This afternoon, President Biden is expected to announce a new requirement for federal workers to either be vaccinated or submit to strict testing protocols. CNN has called this anticipated announcement and the recent CDC reversal on mask recommendations “emergency actions designed to contain a new surge of Covid-19 that has quickly become the top issue confronting the White House.” The mandate for federal employees mirrors recent activity across the public and private sectors, as more organizations have announced delays in return-to-work policies and new requirements around transmission mitigation protocols, including vaccination.
This week alone, several private and public sector announcements about vaccine requirements have made headlines. On Monday, the Department of Veterans Affairs announced a vaccination requirement for workers, as did the states of California and New York. On Wednesday, Google notified employees that all workers coming on campus would need to be vaccinated in the coming weeks, with a target return to office date now being pushed back to mid-October. The same day, Lyft announced employees would not be required back in the office until February, while Twitter announced the indefinite postponement of office reopenings in New York and San Francisco. (Tech-focused media company Protocol is tracking announcements from large companies primarily in the tech space: see their latest calendar of return-to-work dates and requirements here.)
Return-to-work precautions and vaccine-related requirements are not limited to federal entities or the tech industry. Earlier this summer, airline giants Delta and United announced that they would require proof of vaccination status for new employees. Similarly, big banks such as Morgan Stanley and Goldman Sachs have required employees to report vaccination status before returning to work.
These policies are not surprising given the increasing momentum of the COVID Delta variant, which now accounts for 82.3% of cases in the U.S. For the week ending July 25, the U.S. saw a 131% increase in new COVID cases overall. In the midst of these Delta-related trends, vaccine manufacturer Pfizer has released early stage data suggesting that a third dose of the COVID vaccine could significantly boost antibodies capable of targeting the Delta variant. The rise in vaccine-related requirements, reports of breakthrough Delta infections among the vaccinated, and research into vaccine efficacy against COVID variants all highlight the importance of understanding how the human immune system and vaccines work together, and how people can work together, to protect against COVID and future threats.
How does the human immune system work?
The human immune system is arguably the most complex system in the human body. It has many components that interact with each other in a cascade to protect from microbial threats. When the immune system is working well, these threats are neutralized without ever causing alarm. When the immune system is not functioning properly, it overreacts to threats, causing autoimmune diseases, cancers, inflammation, and other problems. To appreciate the complexity of the immune system, it’s important to understand the three types of immunity:
- Innate immunity is the body’s response to a foreign attack. This response employs multiple types of cells: lymphocytes, phagocytes, macrophages, mast cells, neutrophils, eosinophils, basophils, natural killer cells (NK), and dendritic cells. These cells work together in what’s called a complement cascade. When they sense a foreign attack, they spring into action to destroy the foreign body before there is an active infection. The Kahn Academy has a great tutorial on this innate response mechanism.
- Adaptive immunity (acquired immunity) relies on white blood cells called lymphocytes to understand what is foreign versus what is not and respond accordingly. The innate immune responses act as a first line of defense and enlist the help of adaptive immunity when a more sophisticated counter-attack is needed, since the adaptive immune response can be very specific to the pathogen that induced it. Using two different classes of lymphocytes called T-cells and B-cells, the adaptive immune system can counter the effects of foreign attack (or antigen) with two different response types. In an antibody response, B-cells will secrete antibodies that bind to and inactivate the antigen. In a cell-mediated response, T-cells will react directly to a virus-infected cell by killing it or signaling macrophages to destroy the invading microbes. Should the antigen appear in the body again in the future, the adaptive immune system will remember and recognize it having acquired familiarity with the antigen from past encounters.
- Passive immunity occurs when individuals receive adaptive immune antibodies from someone else. The most common example of passive immunity is transmission of immunity from mother to baby. Passive immunity is also achievable through drugs that provide adaptive antibodies to a person early on during an infection, enabling faster fighting with fewer symptoms.
While these three types of immunity may seem straightforward, how a human immune system will spring into action against a foreign invader remains difficult to predict. COVID has provided countless examples of this unpredictability, with some infected individuals being asymptomatic and others rapidly deteriorating to the point of hospitalization or even death. However, with the efficacy of currently available vaccines ranging from 72% to 95%, the best way to ensure immune systems are set up for success if exposed to COVID is to receive a vaccine.
How does a COVID vaccine work with the human immune system?
COVID vaccines partner with the adaptive immune system to bolster the T-cells’ and B-cells’ ability to recognize and fight the virus. The vaccines equip the immune system with this information in a number of ways, depending on the vaccine type. Currently, the vaccines approved and available in the U.S. fall into two categories: mRNA (Pfizer and Moderna) and carrier or vector (Johnson & Johnson).
