StemCell Therapy

Creating a vaccine that would be injected into the arms of millions of people is a usually a years-long endeavor. Not only is the process slowed by trial and error and first-time failures, it's also traditionally restricted by rigorous clinical trials that in their final stages can give public health authorities a reasonable idea of whether a vaccine is safe and effective.

But not even a full year after the first infection from the novel coronavirus in China was documented, the White House is now saying a vaccine could be fast-trackedas soon as early November.

A safe, effective shot produced so rapidly would be unprecedented. It could also save tens of millions of Americans from falling ill with Covid-19 and prevent countless deaths. And the U.S. could desperately use a shot in the arm in its losing fight against the outbreak: Nearly 6.5 million Americans have been diagnosed with the virus -- with some severely sickened-- and nearly 200,000 have been killed.

But what if a hastily rolled out vaccine that skips the final stages of study turns out to have unforeseen problems -- either with safety or efficacy? What happens, for example, if millions of vials are distributed of a prematurely OK'd vaccine and then it turns out to be inferior to a better one that completes all trials months later? What if fading antibodies mean a vaccine's protection wears off after only a short time -- a possibility that can't be known with trials only carried out over several months? Would your own physician even recommend a fast-tracked vaccine if it lacked key data that would be typically expected for review?

To sort through these questions, we asked Dr. Otto O. Yang, a veteraninfectious disease expert and medical doctor at the David Geffen School of Medicine at UCLA. Yang specializes in clinical infectious diseases, and his laboratory focuses on T-cell immunology in HIV infection, as it relates to developing immune therapies and vaccines for HIV and other diseases and infections.

While it would be impossible to predict which of the dozens of vaccine candidates might be most likely to see early approval, said Yang, the two leading candidates could be themRNA nanoparticle vaccine byModerna (MRNA) - Get Reportand therecombinant adenovirus one byOxford University and AstraZeneca (AZN) - Get Report.

"From the limited amount of data Ive seen" that's publicly available, said Yang, "it looks like both vaccine candidates generate the right types of antibodies that we would expect to be effective at preventing infection. And, they both generate T-cell responses, which could be effective in more than one way."

But there are many other factors at play in creating a Covid shot -- and there could be unexpected consequences of speeding through vaccine approvals or just running with the first one that looks acceptable.

Yang was reached by phone this week by TheStreetto discuss these vaccine projects, the possibility for a fast-track OK and potential pitfalls. The following is an edited version of the interview.

TheStreet: Specifically, looking at the vaccine project by Oxford University and AstraZeneca, Ive heard some concern that it might prevent the development of full-blown disease in patients, but might not prevent the spread of the virus from one person to another. What are your thoughts?

Yang: Its a theoretical possibility. So, if a vaccine doesnt fully protect somebody from getting infected, its possible they could get a milder infection. Even with the flu vaccine that we get annually, in some cases it appears to make infection milder, even if it doesnt protect you from getting infected. But I think its most likely that even if somebody did get infected, the immune responses that would be put in place by the vaccine would probably reduce symptoms and reduce severity. If so, it would most likely reduce the degree to which somebody is contagious. Its a theoretical concern, but not something that I would be that worried about.

TheStreet: In a general sense, weve seen reports about, and youve researched, the potential for fading of antibodies. Is there a concern that there could be a vaccine that is safe and it seems to work and then, say six months down the road, somebody gets infected, though they were vaccinated?

Yang: Its definitely a possible scenario. Potentially dropping antibodies might mean that immunity will wane, but its not entirely clear that thats true. The fact is that immunology is kind of a black box and we dont know for sure that antibodies are the whole story for protecting somebody from infection. The data are worrisome that protection will be short-lived for natural infection. And there recently have been increasing news reports of people getting reinfected. That does raise concerns for the longevity of protection from a vaccine, and, of course, short-term vaccine trials are not going to be able to tell us about longevity.

That does raise concerns for the longevity of protection from a vaccine, and, of course, short-term vaccine trials are not going to be able to tell us about longevity.

