Experts skeptical after researchers report positive vaccine results

CNN's Elizabeth Cohen responds to Dr. Deborah Birx's comments about a new hydroxychloroquine study during a White House press briefing.

Posted: May 23, 2020 5:01 PM
Updated: May 23, 2020 5:01 PM

Researchers in China reported results from one of the first Covid-19 vaccine trials Friday, but experts who spoke to CNN were skeptical of their findings and called the data lukewarm.

In a study published in the medical journal The Lancet, researchers said their vaccine was well-tolerated and generated an immune response against the novel coronavirus.

The vaccine, developed by CanSino Biological Inc. and the Beijing Institute of Biotechnology, was tested in 108 healthy adults ages 18 to 60 in Wuhan, China, none of whom were infected with the virus.

All the participants received injections at low, middle or high doses, and no "serious" side effects were reported, according to Wei Chin of the Beijing Institute of Biotechnology and colleagues, who ran the trial.

Weak responses

Still, almost half of vaccine recipients reported fever, with 44% reporting fatigue and 39% reporting a headache. Overall, 9% of patients reported side effects that were severe enough to have potentially "prevented activity."

These side effects are "not a good safety sign," said Dr. Paul Offit, director of the Vaccine Education Center at Children's Hospital of Philadelphia.

In addition, he said, the vaccine did not elicit a strong immune response.

According to the study, about half of recipients in the low- and middle-dose groups developed neutralizing antibodies, which can bind to the coronavirus and neutralize its effects.

About three-quarters of people in the high-dose group developed antibodies, but researchers also noted some severe side effects in that group. They said they won't be giving such a high dose in future studies.

Offit said the immunogenicity data was "not impressive," especially since all of the doses -- even the "low" dose -- were actually very high, he said. Combined with the side effects, he recommended that the CanSino researchers give up on their efforts.

"I think they should stop," said Offit, who previously developed a successful rotavirus vaccine. "I have to believe there are other candidates out there that are going to do better than this."

Dr. Peter Hotez, dean of the National School of Tropical Medicine at the Baylor College of Medicine, also wasn't thrilled with the findings. "I'm not impressed with this," he said.

Still, he said researchers should keep studying the vaccine, either to use on its own or alongside another vaccine in what's called a prime-boost approach.

"The good news is, (the vaccine) is producing neutralizing antibodies, which scientists think is important for protective immunity against Covid-19," said Hotez, who is also working on a vaccine against Covid-19. "What is less certain is whether the levels of neutralizing antibody are high enough to confer complete protection, or whether this will be partially protective."

Clinical trial in China will study 500 volunteers

The vaccine from the Beijing researchers uses what's called an adenovirus vector. Adenoviruses can cause the common cold, but in this case, they're weakened and modified to deliver genetic material that codes for a protein from the novel coronavirus.

The body then produces that protein and, ideally, develops an immune response against it. In the new study, the vaccine produced a complex immune response, prompting most volunteers to produce both T-cells that should attack the coronavirus and antibodies as well.

This particular vaccine used an adenovirus strain called adenovirus 5. People who had some immunity to that strain did not seem to respond as well to the vaccine, the researchers said.

Chen called the results encouraging but said more research is needed.

"The trial demonstrates that a single dose of the new adenovirus type 5 vectored COVID-19 (Ad5-nCoV) vaccine produces virus-specific antibodies and T cells in 14 days, making it a potential candidate for further investigation," he said.

"However, these results should be interpreted cautiously. The challenges in the development of a COVID-19 vaccine are unprecedented, and the ability to trigger these immune responses does not necessarily indicate that the vaccine will protect humans from COVID-19."

He said the result "shows a promising vision for the development of COVID-19 vaccines, but we are still a long way from this vaccine being available to all."

According to The Lancet's press release, researchers have initiated a randomized, double-blind, placebo-controlled trial in Wuhan, China to further test the vaccine -- the gold standard for clinical research.

