New vaccine technology aids speedy development
Q: I don't think I'm the only one wondering how the new coronavirus vaccines got developed so fast when other vaccines in the past took so much longer. Can you please explain?
A: When the quest for a safe and effective coronavirus vaccine began, early in 2020, we had only previous vaccine development to guide our expectations. And you're correct, those vaccines - against diseases such as polio, measles, smallpox and chickenpox - took years, or even decades, to develop.
Until now, the fastest timeline was the four years it took to develop the mumps vaccine. Yet less than a year into the current effort, two highly effective preparations have received emergency-use approval from the Food and Drug Administration. This is due to multiple factors. A crucial one is international cooperation, which resulted in the immediate sharing of the genetic sequence of this never-before-seen virus. Additionally, the global health crisis prompted abundant funding.
But perhaps most important was the nature of the virus itself. Coronaviruses get their name from the distinctive "crown" of club-shaped spike proteins on their outer surface. Thanks to years of previous research, we know the virus uses these proteins to enter human cells. Also immensely helpful was the fact that COVID-19 is quite similar to SARS and MERS, each of them coronaviruses that also originated in animals and jumped to humans. In developing the new coronavirus vaccines, scientists were building on an existing body of knowledge.
Unlike previous vaccines, which used a weakened or inactivated virus to trigger an immune response, the new vaccines harness the molecular building blocks of the novel coronavirus. Specifically, they use a single strand of genetic code known as messenger RNA, or mRNA. The genetic code teaches human cells to build a harmless fragment of the spike protein, just enough for the immune system to recognize the coronavirus. This triggers a robust response that deactivates the spike protein. Because that spike protein is how the coronavirus penetrates a cell, disabling it prevents infection. And, because there are multiple ways to deploy mRNA, multiple vaccines are now in different stages of development. That's also why, when you get the first of the two-dose vaccine regimen, you have to follow up with the same vaccine. You can't mix and match.
Both approved vaccines have impressive efficacy of 94% to 95%. The numbers are a bit lower for people 65 and older, but it's believed that may reflect the smaller sample size of clinical trial volunteers in that age group. As with many vaccines, this one has several side effects. Some people receiving the shots report experiencing pain at the injection site, headache, fatigue, pain in the muscles or joints, chills and mild fever. Several people have experienced severe reactions to the vaccine, but those cases were rare.
These new coronavirus vaccines are game-changers. In light of the dangers posed by COVID-19, as well as the lingering effects of the illness, we hope that when the vaccine becomes available to you, you will choose to get immunized.
Q: Our dad is 67 years old and just got a diagnosis of mild cognitive impairment. His doctor told us that getting regular exercise can help. I've never heard this before. Is there a scientific basis, or is the idea just for dad to stay healthy?
A: Mild cognitive impairment, also referred to as MCI, is a worsening of the skills we use to learn, reason and remember. It affects up to one-fifth of adults over the age of 65. Although, as the name of the condition suggests, the changes to cognition are slight, they are, nonetheless, noticeable. People with mild cognitive impairment are also at increased risk of developing various types of dementia, including Alzheimer's disease.
An area of study that continues to generate great interest is the beneficial effects exercise may have on cognition and dementia. Research that analyzes years of health and behavior data collected from specific groups of people has found that individuals who exercise regularly can measurably reduce their risk of developing dementia when they age. There is also evidence that these protective effects can carry over to people who continue to exercise in their later years.
A new study, published in November in the journal Alzheimer's Research and Therapy, found people with MCI who did even a modest amount of exercise each day could be helping to delay the onset of more cognitive decline. Researchers examined health data collected from almost 250,000 people over the course of six years. The majority were between the ages of 65 and 70 and had been diagnosed with mild cognitive impairment. The subjects were divided into four groups: those who never exercised, those who had just begun to exercise, those who had recently quit exercising and those who had exercised prior to their diagnosis and continued to exercise regularly. Each of the groups self-reported the data about their physical activity.
Among the findings was that, when compared to the group that never exercised, those who had exercised prior to and after their diagnosis of MCI reduced their risk of progressing into dementia by 18%. For those study subjects who had begun regular exercise after receiving their diagnosis of MCI, the risk of progressing to dementia decreased by 11%.
When it came to defining physical activity, the researchers set the bar pretty low. They classified it as 10 or more minutes of moderate or vigorous exercise done more than one day per week. Not that surprisingly, they also found that exercising longer and more often conferred increased benefits. The scientists surmised exercise may have protective effects because it raises the levels of certain proteins in the brain, which help with neuron development and maintenance. They also suggested a link to the increase of blood flow to the brain during exercise. When physical activity ceased, so did the positive cognitive effects it conferred.
As with all studies with self-reported data, the conclusions rely on the accuracy of the participants' record-keeping. Still, the physical and mental health benefits of regular exercise are well known. An exercise program tailored to your dad's health and abilities could be helpful.
• Dr. Eve Glazier is an internist and associate professor of medicine at UCLA Health. Dr. Elizabeth Ko is an internist and assistant professor of medicine at UCLA Health. Send your questions to askthedoctors@mednet.ucla.edu.