But one of the big unknowns is whether the vaccine could actually do a better job at making antibodies or T-cell responses than natural infection itself. The study that we did on dropping antibodies was on people who were naturally infected and had fairly mild disease. It is clear that people with more severe infection have fairly high antibody levels, so a vaccine could look more like that like a person who has a more severe infection and fairly high levels of antibodies.

The other thing is, we dont know if the virus actually has mechanisms to interfere with immune response. Many viruses have evolved to have ways to blunt the immune response to enhance their survival. From an evolutionary standpoint, if the immune system is trying to do something to reduce the virus, then the virus can evolve to counter that. If thats the case with this virus if immune response is short-lived because the virus is actively doing something to the immune system to cause that a vaccine could theoretically do better, because the vaccine is not the whole live virus. It might not have that negative impact on the immune system. Well have to just wait and see.

TheStreet: Do you think fast-tracking a vaccine by, say, skipping or shortening the final clinical trials, would be warranted? Hong Kong, Taiwan, New Zealand, China and many other countries have proven that the spread of Covid-19 can be mostly controlled with public health measures.

Yang: So, theres the ideal, theoretical answer, and theres the practical answer. Unfortunately, we are much less like Taiwan or New Zealand, than we are like Brazil. From the standpoint that this country has been unable to implement effective public health measures, for whatever reason, that makes the urgency for a vaccine higher. Ideally, we would be able to get the pandemic under control to an acceptable level and take our time with the vaccine. But theres added urgency, because, for various reasons, were unable to do that theres not enough public buy-in, theres not enough political leadership. Whatever the reasons, were unable to contain it, and the pandemic is just burning on and lives are being lost, so that adds greater urgency for a vaccine

TheStreet: Would you take a fast-tracked vaccine would you recommend it to friends or family?

Yang: It would really depend on what data were available ... safety data being No. 1., and, of course efficacy. I would say that I would certainly be cautious and hesitant, because I feel that the Food and Drug Administration has lost a lot of its credibility, because of its bowing to political pressures. Its already made major fumbles during this pandemic. So I would go with what experts say, and if there is not enough available data to make me feel comfortable to recommend it, then I would say dont take it. Because, as you pointed out, with the right measures, you can prevent spread and you can(potentially)protect yourself from getting infected. So, until its clear that a vaccine is safe and effective, we can each protect ourselves.

TheStreet:That brings up another question. Lets say a vaccine is fast-tracked and millions of doses are produced, and, then, say, several months later, a problem is discovered with the vaccine. At the same, lets say, another vaccine that finishes all its trials comes along and it looks great. Would that pose a logistical problem for distributing the latter, better vaccine could it cause a vaccine production traffic jam?

Yang: Yes, in more ways than one. Lets, for argument, say one vaccine is 50% effective and the other is 75% effective, what do you do? What do you do with all these 50% effective vaccine vials you have sitting around? Is there going to be motivation to get them out and get them used? It raises all sorts of questions about what would happen. What would be the threshold for saying you just throw out the first vaccine which would be at a huge cost? Another point to raise is potentially the first vaccine could interfere with the second. The first vaccine might steer your immune responses in ways that are less effective than the second would have. To some extent, the immune system tends to be trained in a certain way, and once its trained, its hard to get it to change. Theoretically, there could be interference.

Potentially the first vaccine could interfere with the second.

Theres a concept in immunology called original antigenic sin. The concept is that the immune system tends to want to react to something the same way every time, so if you challenge it with something that looks very similar, but is not exactly the same, it will still stick to the original way that it responded. That is the explanation for Dengue fever. Dengue fever is a disease where you get very mild illness the first time you are exposed, and if you get exposed again, to a second strain, then you can get hemorrhagic Dengue fever, which is a very severe, life-threatening infection, and that is because the immune system is still stuck on the first strain and unable to adapt to the second strain. So, you can see something like that happening, as well. Its not that straightforward.

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Fast-Tracking Covid Vaccine 'Is Not That Straightforward' - TheStreet

This entry was posted on September 13, 2020 at 2:52 am and is filed under Longevity. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed. |