Influenza: Are We Ready or Does The Shot Do Any Good?

Influenza

Influenza activity in the US began to increase in early November 2017 and rose sharply from December through February 3, 2018. From October 2017 to January 1, 2018, the weekly percentage of deaths from pneumonia and flu ranged from 5.8% to 10.1% and has exceeded the epidemic threshold for five consecutive weeks. During seasons with increased severity of influenza, antiviral medications are an important adjunct to vaccinations. Additional study is needed to see if this year's virus will mutate and develop resistance to the four antiviral medications available. In addition to seeing just how effective the current influenza vaccination will be in controlling influenza transmission (Budd et al, 2018).

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In 2018 it will the 100th anniversary of the 1918 influenza pandemic. This event caused an estimated 50-100 million deaths worldwide. A medical student from that time frame described what it was like to care for those patients from the pandemic. This is a big concern for another influenza pandemic-worse-case scenario. In the 2008-2009 H1N1 pandemic found the vaccine had a negligible effect. During the first wave of the pandemic, the US didn’t have any pH1N1 vaccines. This problem continued for most of the second wave as well. According to the CDC, the vaccination affected only 2% to 4% of all pandemic cases, hospitalization and deaths nationwide. Millions of doses arrived too late to do much good and had to be destroyed. All other countries had similar experiences or worse.

And now…
US Department of Health and Human Services released an update with federal officials estimate that a severe pandemic would cause almost six million hospitalizations and 770,000 deaths. Until recently influenza A (H5N1) virus had been regarded as the primary threat to cause the next pandemic. Now, however, it is felt that influenza A (H7N9) pandemic is more likely. And although antiviral drugs specific for influenza vaccines will be available in developed countries, they will be largely unavailable in the rest of the world. And some of these drugs might target the host response but not the pandemic virus.

This study also found that they could not find any recommendations for research the host response. These places are responsible for pandemic and epidemic preparedness and they didn’t have any research in process to check this important factor. Host response is how the antibodies of the infected person attack the virus causing it to mutate as it passes on to the next host. Unfortunately, this testing will have to be financed by public agencies or non-government organizations. Pharmaceutical companies will not support research on off-patent drugs in which they have no commercial interest. It is a sad commentary on the pharmaceutical companies that they are more interested in making a buck than helping to prevent loss of life (Fedson, 2018).

What is influenza and how ready are we?
Influenza is a contagious acute respiratory disease that causes seasonal epidemics with three to five million hospitalizations and 250,000 to 500,000 deaths annually worldwide. Although influenza viruses can cause disease in any age group, the mortality rate is higher among those who are 65Currently older.

Currently licensed vaccines to contain components of three out of four strains responsible for seasonal epidemics and they are changed annually depending on the global surveillance data. Even during years of a good match between vaccine and the circulating strains, vaccine effectiveness in preventing influenza illness may vary among vaccine recipients. Over the past few years, new methodologies have made it easier to understand the host mutation factor and how it contributes to the efficacy of the vaccines.

Even though strain-specific neutralization antibodies confer protection against infection with match influenza virus, studies have shown it can lessen the effect of a similar but different strain. However, it continues to show a greater benefit for younger patients than those 65 yrs and older. It is thought that there should be a different stronger vaccine primarily for that age group (Castiucci, 2018).

And still we struggle…

Each year the influenza vaccine is given with the hope that it will cover the strain of influenza circulation. This virus mutates and evolves quickly in those infected. As it spreads from person to person a small proportion will pass these mutations on and start a new infective strain. Recent advances in sequencing are helping to measure within-host genetic diversity. However it still is difficult to determine linkage among these mutations. The vast number of those afflicted by influenza is of an acute nature; sick and recover quickly while there are those who can suffer from the virus for multiple weeks.

