Contributed by: Brooke Barlow, Rachel Wade, and Yeseulmi Lee
How Microbes Could Be Used in Skin Care and Makeup Products
Contributed by: Brooke Barlow, Rachel Wade, and Yeseulmi Lee
How Microbes Could Be Used in Skin Care and Makeup Products
Contributed by: Chelsey A. Skeete, Emily F Ursini, and Sopjia T. Noble
The gut microbiome is an incredibly complex component of the body that is still not fully understood. The microbiome can be impacted by a vast number of factors including diet, exercise, contact with others, and time spent in and outdoors (7). The gut microbiome is
impacted by the environment, which is influenced by temperature and climate (8).The temperature influences microbial diversity in a multitude of ways from common seasonal changes to the earth’s overall shift in climate (8). This is especially important to consider when thinking about the 70 million Americans currently suffering from gastrointestinal issues including irritable bowel syndrome and celiac disease (6). The information to follow explores some beneficial and detrimental influences of temperature on the gut microbiome, which are incredibly important to keep in mind when assessing the impact that temperature shift will have on the environment, as well as how to maintain a healthy microbiome throughout these changes.
The Dangerous Effects of Temperature and Environment Change on the Microbiome
Growing up in microbe-rich environments, individuals can uptake microbes from the environment that colonize in the gut as commensal bacteria. Urbanization often leads to loss of biodiversity and local habitats that would be reservoirs for commensal bacteria to survive and reproduce (8). Individuals who grow up in environments with slightly lower microbial diversity are exposed to less potential commensal bacteria. Less exposure to commensals especially during child development may raise individuals’ risks for inflammatory diseases. Additionally, reduced exposure to pathogenic bacteria may result in defective or compromised immunoregulation.
In a study with mice samples, the populations raised in cold environments for several days had intestinal structural changes that enabled them to have increased glucose uptake (4). The increased presence of glucose led to higher production and functioning of insulin to be recruited to the small intestine to break down glucose. Overuse of insulin led to insulin sensitivity in the mice, which raises the risks of the mice getting Type II Diabetes. These mice could also be a model for cold temperature impact on humans and how their small intestines could similarly alter to have increased glucose uptake leading to insulin sensitivity. Of course other factors must be considered in this relationship of temperature and insulin sensitivity, as diet and genetic predisposition to Diabetes would impact the results seen in humans as well. In warm, heat stressed environments, the diversity in the gut microbiome has decreased in cow subjects (11).
The Beneficial Effects of Temperature Change on the Microbiome
Cold exposure may lengthen microvilli in the small intestine where commensal bacteria may attach and grow (3). Additionally, cold exposure may improve glucose absorption in the small intestines of humans enabling more carbon resources for commensal bacteria to survive and reproduce in the gut (3). During rapid temperature changes, some species in the gut microbiota may produce heat to help animal hosts maintain their internal temperatures in cold environments (9).
One research group researched how temperature affects microbial diversity in feces and cecum samples of mice (4). Some mice were raised in room temperature or cold environments for up to 31 days and their fece samples were collected to sequence the DNA in each sample. In room temperature environments there tends to be a higher abundance of Verrucomicrobia across the feces and cecum samples. However, there is a slightly higher abundance of Deferribacteres in samples isolated from mice raised in colder environments. Such evidence demonstrates that the populations of bacteria in mammals’ microbiomes may slightly change due to extreme temperature changes in the environment. This change may be due to the fact that certain bacteria based on its structure and functions can only adapt to specific temperature ranges. These mice used in this experiment may possibly be a model for the human gut microbiome and how it may be subject to change in its diversity due to extreme temperature changes.
Tips to Maintain the Diversity and Viability of the Gut Microbiome
There are quite a few studies that show how cold environments may both positively and negatively impact the gut microbiome of mice, salamanders and other animals. In these temperatures, the phyla composition of bacteria change over time due to certain selective pressures bacteria may have to survive and reproduce in such an environment. On the other extreme, heat stressors may reduce gut microbiota diversity in animals. However, there are very little research studies that demonstrate how climate change may alter the gut microbiota of humans. While these animals used in these experiments may be models for the effects of climate change on the human gut microbiome, humans have more advanced homeostatic mechanisms to rapidly adapt to environmental changes. There is still more research that needs to be conducted to show if indeed temperature change is harmful to the gut microbiota diversity in humans.
