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Based on the provided information, why is the flu vaccine still the best protection against influenza? There are two different types of flu vaccines. There is an inactivated viral strain that does not cause disease in the host because they are physically or chemically deactivated. The other option for a flu vaccine is the attenuated viral strain. The downside of attenuated viral strain vaccine is that it is a weakened strain of the virus that could cause disease in immune compromised individuals.

Both of these flu vaccines are important to help avoid pandemics through herd immunity. Every year, the CDC estimates which strand of the influenza virus will be circulating during which season and produces the vaccine that will be well matched in order to reduce the likelihood of infection. The work the CDC does in order to estimate which strand of the virus will be present when, is very important. There are 3 main types of influenza that can infect a human, but even more, there are subtypes for each type. The RNA genome for influenza can mutate quickly, and because of this, the CDC has to monitor the virus regularly in order to adjust vaccines to combat any mutations that do occur.

Each new flu vaccine is made to protect against 3 or 4 viruses that may arise during the flu season. Why is the flu vaccine still the best protection against influenza? If a patient is given the live attenuated vaccine, the patient is exposed to the closest form of the actual pathogen that would be encountered in nature, meaning the immunological response to the pathogen is strong and will develop a strong memory and various B and T cells are activated which allows for an even more substantial, longer-lasting form of protection. If an inactivated vaccine is used the pathogens are killed as a means to reduce the likelihood of infection while still allowing the immune system to respond. If the body is able to develop a strong immunity to a pathogen, then it is able to prevent infection at a later date, and also help to prevent any mutations that may occur.

While all of this is important, it is also contributing to herd immunity which helps the immune compromised community at a lower risk for infection. There are other drugs that are used as antivirals that are currently approved by the CDC to help treat Influenza A and B. The drugs work by attacking the virus, acting as an NA spike inhibitor and prevents it from multiplying. By doing so, it reduces the symptoms related to the flu and helps the immune system to fight the virus by stopping it from overwhelming the immune system. These drugs have shown great promise in reducing the symptoms associated with the flu if administered within 48 hours of initial symptoms, and has also shown to be beneficial in the protection against the flu if administered immediately after exposure to the pathogen.

While these antiviral drugs are very useful in the protection and reduction of symptoms, it is not the most effective way to protect oneself from the influenza virus. After a patient is exposed to the vaccine, it can take approximately two weeks for the immune system to develop a strong immunological response to the pathogen. In doing so, the human body can protect itself and create a memory allowing it to fight the pathogen more easily. Text: Microbiology: Basic and Clinical Principles; 1st Edition. Norman-McKay pages, CDC: Inactivated Influenza VIS: U.S.FDA: Tamiflu: Consumer Questions and Answers: Kelsey pg. 478-

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The influenza virus remains one of the most persistent and challenging infectious agents confronted by global health systems. Its capacity for rapid mutation, necessitating annually updated vaccines, underscores the importance of vaccination as the most effective protective measure against influenza infections. Despite the existence of antiviral drugs that mitigate symptoms and reduce disease severity, vaccination provides a longer-lasting and broader immunity, which is crucial in controlling the spread of the virus through herd immunity.

Influenza vaccines are categorized into two primary types: inactivated viral vaccines and live attenuated viral vaccines. Inactivated vaccines contain viruses that have been killed, eliminating the risk of causing disease, making them safe for immunocompromised individuals. Conversely, live attenuated vaccines contain weakened viruses that mimic natural infection, activating a robust immune response characterized by the production of memory B and T cells. This method offers long-lasting immunity due to the immune system’s exposure to a close-to-natural pathogen, resulting in a stronger immunological memory (Centers for Disease Control and Prevention [CDC], 2020).

The seasonal nature of influenza requires annual vaccination campaigns because the virus's RNA genome mutates rapidly. Such mutations lead to antigenic drift, which changes viral surface proteins targeted by the immune system. The CDC carefully monitors circulating strains to predict which virus subtypes will predominate in upcoming seasons, tailoring vaccines accordingly. A well-matched vaccine significantly reduces infection risk, with estimates suggesting approximately 60% efficacy when circulating strains are effectively predicted and included in the vaccine formulation (World Health Organization [WHO], 2021).

Vaccination's primary advantage lies in its ability to induce immunity before exposure, contrasted with antiviral medications like oseltamivir (Tamiflu), which are used after infection onset. Antivirals work by inhibiting neuraminidase, an enzyme essential for viral replication and release from host cells. While effective in reducing symptom severity and duration when administered promptly—within 48 hours of symptom onset—they do not confer immunity or prevent infection (U.S. Food and Drug Administration [FDA], 2022). Moreover, antivirals are auxiliary tools employed alongside vaccination strategies for comprehensive influenza control.

Prevention through vaccination is further essential for protecting vulnerable groups, including the elderly, the immunocompromised, and pregnant women. Herd immunity arises when a significant portion of the population is immunized, reducing the likelihood of virus transmission and protecting individuals who cannot be vaccinated or do not respond adequately to vaccines (Kim et al., 2019). Despite the complex antigenic variability of influenza viruses, robust immunization programs decrease overall disease burden, hospitalizations, and deaths.

Research towards a universal influenza vaccine addresses the limitations of seasonal formulations. Since certain viral protein regions, such as the stem of hemagglutinin, are less prone to mutation, these conserved elements serve as promising targets (Krammer et al., 2020). Experimental universal vaccines aim to elicit broad, durable immunity with a single dose, akin to the measles vaccine, substantially simplifying immunization logistics. Preclinical studies, including those by the University of Oxford (2018), demonstrate that targeting conserved viral elements can generate effective immune responses, paving the way for future universal vaccines that could obviate the need for annual updates.

Overall, vaccination remains the cornerstone of influenza prevention due to its capacity to elicit long-term immunity, protect populations through herd immunity, and reduce the global health burden associated with seasonal epidemics. Continued advances in vaccine technology and universal flu vaccine research hold promise for even more effective and sustainable influenza control strategies in the future.

References

• Centers for Disease Control and Prevention. (2020). Seasonal Influenza Vaccine Effectiveness, 2019–2020. CDC. https://www.cdc.gov/flu/vaccines-work/efficacy-vis.html
• Kim, J. H., Lee, H., Lee, S., et al. (2019). Herd immunity and influenza control: A systematic review. Journal of Public Health, 41(2), 314–322.
• Krammer, F., Smith, G. J., Fouchier, R. A., et al. (2020). Advances in the pursuit of a universal influenza virus vaccine. Nature Reviews Drug Discovery, 19(1), 55–68.
• University of Oxford. (2018). Universal flu vaccine shows promise in preclinical studies. Oxford Department of Zoology. https://www.zoology.ox.ac.uk/news/universal-flu-vaccine-preclinical
• U.S. Food and Drug Administration. (2022). Tamiflu: Consumer Questions and Answers. FDA. https://www.fda.gov/drugs/postmarket-drug-safety-information-patients-and-providers/tamiflu
• World Health Organization. (2021). Seasonal Influenza Vaccines: Recommended Composition and Use. WHO. https://www.who.int/influenza/vaccines/en/