Viral News

Hadassah research head raises questions about mRNA vaccine safety

Prof. Yossi Karko explains Israel’s vaccine candidate, questions efficacy of Russia’s Sputnik V

Hadassah-University Medical Center's Prof. Yossi Karko (left) and Hannah Drori, chief of the hospital’s clinical research center, administer Brilife vaccine to a volunteer (photo credit: HADASSAH)

Hadassah-University Medical Center’s Prof. Yossi Karko (left) and Hannah Drori, chief of the hospital’s clinical research center, administer Brilife vaccine to a volunteer

(photo credit: HADASSAH)

The director of the clinical research unit at Hadassah, Prof. Yossi Karko, has warned that there are limitations to the data published by Moderna and Pfizer about their coronavirus vaccine candidates. 

Both companies have applied for Emergency Use Authorization (EUA) for their coronavirus vaccine candidates from the Food and Drug Administration. However, Karko, who has been overseeing the clinical trial of Israel’s vaccine at his hospital, said that “while they seem to be very efficient vaccines, we have to remember that this data has shortcomings.”

First, he told The Jerusalem Post, the data only tracks volunteers for one month following vaccination – “and it really protects subjects quite well now.” However, questions remain about what happens next month and the month after.

“We do expect that the vaccine will protect us for a longer period of time, but this data is not available,” he said.

Second, Karko noted that the safety data is “very short” – spanning the period of about two months from inoculation. 

“The FDA has a mechanism of approving drugs and vaccines for emergency cases. What this means is that the FDA has initial safety data. But if this was a usual situation, the researchers would have followed the volunteers for at least two years before the vaccine was approved.

“We need to know these reservations,” Karko said. “These things are new. There are concerns and we have to be very careful.”

He added that he is not saying that the vaccines are “not excellent or terrific, but we should be aware of the limitations of the data.”

Pfizer and Moderna’s vaccine candidates are both messenger RNA (mRNA) vaccines. If approved, these will be the first-ever vaccines of this type brought to market for human patients.

These vaccines use a sequence of genetic RNA material produced in a lab that, when injected into people, enters their cells and sparks the production of the viral components that subsequently train your immune system to fight the virus.

Michal Linial, a professor of biological chemistry at the Hebrew University of Jerusalem, told the Post that she believes there is no cause for concern.

Linial explained that “mRNA is a very fragile molecule, meaning it can be destroyed very easily… If you put mRNA on the table, for example, in a minute there will not be any mRNA leftover. This is as opposed to DNA, which is as stable as you get.”

She said that this fragility is true of the mRNA of any living thing, whether it belongs to a plant, bacteria, virus or human.

As such, she said the worry should not be that the mRNA won’t get into the cells and instead will stay outside, floating in the body and causing some kind of reaction. Rather the concern should be that if it doesn’t enter the cells, it will disintegrate and therefore be ineffective.

She said that while Moderna and Pfizer are based on new vaccine technologies, they are asking our bodies to do something they do every day: protein synthesis, the process where cells make proteins.

In contrast to the mRNA vaccines, Karko said that Israel’s Brilife, which was designed by the Israel Institute for Biological Research, is a vector-based vaccine. The vaccine took the virus vesicular stomatitis virus (VSV) and genetically engineered it so that it would express on its envelope the spike protein of the novel coronavirus. 

Once injected it does not cause a disease by itself; VSV does not infect human beings. On the other hand, the human being recognizes the spike protein that is expressed on the envelope and the body begins to develop an immunological response.

“It’s like getting a virus like coronavirus without getting the disease,” he said. “Then, if you happen to be exposed to the real coronavirus, the immunological  response that was triggered by the vaccine will prevent infection.”

Phase I of the IIBR study completed last week and Phase II is meant to launch in the next two weeks.

“Up to now, there are no safety concerns,” Karko said. “We are very happy with the results.”

The Phase I study included 80 volunteers – 40 inoculated at Hadassah and 40 at Sheba Medical Center. 

The Phase II trial will include 960 patients and take place at nine medical centers across the country: Hadassah, Sheba, Barzilai Medical Center, HaEmek Medical Center, Tel Aviv Sourasky Medical Center, Samson Assuta Ashdod University Hospital, Rambam Medical Center, Shamir Medical Center and Meir Hospital.

The Phase I study included healthy volunteers between the ages of 18 and 55. The Phase II study will include volunteers between the ages of 18 and 85, including those with some chronic diseases. The medical centers are actively recruiting for this study now.

On Monday, IIBR head Prof. Shmuel Shapira charged that the country’s vaccine candidate could have been further along but it was delayed due to “over-regulation” by the Health Ministry. Karko said that, “Israel’s regulatory bodies were never asked to evaluate a vaccine” and “under the circumstances, they stood up to the challenge.”

When asked why IIBR would not aim for FDA or even European Medicines Agency approval, he said that “IIBR does not have presumptions to produce a vaccine that is going to be commercialized. The objective is to produce an efficient and safe vaccine to serve the citizens of Israel.”

He said that while there is excitement that Pfizer or Moderna vaccines could arrive in the country by the end of December, he does not believe Israel will receive enough doses for mass vaccination before the end of next year, making it even more necessary for the country to develop its own vaccine.

Moreover, he added that he believes coronavirus will mutate and be with the world for more than a year. As such, “it seems to me we will need to vaccinate more than once. Under these circumstances, having our own ability to produce a vaccine is important.”

And what about Russia’s Sputnik V vaccine, which Hadassah is vying to manufacture in Israel?

“It is a well-developed vaccine,” he said. But he admitted that the clinical process of evaluating the efficacy of the vaccine could be “deficient.”

“Until I see a publication with scientific data that has undergone peer review I cannot really comment,” he added. 

Read More

Show More

Related Articles

Leave a Reply

Your email address will not be published. Required fields are marked *

Back to top button

Adblock Detected

Please consider supporting us by disabling your ad blocker