Contributed by: Andres Axline, Teresa Schauer, and Mathew DeNave
Contributed by: Katherine Hayes, Catherine Roughneen, and Darya Kostyuchek
As early as the seventeenth century, both men and women have been utilizing soft fabric or animal hides as a means of fashioning handheld bags to carry their belongings. One early example originating in Scotland is the sporran, a satchel type accessory, that was worn under pocketless kilts. Nowadays, the modern handbag has become just as essential as any other article of clothing. Americans use handbags daily to carry their everyday needs from commuting to work to travelling through a busy airport. Consequently, purses are often kept in environments laden with bacteria, such as kitchen tables, restroom floors, and fast food counters.
It is said that the common handbag hosts more germs than a toilet seat. This is due to the vast diversity of microbiological communities and types of bacteria found both on the inside and bottom of everyday handbags. Admittedly, one probably cleans the inside of their toilet more often than the inside of their handbag. According to a recent study done in 2015 created in order to further investigate the importance of microorganisms living in and on purses shows that pocketbooks and handbags are easily contaminated with infectious agents. Microbiologists have confirmed that about one third of handbags have fecal bacteria on them. Other strains of bacteria found included Staphylococcus, Enterococcus, Escherichia coli, Pseudomonas, and Micrococcus.
These microorganisms themselves can lead to intestine problems, chest disease, or staph infections. Therefore, people carrying around handbags can unknowingly serve as vehicles for the transmission of diseases. Purses in this way are — fomites or vectors of disease for thousands of bacterial colonies festering inside our bags. In the study, 145 handbags, 80 from women and 65 from men, were swabbed and cultured looking for the presence of certain bacteria. Bacteria were then identified by gram staining and other biochemical tests. The scientists found that 138 purses (95.2%) had bacterial contamination, with about half having single bacterial growth and the other half having mixed bacterial growth (Biranjia-Hurdoyal, Susheela D, et al.). Most bacteria found from the study was relatively harmless with the exception of Staphylococcus, Bacillus, and Micrococcus, which are considered opportunistic pathogens, infecting both healthy and immunocompromised individuals. The study also found that women were more likely to have bacterial growth in the handbags than men. This may be attributed to women being more likely to carry a purse in the first place and more likely to place said purse on kitchen tables, public restroom floors or counters. Purse carriers also never completely empty or clean their belongings and tend to keep items inside including food and hand lotions that can initiate vast microbial growth.
Why are Purses such great Fomites?
Handbags are in constant contact with our hands and a variety of surfaces, increasing the risk of germs being transferred to the bag. Once germs are on our handbags, we can easily transfer harmful germs to other people and surfaces.
One study in the United Kingdom found that the handle was the bacterial hotspot, but others report that the inside of the bag was worse, containing items like makeup or hand creams that had the toilet-flush levels of bacteria (Gerba). The inside of handbags create a perfect haven for germs because they can live in a dark, humid, and damp environment with old food crumbs floating around providing nutrients to the bacteria. Overall, scientists seem to agree that the material of the handbag is also an important factor in determining bacterial growth. Handbags with rough, braided, and grooved surfaces harbor more bacteria than handbags with smooth surfaces. This is because the bacteria can harvest themselves inside these small hard to reach places.
Your money, keys, credit cards, and mobile phones inside your handbag are no better. A study done to find the possible transmission of infectious bacteria via mobile phones, swabbed 192 phones and found that 91.7% of them showed bacterial contamination (Bhoonderowa). Furthermore, it was discovered that women’s phones, kept in purses had more colony forming bacteria compared to men’s phones that were kept in pockets. Phones themselves can be considered fomites as we take them with us to the kitchen, the restroom, hospitals, and other places that are chock-full of microorganisms. Similarly, more than 50% of coins and banknotes were found to be contaminated with bacteria. Most items in handbags are passed between many people, placed on surfaces covered with bacteria, and touched by dirty hands. This creates a vicious cycle between bacteria from our handbags contaminating our belongings, and the same belongings making the bacterial growth in our handbags worse.
How Can we Prevent the Breeding Grounds?
These few tips can severely decrease the bacterial count on the bottom and inside of your bags. In fact, the “toilet plume,” or small particles of toxins and waste that mix together with the toilet water, is known to be able to hurl aerosolized feces into the air as high as 15 feet every time they’re flushed without closing the lid. Similarly, one communicable and vomit induced microorganism found in a lot of toilet bowls, C. difficile, can shoot up to 10 inches. As well as keeping food and fruit out of the inside of bags is extremely helpful (Lawton). This is due to the fact that as mentioned above, the insides of purses can be perfect breeding grounds for mold or other microbes that thrive off of dark and warm spaces – not to mention that food naturally have enzymes that catalyze the degradation process (Gerba).