According to the CDC, mRNA COVID vaccines (like the shots available from Pfizer and Moderna) contain genetic material (messenger RNA or mRNA) from the COVID virus, and this material gives cells “instructions for how to make a harmless protein that is unique to the virus.” This protein is often called a “spike protein.” Having made copies of that virus-specific protein, the cells destroy the genetic material provided by the vaccine. The body is now able to recognize the virus protein and builds the lymphocytes (T-cells and B-cells) necessary to fight the COVID virus if contracted.
By contrast, carrier or vector vaccines (like the single shot available from Johnson & Johnson) use a different, harmless virus as a carrier or shell to deliver genetic material specific to the COVID virus. This genetic material is called a “viral vector.” The CDC explains that once this “viral vector” is inside the human body, a similar process of cellular copying and training ensues to build up the lymphocytes that can fight COVID.
While the delivery mechanisms, efficacy, and dosage for vaccines may vary, they share the important function of enabling the adaptive immune system to recognize and neutralize threats. Experts continue to study how vaccines will interact with viral mutations like the COVID Delta variant. However, their message remains clear: those who are able to receive vaccines should get vaccinated – particularly since it is hard to foresee how well an immune response to COVID will fare unaided by a vaccine.
Why does COVID affect people so differently?
The simple answer to this question is that there isn’t yet enough understanding of COVID to explain the wide range of immune responses, from asymptomatic to fatal. However, the principle holds that just as each person is genetically unique, so is each person’s immune system. Consequently, different immune systems respond to the same viral threat in different ways. Despite these unknowns and inherent variability in immune response, experts have identified that COVID induces a major inflammatory response in severe cases. This inflammatory response is a critical layer in the human immune system. When suppressed, the lack of response results in patients who are immunocompromised. When unchecked, an inflammatory response can exacerbate illness and cause ongoing, unhealthy inflammation. Enabling an appropriate level of inflammatory response requires providers to know when to allow the inflammation and when to tell the body to calm down: it’s a very fine line between the two.
Researchers have found that in patients experiencing severe COVID cases, the immune system has gone into overdrive, creating what is called a “cytokine storm.” Cytokines are cell-stimulating molecules, and Dr. Aiko Iwasaki, an immunobiologist at Yale, explains, “Instead of helping the host cope with the infection, the cytokines can cause damage to the tissue, such as breaking down protective lining of the lung and the blood vessels.” This damage can disrupt oxygen exchange in the lungs, causing the shortness of breath and difficulty breathing that many COVID patients report. According to Dr. Iwasaki, the key to being able to fight COVID in the future will be to identify the immune responses required to combat the virus effectively and then find ways to promote those responses through vaccination and other drug interventions.
What do the changes this week mean for the future?
President Biden’s announcement today and other announcements this week have underscored that the U.S. is not yet out of the woods when it comes to COVID. With policy shifts and recommendation reversals likely to continue, it is clear that change will remain the one constant of this global pandemic. Effective risk mitigation strategies will similarly remain absolutely essential.
This crucial risk mitigation falls into two categories: mitigation that relies on human behavior and mitigation that can be independent of human behavior. In the first category, vaccination remains the strongest driver of best outcomes. In the ongoing efforts to increase vaccination and drive toward herd immunity, other behaviors like wearing masks, washing hands, and social distancing have proven effective throughout COVID to help slow or reduce viral transmission. However, relying on human behavior alone can be dicey. As the CDC has repeatedly recommended, mitigation strategies should be layered. That layering requires addressing both human and environmental elements – because communities, organizations, and countries cannot rely on human behaviors alone to fight the pandemic. Effective surface and air disinfection, particularly for shared and indoor spaces, are a critical tool for slowing or even stopping the spread of infectious diseases, including COVID.
The answer to effective disinfection doesn’t lie in more chemicals, wipes, and spraying devices. It lies in the sustainable implementation of UV-C light, which delivers greater efficacy and generates less waste than traditional chemical disinfection. In a world where the COVID virus and other pathogens are evolving, the tools to fight them must also evolve. R-Zero remains committed to meeting the urgent and apparent need for innovation in the disinfection space. Now more than ever before, it is clear that people deserve and should expect better. Regardless of what variants may come, what policies may change, or what other pandemic-like threats may emerge, layered mitigation strategies that address both human behavioral and environmental factors will be the key to fighting COVID now and other pathogenic risks in the future.
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