Search Results for "vaccine"

Jun 27 2022

Flu Vaccines Associated With Reduced Alzheimer’s Risk

Published by under Neuroscience

A recent large population-based study shows a significant reduction in the risk of developing Alzheimer’s disease (AD) in older adults who received one or more flu vaccines. This follows previous studies showing a similar protective effect for other adult vaccines, and raises interesting questions regarding possible mechanisms.

AD is a degenerative neurological disease which is the most common cause of dementia, which is a syndrome of chronic global cognitive impairment. The prevalence of AD is about 6.5 million people in the US. The risk of developing AD increases with age, with 10.7% of those 65 and older being affected. AD is more than just having dementia, it is a specific disease that can only be confirmed at this time by looking at the brain. There are pathological changes including plaques and tangles. Imaging can also reveal diffuse cortical atrophy (shrinkage of the brain). Electroencephalogram typically shows slowing, indicating reduced cortical activity. There are many markers of AD that can be identified in the blood or spinal fluid, but none are good enough to be used in routine clinical evaluation.

The causes of AD are complex and not yet fully understood. In brief, a lot of stuff happens on the way towards brain cells dying but it’s hard to known which stuff is driving the process and which are a result of the process. It therefore has been difficult to device treatments to slow or prevent progression. For my entire career as a neurologist it seemed as if we were getting close to a significant clinical breakthrough, but we’re still waiting. Tremendous progress has been made, but nothing that amounts to a disease-modifying treatment.

Prevention before the disease becomes clinically apparent would be ideal. We know that controlling blood pressure and other markers of cardiovascular health are extremely important in reducing the risk of AD. We also know that physical exercise is important, as well as keeping mentally active. Sometimes, however, it is difficult to separate preventive measures that actually delay or slow the onset of AD vs those that mask the onset through creating a higher baseline of cognitive function. Regardless, all of the above are good lifestyle choices.

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Jul 20 2021

We’re Losing the Vaccine Race

In February on SBM I wrote about the Race Against Vaccine Hesitancy. At that point in time the pandemic was receding in the US in the face of a rapid vaccination program, but also the first new variants of SARS-CoV-2 were starting to appear. Essentially I argued that we were in a race between achieving herd immunity and the spread of new variants that might be more contagious or even vaccine resistant. Experts believed that we would know the answer by Summer.

Well, Summer is here, and the answer is in. We lost the race. Vaccine hesitancy won.

This doesn’t mean that the vaccination program has not been massively helpful. It has. As of now 48.6% of the US population is fully vaccinated, with 56.1% having received at least one dose. This includes children under 12, however, who are not currently eligible for any vaccine. A total of 68.3% of adults have been vaccinated, close to the 70% goal set by the Biden administration. From a logistical perspective, this is a success. The program peaked at over 3 million doses given per day. The program meant that the limiting factor was not the availability of vaccines or the ability to distribute and administer them. The limiting factor is people willing to get vaccinated.

While we may have come close, we did not achieve sufficient herd immunity. Part of the problem is that the vaccinated are not evenly distributed throughout the population. Vaccine uptake is patchy, which means there are clusters of unvaccinated people where the virus is free to spread. Arkansas, for example, is only at 35% fully vaccinated.

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May 07 2021

COVID Vaccines Are Safe and Effective

We are at a critical point in this pandemic. Worldwide the pandemic is actually more active now than ever. There have been over 156 million cases, and the world is seeing almost 800k new cases a day. The recent peak is mainly due to India, but infections continue throughout the world. The high number of cases also increases the risk of new variants emerging. India also shows us how quickly medical resources can be overwhelmed with catastrophic results. They ran out of oxygen – which is critical to keeping severe COVID patients alive.

Yet, with each wave there was the prevailing sense that this was the worst we’ll get, and now we are rounding the corner. So far, this has been wrong every time. Of course this pandemic must end eventually, the question has always been how much death, morbidity, and economic damage would it cause in the meantime. The primary reason for the next worse wave of the pandemic has largely been that people eased off on pandemic protocols. They stopped wearing masks and social distancing and started gathering in large groups. And each time the virus made us pay for it.

But now, despite being in the middle of the biggest wave so far, the situation is changing, because now we have multiple safe and effective vaccines. In the US there are two mRNA vaccines, from Moderna and Pfizer-BioNTech, in addition to the J&J vaccine. Other than a minor hiccup with extremely rare blood clots, these vaccines have a great safety profile. In states with high vaccine uptake the virus is getting under control, and restrictions are starting to be safely lifted. Life is partly getting back to normal – thanks entirely to the vaccines.

