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: 1000163

Reported Deaths: 16309
CountyCasesDeaths
Marion1347632106
Lake660041156
Allen57441793
Hamilton46100461
St. Joseph44109607
Elkhart35696507
Vanderburgh32087477
Tippecanoe27796257
Johnson24902443
Hendricks23738354
Porter22802362
Madison18614404
Clark18424250
Vigo17347301
Monroe15180197
LaPorte15046250
Delaware14984259
Howard14626287
Kosciusko12217147
Hancock11630175
Bartholomew11505179
Warrick11255189
Floyd11013214
Wayne10897250
Grant9964218
Morgan9404176
Boone8863116
Dubois8227130
Dearborn817093
Henry8139151
Noble7984106
Marshall7838134
Cass7499119
Lawrence7403170
Shelby7138114
Jackson694088
Gibson6533113
Harrison644491
Huntington633999
Knox6273106
DeKalb626397
Montgomery6208109
Miami589797
Putnam575377
Clinton570271
Whitley560455
Steuben554675
Wabash5279101
Jasper524475
Jefferson506996
Ripley495685
Adams476073
Daviess4616113
Scott435869
Greene422096
Wells420987
Clay420260
White415962
Decatur4133101
Fayette404286
Jennings385160
Posey375343
LaGrange353978
Washington353249
Randolph341999
Spencer337342
Fountain332558
Sullivan326752
Starke313369
Owen312070
Fulton306567
Orange291762
Jay280445
Perry264752
Franklin264042
Carroll259132
Rush258832
Vermillion255454
Parke230026
Pike227943
Tipton226659
Blackford190540
Pulaski181855
Crawford158623
Newton156048
Benton150217
Brown144547
Martin137419
Switzerland134211
Warren120516
Union106815
Ohio84112
Unassigned0538

Ohio Coronavirus Cases

Data is updated nightly.

Cases: 1499485

Reported Deaths: 23327
CountyCasesDeaths
Franklin1626291662
Cuyahoga1447662412
Hamilton1044761409
Montgomery731681240
Summit610421094
Lucas55643904
Butler51076707
Stark459431053
Lorain35141568
Warren32476369
Mahoning30315672
Clermont27930321
Lake26669434
Delaware23960162
Licking23547283
Trumbull22550552
Fairfield22179241
Greene22098311
Medina21763305
Clark19630349
Richland18342280
Portage17696247
Wood17244220
Allen15730269
Miami15355296
Muskingum14551174
Columbiana13756263
Wayne13585263
Tuscarawas12479298
Marion11797175
Scioto11388154
Pickaway11286141
Erie10676180
Ross10462196
Lawrence9663137
Hancock9546149
Ashtabula9479197
Belmont9133197
Geauga8829157
Jefferson8481191
Huron8229139
Union810756
Washington8031137
Sandusky7724145
Athens769572
Knox7606138
Darke7553151
Seneca7208144
Ashland6817125
Auglaize667896
Shelby6410111
Brown628582
Crawford6184130
Defiance6087102
Mercer608293
Fulton592996
Highland590099
Madison587576
Clinton576190
Logan574692
Guernsey572467
Preble5660121
Putnam5250108
Williams520184
Perry512561
Champaign505071
Jackson498770
Ottawa479086
Coshocton471582
Morrow451256
Pike430762
Fayette422160
Adams411587
Gallia411265
Hardin411076
Van Wert364078
Henry357871
Holmes3567122
Hocking352578
Wyandot317961
Carroll297059
Paulding275945
Meigs259249
Monroe212953
Noble196546
Morgan190832
Harrison178242
Vinton162624
Unassigned05
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