‘Is the human body not capable of dealing with the flu without any preventive medication?’.
Flu (influenza) is a seasonal disease, typically prevalent in winter in the US. Many among the unvaccinated contract and survive the flu each year suggesting many humans are capable of dealing with it without preventive medicine. However, flu strains tend to be different from year to year and strains circulating one year can be more deadly than those in other years.
- The is estimated to have killed at least 50 million.
- While not as deadly, subsequent flu pandemics, , such as those in 1957, 1968 and 2009 also killed many.
- Even today, according to the WHO, seasonal flu leads to an estimated 3 to 5 million global cases of severe illness with ~250000 to 500000 deaths each year ( ).
- Typically, flu lethality disproportionately affects the very young, the very old and the already ill, the 1918 and 2009 pandemics being exceptions in disproportionately felling those between 20 and 40 years of age.
- Already, apparently the major flu strain circulating in 2017, the influenza A strain H3N2, has led to the headline-grabbing death of an unvaccinated 20 year old mom of two in Arizona ( ).
- Further, seasonal flu is consistently a bigger problem for the older in the US, emerging as the major cause of death among those aged 65 or older, often not directly but as a result of pneumonia from secondary bacterial infections, speculatively an outcome of weakened immune system ( , ).
‘Why are flu and flu shots such a big deal in the US? ‘.
Different countries recommend vaccines for different diseases based on their region-specific disease profiles and economic capability. In the US, vaccine recommendations are made by the(ACIP) which publishes annual flu vaccine recommendations.
Flu vaccines were licensed in the US in 1968 and only began to be included in the pediatric schedule (specifically for those aged 6 to 24 months) in 2004 (). Starting in 2000, ACIP began incrementally increasing its annual vaccination recommendations to include ~84% of the US population by 2009. In 2010, the ACIP expanded its influenza vaccine recommendation further to all US residents >6 months of age ( ), the rationale being the 2009 pandemic H1N1 flu outbreak, where those with greater risk for complications or more severe infections were found to be
- Adults <50 years of age ( ).
- Those with obesity ( , ).
- Specific ethnicities ( , ).
- Postpartum women ( , 13, , ).
Bigger Picture Look on Current Flu Shots: A Sub-optimal Solution to a Real Problem
Push for flu vaccines is predicated on two notions, that they
- Engender milder symptoms compared to those in the unvaccinated.
- Reduce risk of spread to vulnerable groups (the very young, the elderly or already ill), a consequence of herd immunity.
Problem with current flu vaccines is a hit-or-miss situation since their efficacy varies greatly from year to year depending on how well the strains used in the vaccine match those dominating the circulation in a given year (see below from, emphasis mine).
‘The cornerstone of influenza prevention and epidemic control is strain-specific vaccination. Since influenza viruses are subject to continual antigenic changes (“antigenic drift”), vaccine updates are recommended by the WHO each February for the Northern Hemisphere and each September for the Southern Hemisphere. This guidance relies on global viral surveillance data from the previous 5 to 8 months and occurs 6 to 9 months before vaccine deployment. In addition, there are always several closely related strains circulating; therefore, experts must combine antigenic and genetic characterization and modeling to predict which strains are likely to predominate in the coming season.’
See below from 17, emphasis mine.
‘Seasonal influenza outbreaks predictably occur each year and cause an estimated 250,000 to 500,000 annual deaths worldwide (WHO, 2008). Pandemics are highly unpredictable, but pose an even greater threat when they occur. There have been 4 distinct pandemics in the 20th and into the 21st century: 1918, 1957, 1968, and 2009. The worst of these, the 1918 H1N1 influenza pandemic, resulted in 50–100 million deaths globally (WHO, 2014). Despite this substantial disease burden, licensed vaccines provide suboptimal protection against seasonal influenza (typically ranging from 10% to 60%), need to be updated each year, and provide little or no protection against new pandemic influenza strains (CDC, 2017).
A universal flu vaccine that could protect against most seasonal flu strains would be a far better option. However, substantial hurdles range from vaccine design to what represents protective immunity and how to assess it to how to produce such a vaccine.’
Obviously, a universal flu vaccine would be a better solution. Hurdles in the way include figuring out optimal vaccine design, specifically which antigens to include, research on and agreement about the types of immune response that best reflect protection, i.e., correlates of protection, and appropriate methods to produce vaccine such that it retains capacity to mimic as much as possible ability to drive infection-like immunity that is robust and long-standing while still being safe. Greater public support, more funding for flu research and development, better ideas and more creativity, all these are needed to improve this sub-optimal status quo.
1. World Health Organization. “Barriers of influenza vaccination intention and behavior: a systematic review of influenza vaccine hesitancy 2005–2016.” (2016).
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4. Matias, Gonçalo, et al. “Estimates of hospitalization attributable to influenza and RSV in the US during 1997–2009, by age and risk status.” BMC public health 17.1 (2017): 271.
5. Harper, Scott A., et al. “Prevention and control of influenza: recommendations of the Advisory Committee on Immunization Practices (ACIP).” Morbidity and Mortality Weekly Report: Recommendations and Reports 54.8 (2005): 1-41.
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