But we are facing two problem – entirely of our own making. The first is that we are in a race against time. We have to vaccinate enough of the world to achieve herd immunity before new variants emerge that are resistant to the vaccines. Also, we don’t know how long immunity from the vaccines last, but it may be something around a year. So when we get to a year out from the first vaccines given, we need to do it all over again with booster shots. Perhaps even more importantly, we are running up against vaccine hesitancy, which may ultimately prevent us from getting to herd immunity. That would be a tragedy.

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Apr 15 2021

Paul Thacker Trolling Skeptics on Vaccines

Published by under Skepticism

As the COVID vaccine rollout continues at a feverish pace, the occurrence of rare but serious blood clots associated with two adenovirus vaccines, AstraZeneca and Johnson & Johnson, is an important story, and should be covered with care and thoughtfulness. I have followed this story on Science Based Medicine here, here, and here. There is a lot of nuance to this issue, and it presents a clear dilemma. The ultimate goal is to optimally balance risk vs benefit while we are in the middle of a surging pandemic and while information is preliminary. This means we don’t panic, we consider all options, and we investigate thoroughly and transparently. There is a real debate to be had about how best to react to these rare cases, and as a  science communicator I have tried to present the issues as reasonably as possible.

But we no longer live in an age where most people get most of their science news from edited science journalists. Most get their news online, from a range of sources, some good, some bad, some acting in bad faith or filtered through an intense ideological filter, and many just trolling. There are even “pseudojournalists” out there, reporting outside any kind of serious review. One such pseudojournalist is Paul Thacker, who recently decided he had to criticize the reporting of “skeptics” on the COVID vaccine blood clotting issue.

For background, Thacker was fired from the journal Environmental Science & Technology for showing an anti-industry bias. Bias is a bad thing in journalism, the core principle of which is objectivity. I have no idea if Thacker honestly believes what he writes or if he can’t resist trolling, but it doesn’t really matter. He has espoused anti-GMO views to the point of harassing GMO scientists, leading Keith Kloor to call him a “sadistic troll”. Thacker has also promoted 5g conspiracy theories.

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Jan 19 2021

Be Skeptical of Video Showing Vaccine “Side Effect

This was inevitable. We are in the midst of a massive rollout of two new vaccines for COVID-19. Anxiety and fatigue levels from the pandemic are already running high, and there is a pre-existing anti-vaccine movement who is sure to exploit this. But perhaps most significantly, we are now living in a post-social media world. Information, even medical or scientific information, may get to the public unfiltered, ripe to be misinterpreted by people who do not understand the relevant science. Such is the case with a “viral” video showing a woman who claims her symptoms are a side effect of the Moderna vaccine (short answer – they almost certainly are not).

Messaging is critical to the success of public health measures. Normally information about possible side effects from a drug or vaccine would be filtered through medical experts. When millions of people are involved there is going to be a lot of noise. Coincidence alone would result in many negative outcomes occurring by chance alone shortly after getting a vaccine. Epidemiologists need to look for patterns in the data that indicate there is likely to be an actual causal relationship to the vaccine. It helps if there is also a plausible mechanism. This system has captured vaccine side effects in the past, so you cannot reasonably argue that the system is rigged not to find such associations. The swine flu vaccine in the 1970s caused cases of Guillaine Barre Syndrome. A specific flu vaccine (Pandemrix – no longer on the market) likely caused cases of narcolepsy in 2009. So if any of the current COVID vaccines have a similar side effect, we will catch it.

Reporting scary anecdotes that have not been scientifically evaluated to the public is not a good idea. This is likely to misinform rather than inform, and will have a death toll attached to it. But with social media there is no way to stop this from happening, so we just have to do damage control when it does.

As a side note, I have to point out that I usually refrain from commenting on a specific individual’s medical condition in public. This is to respect the privacy of those individuals, and also because if I have not personally examined them and taken their history, commenting is inappropriate. But medical science communicators can comment about topics relevant to a public case or issue. I can speak generally about the relevant topics. There is also an exception when a private person puts their own medical history into the public domain, especially if they also use that history to make recommendations to the public, and doubly so if those recommendations are false and harmful. They have surrendered any expectation of privacy and they have made their own personal history relevant to the discussion about a public health issue. That is the case here.

