony Fauci, Director of the National Institute of Allergy and Infectious Diseases, agreed that protection from these vaccines is likely to last longer than six months.

'They know at six months it's clearly there. It more than likely will be even longer. Time will tell,' Fauci told CNN.

Studies of people's immune responses after being vaccinated against coronavirus show they produce high levels of antibodies and then, after a few weeks, the body produces immune cells, known as B cells, that continue to produce fresh protective antibodies, Fauci noted. That makes for lasting immune protection.

Pfizer has been studying the vaccine in more than 46,000 volunteers and has noted 927 cases of confirmed Covid-19.

'From the 927 confirmed symptomatic cases of COVID-19 in the trial, 850 cases of COVID-19 were in the placebo group and 77 cases were in the BNT162b2 group, corresponding to vaccine efficacy of 91.3%,' it said.

'In South Africa, where the B.1.351 lineage is prevalent and 800 participants were enrolled, nine cases of COVID-19 were observed, all in the placebo group, indicating vaccine efficacy of 100%,' the company said.

'Vaccine safety has now been evaluated in more than 44,000 participants aged 16 years and older with more than 12,000 vaccinated participants having at least six months of follow-up after their second dose.'

Dr. Scott Hensley, an immunologist at the University of Pennsylvania who has studied mRNA vaccines like Pfizer's and Moderna's for years, says the strong protection after six months means the vaccines are likely to protect people for even longer -- years, possibly.

'The vaccine elicits such high levels of antibodies that even when confronted with a variant ... there's still meaningful protection,' Hensley told CNN.

'These mRNA vaccines -- it really seems the level of antibodies they elicit are so high, they are persistent. And the combination of having very high levels of antibodies and persistent levels of protection are the recipe for a very long level of protection against these variants,' Hensley added.

'I would not be surprised if this is a vaccine that we only get once.'

Both Pfizer and Moderna use a technology called messenger RNA or mRNA delivery as the basis of their vaccines. The approach has been tested against other viruses and studies in animals and people show they stimulate a strong and broad immune response.

The companies have received emergency use authorization from the US Food and Drug Administration and Pfizer says it will now seek full approval. As part of the process, they both must continue their clinical trials for two years and will continue to report safety and efficacy data as they get it.

Mississippi Coronavirus Cases

Data is updated nightly.

Cases: 482902

Reported Deaths: 9425
CountyCasesDeaths
Harrison33063488
Hinds31021589
DeSoto30610358
Jackson23687348
Rankin21340370
Lee14909220
Madison14166271
Jones13404227
Forrest13160240
Lauderdale11601305
Lowndes10443176
Lamar10214130
Pearl River9098221
Lafayette8241137
Hancock7514112
Washington7102150
Oktibbeha6964124
Monroe6514164
Neshoba6475201
Warren6464164
Pontotoc630393
Panola6250126
Marshall6126123
Bolivar6115144
Union574186
Pike5613136
Alcorn537290
Lincoln5303131
George471472
Scott459196
Leflore4476140
Prentiss446779
Tippah446480
Itawamba4444100
Adams4416116
Tate4394101
Simpson4335112
Wayne433066
Copiah431787
Yazoo423386
Covington415792
Sunflower4148104
Marion4099104
Leake397586
Coahoma3957100
Newton370875
Grenada3556104
Stone350860
Tishomingo336289
Attala325387
Jasper314162
Winston304691
Clay296473
Chickasaw287065
Clarke282190
Calhoun266141
Holmes262187
Smith250649
Yalobusha221047
Tallahatchie220450
Walthall211058
Greene209045
Lawrence206833
Perry199953
Amite198452
Webster196542
Noxubee178939
Montgomery172454
Jefferson Davis168342
Carroll162137
Tunica153334
Benton142535
Kemper138640
Choctaw127026
Claiborne126834
Humphreys126637
Franklin116728
Quitman103926
Wilkinson101936
Jefferson91333
Sharkey63020
Issaquena1926
Unassigned00

Alabama Coronavirus Cases

Cases: 784484

Reported Deaths: 13921
CountyCasesDeaths
Jefferson1111691760
Mobile707171225
Madison49549625
Baldwin36108489
Shelby36062314
Tuscaloosa33661547
Montgomery33066676
Lee22407219
Calhoun21041405
Morgan19734334
Etowah19001459
Marshall17619274
Houston16697382
St. Clair15361303
Cullman14506257
Limestone14505187
Elmore14387260
Lauderdale13436280
Talladega12855234
DeKalb12140236
Walker10524329
Blount9649156
Autauga9642137
Jackson9325156
Coffee8793175
Dale8529172
Colbert8482182
Tallapoosa6616177
Escambia6553120
Covington6420165
Chilton6342143
Russell602455
Franklin5758101
Chambers5370133
Marion4769117
Dallas4676187
Pike460096
Clarke459878
Geneva4371116
Winston422994
Lawrence4107108
Bibb407380
Barbour343270
Marengo325683
Monroe317152
Butler316490
Randolph304456
Pickens301873
Henry300357
Hale291584
Cherokee288353
Fayette277973
Washington245148
Crenshaw237069
Cleburne231150
Clay226765
Macon218658
Lamar193342
Conecuh181346
Lowndes170758
Coosa168033
Wilcox159736
Bullock148842
Perry136336
Sumter124336
Greene120642
Choctaw73326
Out of AL00
Unassigned00
Tupelo
Clear
61° wxIcon
Hi: 83° Lo: 55°
Feels Like: 61°
Columbus
Clear
57° wxIcon
Hi: 82° Lo: 53°
Feels Like: 57°
Oxford
Clear
57° wxIcon
Hi: 80° Lo: 52°
Feels Like: 57°
Starkville
Clear
59° wxIcon
Hi: 82° Lo: 53°
Feels Like: 59°
While some cool mornings are again in store for the weekend, afternoons start to warm up a bit, so plan on dressing in layers if you're heading to the MSU or Bama games, because you'll need to utilize them in different ways.
WTVA Radar
WTVA Temperatures
WTVA Severe Weather