Contributed by: Rafat T. Quazi, Elizabeth E. Spyrou, and Michaela J. Sorrell
The human gut harbors nearly 100 trillion microbes of more than 1,000 different species involved breaking down food, supporting our immune system, and as revealed by current research, have important implications on our mental health. Recent studies have yielded significant evidence of an interaction between our intestinal microbiota and the central nervous system, a connection that has been recognized as the gut-brain axis (GBA). This connection is important when we consider the high comorbidity between gastrointestinal disorders and stress-related psychiatric disorders, such as anxiety and depression. Probiotics, fecal transplants, and altered diets have been recognized as means to manipulate our microbiome and hold potential for the prevention and treatment of prevalent psychiatric diseases in today’s society.
The enteric nervous system, consisting of approximately 100 million neurons embedded in the walls of our gut and acting as a ‘second brain’, is a key player in the GBA. Although it is not entirely known how gut communicates with and influences our brain, one way that it might is through the production of neurotransmitters such as Serotonin which is well-known for it’s role in mood changes. Gut bacteria can also influence the metabolism of these compounds and how much reaches the brain. Another way that gut bacteria can influence the brain is through activation of the vagus nerve. Finally, the gut microbiome may impact the brain through it’s tie to the immune system. Gut microbiota regulate levels of immune molecules like cytokines; elevated levels of inflammatory cytokines have been associated with depression. Gut-brain communication is bidirectional, meaning that patients with gastrointestinal issues have higher rates of depression and anxiety, and patients with mental health issues experience more GI problems than healthy individuals. Early life disruption of the bidirectional GBA has been associated with increased risk of depression in adulthood.
Pros/Cons of dealing with Mental Disorders through a Bacterial Lens
There have been increasing amounts of case studies that serve to inspect the “bidirectional
communication” between the gut and brain, called the gut-brain axis. Scientists have theorized that a decrease in good gut bacteria leads to inflammatory responses in the immune system. This then leads to inflammatory and mental disorders, such as depression.
In the case study “Gut-Brain Axis and Mood Disorder” researchers tested the theory that intestinal microorganisms did played role in affecting the human gut-brain axis (neuro-endocrine immune pathways) and how that could cause certain mood disorders. The study also looked at the effect of pre/probiotics as well as antibiotics on mood disorders.
Previous studies show that ~60% of anxiety/depressed patients suffered from irritable bowel syndrome (IBS) which is involved with changes in intestinal microorganisms, namely a reduction of microbiota species. In fact, a study led by Park AJ, Blennerhassett, and Verdu stated that animal procedures showed gut bacterial disturbances to cause nervous system pain and brain chemistry changes and behavior. Stress can lead to gut bacteria change and therefore mood change with the HPA axis. Corticotrophin-releasing factor (CRF) receptors in the body are used to measure intestinal permeability induced by stress. In acute stress, permeability is increased, and early life stress causes a cortisone level increase which forces bacteria to move towards your liver and spleen, furthering the idea that those with mood disorders suffer from a reduction in gut bacteria. Studies on rats showed that the lack of intestinal microbiota increased anxiety-ridden behavior when the rats were faced with challenges or unknown stimuli.
Probiotic Effects on Stress-related Disorders
While various means of regulating the gut microbiota have been considered, an interest in probiotic treatments has particularly increased in recent years. Probiotics are live microorganisms consumed with the expectation of health benefits, as they have the potential to improve and restore our gut bacteria. It is known that gut bacteria can produce metabolites for various human organ systems. The bacterias Lactobacillus and Bifidobacterium, for example, are able to synthesize gamma-aminobutyric acid (GABA) from monosodium glutamate, which is an important inhibitory neurotransmitter having calming effects in the central nervous system. A significant amount of the research has been done on germ free mice, which are entirely devoid of microorganisms, offering a more controlled setting for observation of the role of the microbiome in diseases and their treatment. In one study, it was found that a bacterium Bifidobacterium infantis, commonly found in probiotics, was able to reverse an elevated HPA-axis response and depression, leading to a general relaxation in neural processes. Other rats who were regularly administered probiotics including Lactobacillus helveticus or Bifidobacterium longum showed decreased psychological stress levels and cortisol levels, a hormone associated with our stress response. Studies on humans have also been able to show connections between specific gut bacteria and depression. For example, the Bacteriodes family has been specifically shown to be associated with depression, with low levels of this bacterium in fecal matter associated with high activity in brain areas related to depression. This makes sense, as this family has been shown to produce large quantities of GABA, which as stated before is among the most significant inhibitory neurotransmitters on the CNS. Based on studies like these, probiotics have the potential to decrease symptoms of anxiety and depression, and therefore may be an important treatment option in coming years. Without the side effects and stigma that surround antidepressants in today’s society, this could be a promising option for people suffering from these psychiatric disorders.