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Dec 17 2020

It Took Two Days to Develop Moderna’s Vaccine

As the first crop of SARS-CoV-2 vaccines are being rolled out, we can start to see the light at the end of this pandemic tunnel. Still, in the US alone there will probably be another 200,000 deaths before we reach herd immunity. Further, as fast as this vaccine development and deployment was, it’s not clear how much faster it will bring an end to the pandemic. We will likely be 18 months into the pandemic before we have significant vaccine uptake, and that may not be far off from how long the pandemic was going to last in the first place. There is no doubt is will save lives and hasten the end, but still – only after we lost about half a million people to the virus.

The question for the future, therefore, is this – is it possible to develop a vaccine even more quickly? What if we could get a vaccine out, soup to nuts, in just a couple of months. We could have ended the pandemic before it really began. The first shots could have been going out in March, protecting front-line workers and the most vulnerable. This would have dramatically slowed the spread while the general population got the vaccine. By now we would be at the tail end of distribution, not the beginning. The COVID pandemic which disrupted the world would have been more like a mild flu season.

Is this feasible? The answer is a definite yes. In fact, as is now being widely reported, it took Moderna just two days to develop their vaccine. They had the vaccine – in January. This is because Moderna has spent the last 10 years developing the mRNA vaccine technology that they used in their COVID vaccine. This, in fact, is the huge advantage of mRNA vaccines, and partly why this technology was being developed. It worked as designed. As soon as the Chinese government released the genetic sequence of the SARS-CoV-2 virus, that was all Moderna needed. They identified the sequence for the spike protein, plugged that into their vaccine platform, and voila – an mRNA vaccine against the SARS-CoV-2 virus. Actually, I’m sure it was more complex than that, but whatever the technical details, it took only two days. And the core idea here is valid – they really only needed the genetic sequence of the organism, which itself now can be done very quickly.

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Dec 14 2020

mRNA Vaccines

This week should see the first people in the US to actually receive an approved (at least EUA) vaccine to prevent SARS-CoV-2. There are three vaccines currently ready to go in the West, the Pfizer vaccine which received it’s EUA in the US on Friday and was already approved in the UK, Moderna which should get approval this week, and the Astra Zeneca vaccine which should not be too far behind. The (arguably) biggest challenge has been met – a massive scientific effort to develop vaccines in record time. This has been a collaboration between government and industry, and shows what we can accomplish with sufficient motivation (which translates into both money and easing red tape).

Now we have three further challenges in front of us. The companies need to mass produce their vaccines. This is happening with about 100 million doses ready to ship. We should have another 2 billion Pfizer doses by the end of 2021, and 1.5 billion Moderna doses. We also need to distribute the doses. This is happening through collaboration among FedEx, UPS, and the military who will get the doses to hospitals and physicians, who can then administer and track the doses. So far, so good.

The final hurdle, however, may prove the stickiest – we need people to accept the vaccine. In a December 9th survey by the AP-NORC, only 47% of Americans said they would get the vaccine, with 26% saying they would not, and 27% saying they are not sure. These and similar results have caused some to comment that the disinformation virus may prove deadlier than the COVID virus. We have a vaccine that can protect people from a deadly pandemic – this is a no-brainer. Resistance is partly due to a dedicated anti-vaccine movement that appears immune only to logic and evidence. We can only marginalize them. But these numbers go beyond the hard-core anti-vaxxers. People also fear what they don’t know, and these are the first mRNA vaccines to hit the market. So let’s review what these are, and the safety data.

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Nov 24 2020

We Have Several Vaccines for COVID – Now What?

Two weeks ago Pfizer and German company BioNTech announced preliminary analysis of their phase 3 trial of an mRNA-based vaccine for SARS-CoV-2 showing it is 90% effective (later updated to 95%). One week ago Moderna announced that they too had promising results from their phase 3 trial, also an mRNA vaccine showing 95% efficacy. This week AstraZeneca announced they have developed a COVID vaccine as well (in partnership with Oxford University).

I have not discussed the AstraZeneca vaccine before, so here are the basic facts: “It uses a replication-deficient chimpanzee viral vector based on a weakened version of a common cold virus (adenovirus) that causes infections in chimpanzees and contains the genetic material of the SARS-CoV-2 virus spike protein.” In the study, overall there was a 70% efficacy in reducing symptomatic cases of COVID-19. However, in a subgroup analysis, those receiving a half dose followed by a full dose (instead of two full doses) had 90% efficacy, which is closer to the two mRNA vaccines. It is too early to say if this difference is real, and it does not make biological sense, so the company plans to expand the number of subjects getting this dosing regimen to see if the higher efficacy holds up. One advantage to this vaccine is that it can be stored in a regular refrigerator for up to 6 months, while the mRNA vaccines have to be frozen for transport (the Pfizer vaccine at -70 degrees C, the Moderna vaccine at -20).

