From a sore arm to anaphylaxis, a wide range of adverse events have been reported after people have received a COVID-19 vaccine. And yet it is unclear how many of these events are actually caused by the vaccine. In the vast majority of cases, reactions are mild and can be explained by the body’s own immune response.
But monitoring systems designed to track adverse events are catching much rarer but more serious events. Now scientists need to work out if they are causally liked to the vaccine, or are just statistical anomalies – and that is not an easy task.News: Why is it so hard to investigate the rare side effects of COVID vaccines?Subscribe to Nature Briefing, an unmissable daily round-up of science news, opinion and analysis free in your inbox every weekday.
Vaccines are one of the most effective tools we have in preventing and reducing the burden of infectious diseases. In the midst of the COVID-19 pandemic, vaccines are once again poised to change the tide in our favor in the fight against a deadly virus. But how exactly do vaccines work? And are they safe? “You can think of your body’s immune system like an orchestra,” says Yale immunobiologist Akiko Iwasaki, PhD. “The different functions of the immune response are like different instruments. And vaccines work like sheet music for the orchestra, telling the immune system what to do and how to do it.” Different viruses require different types of immune responses in order to confer protection, and some of them can be complex. But with SARS-CoV-2, the virus that causes COVID-19, a simple type of response is all that’s needed to prevent infection. “You just need to trigger an antibody response where the antibodies bind to the surface of the virus and prevent it from entering our cells,” says Ruslan Medzhitov, PhD, professor of immunobiology. “And these types of vaccines tend to be extremely safe.” In addition to the inherent safety of this kind of “training” for the immune system, experts emphasize that the expedited timeline of COVID-19 vaccine development is not a reflection of lax safety standards. “Before a vaccine is approved, it goes through a rigorous amount of testing for safety and efficacy,” says Iwasaki. “So, once a vaccine is made to be publicly available, we should be lining up.” Watch this video to learn more about the fundamentals of how vaccines work, how they are developed, and the importance of vaccination for public health.
Stroke is far more common than you might realize, affecting more than 795,000 people in the U.S. every year. It is a leading cause of death and long-term disability. Yet until now, treatment options have been limited, despite the prevalence and severity of stroke.
Not so long ago, doctors didn’t have much more to offer stroke victims than empathy, says Kevin Sheth, MD, Division Chief of Neurocritical Care and Emergency Neurology. “There wasn’t much you could do.” But that is changing. Recent breakthroughs offer new hope to patients and families. Beating the Clock Think of stroke as a plumbing problem in the brain. It occurs when there is a disruption of blood flow, either because of a vessel blockage (ischemic stroke) or rupture (hemorrhagic stroke).
In both cases, the interruption of blood flow starves brain cells of oxygen, causing them to become damaged and die. Delivering medical interventions early after a stroke can mean the difference between a full recovery and significant disability or death. Time matters. Unfortunately, stroke care often bottlenecks in the first stage: diagnosis. Sometimes, it’s a logistical issue; to identify the type, size, and location of a stroke requires MRI imaging, and the machinery itself can be difficult to access.
MRIs use powerful magnets to create detailed images of the body, which means they must be kept in bunker-type rooms, typically located in hospital basements. As a result, there is often a delay in getting MRI scans for stroke patients. Dr. Sheth collaborated with a group of doctors and engineers to develop a portable MRI machine. Though it captures the images doctors need to properly diagnose stroke, it uses a less powerful magnet. It is lightweight and can be easily wheeled to a patient’s bedside.
“It’s a paradigm shift – from taking a sick patient to the MRI to taking an MRI to a sick patient,” says Dr. Sheth. Stopping the Damage Once a stroke has been diagnosed, the work of mitigating the damage can begin. “Brain tissue is very vulnerable during the first hours after stroke,” says vascular neurologist Nils Petersen, MD. He and his team are using advanced neuro-monitoring technology to study how to manage a patient’s blood pressure in the very acute phase after a stroke.
Dr. Petersen’s research shows that optimal stroke treatment depends on personalization of blood pressure parameters. But calculating the ideal blood pressure for the minutes and hours after a patient has a stroke can be complicated. It depends on a variety of factors—it is not a one-size-fits-all scenario. Harnessing the Immune System Launching an inflammatory reaction is how the body responds to injury anywhere in the body – including the brain, following stroke. However, in this case, the resulting inflammation can sometimes cause even more damage.
But what if that immune response could be used to the patient’s advantage? “We’re trying to understand how we can harness the immune system’s knowledge about how to repair tissues after they’ve been injured,” says Lauren Sansing, MD, Academic Chief of the Division of Stroke and Vascular Neurology. Her team is working to understand the biological signals guiding the immune response to stroke.
That knowledge can then direct the development of targeted therapeutics for the treatment of stroke that minimize early injury and enhance recovery. “We want to be able to lead research efforts that change the lives of patients around the world,” says Dr. Sansing.
Learn about these developments and more in the video above.
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As the world waits for a potential COVID-19 vaccine, we delve into how vaccines actually work. What are the different types of vaccine? How do they trigger and train the immune system, and what is the role of herd immunity?
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