Contributed by: Madison J. O’Connor, Jonathon R. Vickery, and Ernest M. Violet
What Is Permafrost?
Permafrost is soil that has been frozen for at least 2 years. These soils cover about 25% of all
land in the Northern Hemisphere, and they store more than half of Earth’s soil carbon. Permafrost habitats can be 1-3 million years old in the Arctic and bear a variety of microorganisms, many of which remain active at subzero temperatures. This kind of habitat is ideal for keeping microbes and spores dormant, or metabolically inactive, due to its neutral pH, low temperature, and lack of both of light and oxygen.
Permafrost and Climate Change
Climate change is warming the Arctic twice as quickly as any other place on Earth. As global temperatures increase, microbial metabolism of organic carbon increases, which results in the increased production of carbon dioxide and methane. This process leads to a dangerous feedback loop. As more carbon dioxide and methane are released, greater warming occurs, which then releases more carbon dioxide and methane. This cycle results in the activation of dormant microbes present in the permafrost.
Microbes Discovered in Permafrost
Impact on Human Health
The possibility that pathogenic microbes can be revived and infect humans is well-established. What is uncertain is whether these microbes are bacteria that can be fought with antibiotics, bacteria that are resistant to antibiotics, or viruses. Since these microbes have been trapped in permafrost for long periods of time, our immune systems would not recognize them or be able to defend against them. Therefore, these once-dormant microbes could pose a serious threat to human health.
Contributed by: Alison A. Lemme, Kathryn H. Shaffert, and Angel E. Roman
What is a Microbial Fingerprint?
Every individual has their own microbial fingerprint. This means that each individual’s microbiome has a specific makeup of species and strains. This fingerprint is largely determined by a person’s environment. Similarly, a person’s environment is also affected by their microbial fingerprint. This means that there is an exchange occurring between people and their environment as each sheds microbes onto the other. Due to this shedding and exchange, it has been shown that the proportions of bacterial species are in constant flux; however, the overall makeup of microbial strains remained the same (1).
How is Microbial Fingerprint data used?
The data collected from microbial fingerprints is used to learn which microbes are present in the surrounding environment and how they live and function in these specific environmental conditions. These fingerprint methods are very important in the bioremediation field (3), by indicating whether or not bioremediation will be effective for a specific surface depending on the makeup of the microbial population. Bioremediation is the introduction of microbes to break down environmental pollutants! In addition, these fingerprints can account for changes in the microbial community over a period of time or period of bioremediation. They are basically environmental markers that indicate if the bioremediation was successful or not!
Three Microbial Fingerprinting Methods
PLFA: Phospholipid Fatty Acid Analysis
PLFA analysis measures the total biomass of a microbial community and creates a profile or ‘fingerprint’ of its composition, including several microbial species (except for archaea). PLFA analysis is most commonly used to determine how varying conditions impact total biomass (2).
DGGE: Denaturing Gradient Gel Electrophoresis
DGGE amplifies DNA and analyzes its molecular weight to demonstrate how the genetic composition of a microbial fingerprint is altered in varying conditions. These results are extrapolated to identify the family or genus of the organisms present at the highest abundance. Subsequent sequence analysis of the dominant bands provides more information regarding the identity of the abundant species. Because DGGE can only identify the family or genus level of only the most abundant species present, it is typically utilized as a first step in microbial fingerprint identification (2).
T-RFLP: Terminal Restriction Fragment Length Polymorphism
T-RFLP is a qualitative method of microbial fingerprinting that uses restriction enzymes to break apart DNA at sites that are species-specific. Therefore, the lengths of the fragments that are produced are indicative of the specific organisms present (2). T-RFLP is able to detect microorganisms that are present at lower concentrations in a sample than DGGE techniques (4).