The study will look at 500 healthy adults, according to the Lancet, with half of the volunteers given the middle dose, 125 given the low dose, and 125 given a placebo. The research will include participants over 60 years old.

The vaccine is just one of many in development. There are currently 10 in human trials around the world, with four in the US, five in China -- including CanSino -- and one in the UK. More than 100 vaccines are also in preclinical trials, according to the World Health Organization.

Indiana Coronavirus Cases

Data is updated nightly.

Cases: 768624

Reported Deaths: 13993
CountyCasesDeaths
Marion1055891807
Lake569801031
Allen43032699
St. Joseph37344568
Hamilton37335426
Elkhart29783470
Tippecanoe23503230
Vanderburgh23240405
Porter19580327
Johnson18843392
Hendricks18089323
Madison13575347
Clark13552198
Vigo12869256
LaPorte12578225
Monroe12575178
Delaware11155198
Howard10693237
Kosciusko9792124
Hancock8761150
Bartholomew8274157
Warrick8084157
Floyd8043182
Grant7378181
Wayne7239201
Boone7211105
Morgan6924143
Marshall6345117
Dubois6283118
Cass6096112
Dearborn602178
Noble600890
Henry5958111
Jackson517277
Shelby511598
Lawrence4928127
Gibson463696
Montgomery459292
DeKalb456785
Clinton456055
Harrison454077
Huntington417882
Whitley416745
Steuben411260
Miami406073
Jasper401655
Knox388691
Putnam385762
Wabash370384
Adams353856
Ripley351971
Jefferson343487
White340154
Daviess3089100
Wells304081
Greene295185
Decatur292693
Fayette286564
Posey282635
Scott281058
LaGrange277772
Clay274949
Washington254637
Randolph247783
Jennings239749
Spencer238731
Fountain235850
Starke229959
Owen222959
Sullivan221643
Fulton208945
Jay203032
Carroll197722
Orange191756
Perry189939
Vermillion181144
Rush177627
Tipton173347
Franklin172535
Parke155916
Pike142534
Blackford138032
Pulaski123748
Newton123336
Benton109715
Brown106243
Crawford105816
Martin92515
Warren87915
Switzerland8378
Union73610
Ohio58411
Unassigned0429

Ohio Coronavirus Cases

Data is updated nightly.

Cases: 1125420

Reported Deaths: 20490
CountyCasesDeaths
Franklin1305631493
Cuyahoga1173952263
Hamilton825481261
Montgomery536581062
Summit489381014
Lucas43799834
Butler40064614
Stark33876939
Lorain26072510
Warren24959312
Mahoning22738613
Lake21482396
Clermont20425261
Delaware19169138
Licking16879227
Trumbull16829492
Fairfield16825207
Medina15880276
Greene15565254
Clark14366308
Portage13450218
Wood13358201
Allen12064245
Richland11748213
Miami11047228
Wayne9275228
Columbiana9216236
Muskingum9144137
Pickaway8755123
Tuscarawas8724255
Marion8716140
Erie8146166
Ashtabula7280179
Hancock7050135
Ross7031165
Geauga6975153
Scioto6726108
Belmont6224179
Lawrence5964104
Union591649
Jefferson5729162
Huron5644122
Sandusky5498130
Darke5448131
Seneca5380128
Washington5373111
Athens527260
Auglaize507787
Mercer491785
Shelby484397
Knox4621113
Madison448066
Ashland446198
Defiance439499
Fulton436875
Putnam4358104
Crawford4120111
Brown410462
Preble3956107
Logan392279
Clinton391466
Ottawa376481
Highland366668
Williams357378
Champaign349860
Guernsey331554
Jackson321954
Perry299050
Morrow294943
Fayette289350
Hardin279665
Henry277467
Coshocton273061
Holmes2726102
Van Wert252365
Gallia251150
Adams250958
Pike244837
Wyandot235557
Hocking222963
Carroll201449
Paulding180142
Meigs151540
Monroe137945
Noble137939
Harrison115438
Morgan111724
Vinton87517
Unassigned04
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