All three vaccines have a good safety profile so far, but it always takes time to monitor for side effects so this is an ongoing assessment. Pfizer and Moderna say they can  produce over a billion doses by the end of 2021, and AstraZeneca says they can produce 3 billion doses. That is enough for about a third of the world’s population. Of course, there are many other vaccines being developed around the world so these won’t be the only three.

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Sep 11 2020

COVID Vaccine News

By now most people have heard that AstraZeneca, a UK pharmaceutical, working with Oxford University, are one of the major companies developing a vaccine for SARS-CoV-2, and also that they have had to pause their Phase 3 clinical trial because a subject came down with an inflammatory disorder. Let’s put this into some important context.

The basic facts are that the AstraZeneca vaccine did very well in Phase 1 and 2 preliminary trials. These are smaller trials mostly about safety, with the Phase 2 trial including some preliminary (usually open label) efficacy data. These trials are basically used to determine if it is safe and worth it to proceed to a huge Phase 3 trial. The Phase 3 trial includes 30,000 subjects. When you increase the number of subjects by orders of magnitude then you are likely to pick up increasingly rare side effects. That is one of the main points of this staged approach to research. Then, of course, a drug or vaccine might be marketed to millions of people, and still more rare side effects will crop up. There is simply no way to avoid this – it’s math. That is why so-called Phase 4 trials follow reported side effects after market.

But also, when you are studying 30,000 subjects all the things that normally happen to people will happen at the background frequency. Some of them will get sick during the trial by chance alone, having nothing to do with the study drug or vaccine. So every potential adverse effect is tracked, determined if it is biologically likely that it is related to the experimental treatment, and then statistically analyzed to see if it is above the background rate.

In this case one subject developed transverse myelitis, which is inflammation in one segment of the spinal cord. This will cause weakness and numbness at that level and below, therefore usually affecting the legs. The background incidence of transverse myelitis is about 1.3-4.6 cases per million people per year (this does not include people known to have an autoimmune disease like MS that causes transverse myelitis). If we take 4 cases per million per year, that translates to 0.033 cases per 33,000 subjects over three months. That is the probability that one of the subjects in that trial would have randomly developed transverse myelitis. That may seem really unlikely, but actually you have to consider the probability of a subject developing any disease, not just transverse myelitis. When you add it all up it’s actually pretty likely that one or several people in the trial would randomly develop a disease not related to the vaccine. In fact, this is the second person in this particular trial to develop a serious potential adverse event resulting in a pause of the trial.

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May 04 2020

COVID-19 Immunity and Vaccines

We appear to be at the beginning of the end of the first wave of COVID-19 (at least in the US – other countries are at different places). We are at the point where states are starting to relax the physical distancing requirements, and there is discussion about how to transition to the next phase. That next phase might include disease tracking, targeted isolation, and “immunity passports.” But planning this next phase is complicated by the fact that we still do not fully understand this virus. We don’t know if there will be a second wave (or more), if it is seasonal, and if you can catch it twice. How we handle this next phase will likely determine if there is a second wave.

But what comes after that? When can we transition to the final phase – return to normal, even if it is a new normal? These next transitions will depend largely on the natural immunity that results from infection, and how long it will take to create a vaccine and how effective that vaccine is. Here is what we know and don’t know so far.

The big question for the next phase is – how much immunity results from natural infection? This is a more complicated question than it may first seem. But the short answer is, we don’t know.

The adaptive part of the immune system will remember infections, B-cells that create specific antibodies targeting the infecting organism will develop throughout an infection, and some of those B-cells are memory B-cells – they will hang around for a long time, ready to produce specific antibodies the next time the same organism is encountered. But there are important variables to how effective this adaptive immune strategy is. the virus or infecting organism itself is the main variable. What parts of itself does it expose to the immune system? Perhaps the critical functional proteins are hidden deep within folds that antibodies cannot get to. Another variable is how quickly does it mutate? If the parts that antibodies can target change quickly, then immunity does not last. Some organisms also evolve specific strategies to evade or compromise the immune system.

Another variable is the severity of the infection itself. The more severe and long lasting the infection, the greater the stimulation to the immune system and the greater the adaptive response.

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