Applications of Microbial Fingerprinting
Due to the uniqueness of each individual’s microbial fingerprint, research is being conducted on its possible application as an emerging tool for forensics. Because the average person sheds approximately 15 million bacteria per hour, their microbial fingerprint may be present at a crime scene after their departure for testing by forensic officials. By sequencing the species present at the crime scene, forensic officials are able to create a microbial profile of a suspect.
The proportions of microbial species present also provide a potential opportunity for further specification of the identification of the criminal’s lifestyle, because certain species will thrive more in specific lifestyles (1). While this is still an area of active research, it represents an exciting innovation that can be used to complement traditional methods of identification, such as DNA sequencing, in order to enhance the reliability of identification of perpetrators.
Advantages of Microbial Fingerprints
Microbial fingerprinting methods do not require the growth of a microbe in a laboratory setting. This saves time and resources! These methods can be used to identify and track specific phenotypes of organisms that have never before been cultured or identified (3).
In a global environment where new unknown contaminants are constantly emerging and being produced, microbial fingerprints can be a useful tool. Since very little background information is needed to identify microbial species of interest, these methods can help to track these newly emerging contaminants!
Limitations of Microbial Fingerprints
PLFA analysis is unable to identify specific microorganisms. On the other hand, genetic fingerprinting methods like DGGE or T-RFLP can in fact identify specific microorganisms, but can not always determine the exact number of that microorganism that exists in the given environment (3). Lastly, microbial fingerprints are very detailed, and as a result are very subjective in their interpretation from person to person. The more microbial communities that are analyzed using these methods, the more accurately scientists will be able to identify the microorganisms. So it’s up to us to keep these methods relevant!
Our microbial fingerprints don’t just identify us, they even reveal information about the microbes living in, on, and around us!
Contributed by: Kayleigh S. Clermont, Jeremiah Seo, and Yanlin Zi
Almost everyone loves dogs, cats, and bunnies, but other animals or insects such as wasps, scorpions, and snakes are usually not the “beloved” superstar in the animal world. They are neither cute nor friendly, and moreover, their venom even threatens our health. However, scientists recently have discovered that the venom of these “malicious” creatures could be beneficial to us.
When people hear this sound in their house, most people’s first reaction is “Uh-oh.” Then, perhaps, they would start freaking out and trying desperately to get this annoying intruder out of their house as soon as possible. Admittedly, unlike honey bees, who are both friendly and beneficial workers, wasps are considered mostly as dangerous and frightening. However, scientists have recently found out the wasp’s venom can be extremely beneficial in the field of medicine.
If stung, wasp venom could cause swelling of the skin, hives, and itching as well as many other symptoms. In severe cases, the potent venom could also cause dizziness, breathing difficulties, vomiting, or even loss of consciousness. However, even though wasp venom poses such a threat to human health, it could also help doctors fight some complicated infections.
To begin the research on the medicinal values of wasp venom, Leite et. al did a study in which they studied that the venom of Polybia paulista, a kind of social wasp (wasps that lived in colonies) from South America that is normally found in the tropical areas of Brazil, Argentina, and Paraguay. Researchers found that this specific wasp venom contains a peptide, a small chain of amino acids, that they called Polybia-MP1. They discovered that this peptide could potentially be used as a chemotherapeutic substance. The peptide was observed to have the ability to eliminate cancer cells. However, the exact mechanism of this elimination process is still not fully understood. Just like other animals’ venom, wasp venom contains a multitude of compounds that have the ability to kill various kinds of bacteria. However, in most cases, the venom is so toxic that it cannot be used in humans.
In 2018, scientists from MIT elaborated on the previous studies of Polybia paulista venom with the intention of using it to formulate a drug that could be used on humans. From this study, MIT researchers successfully developed a method to modify the antimicrobial peptides extracted from P. paulista venom so that they would not be toxic to humans but still retain their bacteria-killing properties. To achieve this, scientists extracted a very small amount of the antimicrobial peptide from the wasp venom. De la Fuente-Nunez, one of the scientists from this MIT project, explains, “it’s a small enough peptide that you can try to mutate as many amino acid residues as possible to try to figure out how each building block is contributing to antimicrobial activity and toxicity.”