Human influenza virus undergoes antigenic drift and on occasion the shift is on a global scale. Vaccination status did not seem to affect viral sequences suggesting infections in vaccinated individuals were caused by a strain different from what the vaccination covered. By studying how influenza evolves in humans researchers can determine what evolutionary and epidemiological forces transform within-host genetic diversity into global variation. It is important to develop methodologies to systematically to analyze within-host evolutionary dynamic and their relationship to global evolution (Xue et al, 2018).

Severity of having the flu

Influenza vaccinations are the primary strategy for prevention of influenza infection; recommended for people from six months and older. These infections of the flu can vary from mild to severe community-acquired pneumonia. Due to rapid mutation and other variations in the flu virus year to year around the world annual vaccinations are needed to provide protection. In this study 1951 hospitalized patients with community-acquired pneumonia were included in the analysis and 831 or 43% reported having had received the influenza shot for that season before they were hospitalized.

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The study suggested that the seasonal flu vaccine may not be effective in preventing hospitalization due to influenza community-acquired pneumonia. Important implication also says that while vaccines may be a primary prevention strategy they are not 100% effective. The study data also showed that while some of their results were in contradiction of some CDC results that was felt to be because the study only looked at a specific group while CDC looks at data from all groups. In addition, the researchers also said that while they didn’t find the vaccine useful for prevention of hospitalization due to influenza community-acquired pneumonia it may be good for other outcomes. The researchers also found it did have supporting evidence that vaccine effectiveness varies substantially from year to year and that results from studies may not estimate true effectiveness either.

Vaccine effectiveness estimates for various outcomes should continue to be studied on an annual basis. Potential mechanisms of interaction between vaccine uptake and outcomes such as severity of disease, time to clinical improvement, length of hospital stay, clinical failure and short-term and long-term mortality. The potential won’t be realized unless it is studied (Chandler et al, 2018).

Conclusion

Influenza viruses cause respiratory infections typically during the winter months. The two most common ones are influenza A & B. Each season they can go through mutation leading to a new sub are then what can lead to an epidemic or even a pandemic outbreaks. Each year influenza virus infection affects 5% to 20% of global populations. While there continues to be an uncertainty of whether the shot does any good, it is still highly recommended by doctors for people with respiratory disorders.

Asthma is the most common underlying disease in patients with influenza admitted to the hospital in both adults and in children. Influenza and other viral respiratory infections can greatly influence the chance of asthma patients to end up hospitalized during the flu season. Yet their research found low vaccination rate among those with respiratory disorders in both the European Union and the US. Part of this resulted from the recent 2008-2009 H1N1 flu outbreak that led to people contracting an auto immune disorder called Guillian Barré Syndrome. National Institute of Health has even reported that there has been an increase in GBS seen in countries where the vaccine for Zika has been given (NIH, 2018). More often than not, the vaccines contain the prevalent virus strain so coverage is suboptimal at best (Schwarze et al, 2018).

Works Cited
Budd, A. P. et al. (2018). Update: Influenza activity-US. MMWR-Morbidity and Mortality Weekly Report, 67(6). Centers for Disease Control and Prevention (CDC).

Chandler, T. et al. (2018). Effectiveness of the influenza vaccine in preventing hospitalizations of patients with influenza community-acquired pneumonia. The University of Louisville Journal of Respiratory Infections, 2(1), Article 6.

Castrucci, M.R. (2018). Factors affecting immune responses to the influenza vaccine. Human Vaccines & Immunotherapeutics,14(3).

Fedson, D.S. (2018). Clinician intiated research on treating the hosp response to pandemic influenza. Human Vaccines & Immunotherapeutics, 14(3).

NIH (2018). What is Guillain Barré Syndrome? National Institute of Neurological Disorders and Stroke.

Schwarze, J. et al. (2018). Influenza burdens, prevention, and treatment in asthma-a scoping review by the EAAC 1 influenza in asthma task force. Allergy,73(6).

Xue, K. S. et al. (2018). Within host evolution of human influenza virus. Trends in Microbiology,26(9).

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