So what's the big deal about respiratory infections? The scope of the problem is actually gigantic.

In the US, in 2001, approximately 500 million non-influenza-related viral respiratory tract infections episodes occur per year. Similarly, if the treatment patterns reported by the respondents are extended to the population, the total economic impact of non-influenza-related VRTI approaches $40 billion annually.

(The economic burden of non-influenza-related viral respiratory tract infection in the United States. Fendrick AM1, Monto AS, Nightengale B, Sarnes M. Arch Intern Med. 2003 Feb 24;163(4):487-94.)

As for influenza, the story is much worse.

2007 - An average of 36,000 deaths and over 200,000 hospitalizations associated with influenza occur each year in the United States. The overall national economic burden of influenza-attributable illness for adults, age 18 years and above is $83.3 billion.

(Thompson WW, Shay DK, Weintraub E, et al. Mortality associated with ininfluenzaenza and respiratory syncytial virus in the United States. JAMA. 2003; 289:179-186 Ininfluenzaenza-associated hospitalizations in the United States. JAMA. 2004; 292:1333-1340.Molinari NA, Ortega-Sanchez IR, Messonnier ML, Thompson WW, Wortley PM, Weintraub E, Bridges CB. The annual impact of seasonal ininfluenzaenza in the US: measuring disease burden and costs. Vaccine. 2007; 25(27):5086-96. Epub 2007 Apr 20.)

In 1997, it was estimated that the cost to employers of patients with respiratory infections in the United States was $112 billion, including costs of medical treatment and time lost from work.

(Economic Burden of Respiratory Infections in an Employed Population. Howard G. Birnbaum, PhD; Melissa Morley, MA; Paul E. Greenberg, MS, MA;and Gene L. Colice, MD, FCCP)

A research team led by the US Centers for Disease Control and Prevention (CDC) has estimated the global death toll from the 2009 H1N1 swine flu pandemic at more than 284,000. The team estimated that 80% of those who died were younger than 65, which is in accord with previous observations that the pandemic H1N1 burden fell heavily on younger people, unlike the pattern for seasonal flu. The WHO estimates that 250,000 to 500,000 people (0.004% to 0.008% of the population) die of seasonal flu annually, and flu deaths in past pandemics ranged from 0.03% of the population in 1968 to 1% to 3% in 1918.

(Dawood FS, Iuliano AD, Reed C, et al. Estimated global mortality associated with the first 12 months of 2009 pandemic influenza A H1N1 virus circulation: a modelling study. Lancet Infect Dis 2012 Jun 26)

There are new strains of contagious respiratory viruses being encountered almost every year. 2014 saw the emergence of Enterovirus D-68 in the US. SARS and MERS remain possible threats, and there is concern that the avian or bird flu could mutate to be transmissible between humans.

A 2008 internal report prepared by the World Bank estimated that a severe influenza pandemic could kill 71 million people and cause a recession costing more than $3 trillion. Some experts have estimated a death toll ranging from 180 million to 250 million in a severe pandemic. The World Bank report said that sagging tourism, transportation, retail sales, and productivity, coupled with worker absenteeism, could reduce global gross domestic product (GDP) by 4.8%. It was estimated that a "mild" pandemic, similar to the Hong Kong flu of 1968-69, could kill 1.4 million people and reduce global GDP by 0.7% in the first year. The projection for a "moderate" pandemic like that of the Asian flu in 1957-58 is that it could cause 14.2 million deaths and reduce global economic activity by 2%.

(Provided by the Center for Infectious Disease Research and Policy (CIDRAP), University of Minnesota. 2002-2008 Regents of the University of Minnesota.)
"Respiratory disease is the second most common illness responsible for emergency admission to hospital. There are an estimated one million admissions a year for respiratory disease in the UK suggests at a cost of 1,496.4 million to secondary care. In 2002/2003 nearly 25 million certified sickness absence days related to respiratory disease (not including days lost from self-certified illness). This amounts to an estimated 1,728.5 million of lost production due to respiratory disease."
British Thoracic Society (2006) - Burden of Lung Disease 2nd Edition

An Australian study in 2003 found that the mean cost of acute respiratory illnesses among preschoolers was $309. Influenza illnesses had a mean cost of $904, compared with RSV, $304.

(The Cost of Community-managed Viral Respiratory Illnesses in a Cohort of Healthy Preschool-aged Children 06/09/2008. Stephen B. Lambert; Kelly M. Allen; Robert C. Carter; Terence M. Nolan)

For 2003,the total annual cost of respiratory infection of young children in Germany was estimated to be $213 million.

(Ehlken, B., G. Ihorst, B. Lippert, A. Rohwedder, G. Petersen, M. Schumacher, and J. Forster. 2005. Economic impact of community-acquired and nosocomial lower respiratory tract infections in young children in Germany. Eur. J. Pediatr.)

Respiratory illness alone cost as much as $134 per employee per year in 2004.

(Health, Absence, Disability and Presenteeism Cost Estimates of Certain Physical and Mental Health Conditions Affecting U.S. Employees. J Occupy Evviron Med. 2004;46:398-412 Goetzel RZ)

Tuberculosis is the most prevalent respiratory infection in the world, with nearly a third of the worlds total population being currently infected with this organism. TB is caught just like the flu or the common cold, by breathing in the infected aerosolized droplets that are emitted especially when an infected person coughs. According to the World Health Organization, someone is infected every second. An untreated infectious person is estimated to infect 10 to 15 persons per year. The WHO declared TB to be a global emergency, and estimates that 9.2 million new cases of TB occurred in 2006, and around 1.6 million deaths were caused by the disease. While TB has long been considered curable, it is becoming less so with cases of resistant organisms ever increasing. Treatment of a singe case of resistant TB is estimated to cost $250,000 in the US, and may prove ineffective. In 2006, WHO launched the new Global Plan to Stop TB 2006-2015, at the cost of $56 billion, to attempt to save some 14 million lives over the following 10 years. The further and ultimate hope is to eliminate TB as a major public health issue by 2050

Source World Health Organization Website