The modified wasp venom-derived peptide has the ability to kill the bacteria by disrupting the bacterial cell membrane, just like attacking a citadel during a war. The venom-derived drug has already been proven be able to successfully fight against Pseudomonas aeruginosa, a bacteria that commonly causes respiratory and urinary tract infections.
Most people jump at the sound of a snake nearby out of fear of getting bitten and having toxic venom injected into their tissues and bloodstream. Though many snakes are nothing to be afraid of, pit vipers pose a massive threat because of their powerful bite and potent venom. Pit vipers are a family of snakes that are found in various habitats in Europe, Asia, and the Americas. A bite from a pit viper can have many consequences including but not limited to pain, swelling, bruising, numbness, respiratory distress, and shock.
Despite all of these consequences, scientists have found a way to manipulate the venom of the Brazilian pit viper and turn it into a helpful drug for humans. It all started when John Vane tested small amounts of Brazilian pit viper venom on dog lungs in Vane recognized that compounds from the venom inhibited the enzyme that causes high blood pressure. Soon after, in 1974, Squibb, a US drug company, tested the ability of one of the compounds in the venom to lower blood pressure. In 1981, Squibb had an FDA-approved drug which they called Captopril.
By lowering high blood pressure with Captopril, the risk of heart attack, stroke, and kidney issues are all consequently reduced. Captopril does this by easing the blood vessels, thereby allowing blood to flow through more easily. Additionally, some bacterial and viral infections can cause high blood pressure, in which cases, Captopril could be used to treat that symptom. Although Captopril has its benefits, it also has potentially harmful side effects. Some of the consequences of using this drug may include dizziness, fainting, tachycardia (fast heartbeat), muscle weakness, or liver problems.
As seen in the example of the wasp and the Brazilian pit viper, venom of all sorts of animals can potentially be manipulated and used in small doses for medicinal purposes. By targeting species whose venom is not well researched, amazing drugs could possibly be created to target bacterial infections, viral infections, fungal infections, and even maybe cancer. More research needs to be done on species who seem scary because they could actually prove to be helpful to humankind as the wasp and the Brazilian pit viper have.
Contributed by: Nicole Bell, Tara Beckwith, and Kelly Cavan
Vaccines have been a hot topic for scientists, researchers, healthcare professionals, and
parents alike. While many people have learned that vaccines do not cause autism or changes in intelligence, personality, or behavior, there is still a lot of skepticism surrounding them. What really are vaccines, what is being put in my or my child’s body, and why do we need them?
Vaccines protect people against severe or life-threatening diseases that spread easily and have very serious side-effects or a high mortality (death) rate. Vaccines are made by taking the disease-causing bacteria or virus and turning it into a form that is not harmful to the body, also known as an antigen. The antigen does not injure the body, but there is enough
material the body can fight off, and remember how it fought it. This makes the immune response from the body the next time the virus or bacteria comes much more efficient!
Production of Vaccines
Vaccines are made in a five step process: generating, releasing and isolating, purifying,
strengthening, and distributing the antigen: Generating the antigen is the first step, which
is made using one of the processes you will read about in the table below, and then growing the antigen in different cells, including a chicken egg, human cell, or bacteria. Next, the antigen is isolated from the cell where it is grown and is released from it. The antigen is then purified, by filters or by being inactivated, so it can be used on people. After this, the antigen is strengthened by adding adjuvant (which enhances the body’s immune response), stabilizers (to increase the ability of the vaccine to be stored), and/or preservatives (especially if the vaccine is multi-dose). Finally, the antigen is packaged, put in a vessel, and sent out for use (“How Vaccines are Made”).
The type of vaccine used is different depending on the virus and bacteria:
History of Vaccines
Contrary to popular belief, the story of vaccines does not begin with Edward Jenner’s invention of the smallpox vaccine in 1796. Rather, it begins with a long history of infectious disease in humans, and specifically, with early uses of smallpox material to provide immunity against that disease (“All Timelines Overview”).
U.S. Vaccine Licensing in the Latter Half of the 20th Century:
21st Century Innovations, Events, and Outcomes:
Contents of Vaccines
The contents of vaccines can be broken up into a few categories:
Vaccines have a long-standing history as life-saving inventions. Using the body’s own
processes to create an immune response and recognition, vaccines allow people of many different states of health to protect themselves from diseases that could normally kill them. Vaccines will only improve over time and will remain a safe and effective way of keeping the body protected from many dangerous bacteria and viruses.
Contributed by: Zainab Abbasi, Samantha Murphy, and Andrew Casey