Its A Little Late For This News To Be Helpful For This Years Halloween, But Perhaps For Next Y BEST
LINK >>>>> https://urlin.us/2trFtD
Its A Little Late For This News To Be Helpful For This Years Halloween, But Perhaps For Next Y
The reason experts are particularly concerned about the flu this year is that many people, especially very young children, may have little or no immunity against the respiratory infection because the masking, social distancing and other behaviors aimed at protecting against COVID have blunted flu's spread, too. Also, the CDC notes, young children would do well to get a flu shot soon because they require two shots one month apart, and it takes time to build up immunity.
Yet the world is vulnerable to the next pandemic, perhaps even more than in 1918, when the pace and frequency of global travel was considerably less than today. As the contributors to this chapter demonstrate, there is still much to be learned from past pandemics that can strengthen defenses against future threats. The chapter begins with a review of the events of 1918, the lessons they offer, and the historical and scientific questions they raise. It describes the epidemiology and symptomology of that deadly viral strain, limited efforts toward prevention and treatment, and the resulting social disruption and its exacerbation by the actions of public officials and the media.
Three extensive outbreaks of influenza within 1 year is unusual, and may point to unique features of the 1918 virus that could be revealed in its sequence. Interpandemic influenza outbreaks generally occur in a single annual wave in the late winter. The severity of annual outbreaks is affected by antigenic drift, with an antigenically modified virus strain emerging every 2 to 3 years. Even in pandemic influenza, while the normal late winter seasonality may be violated, the successive occurrence of distinct waves within a year is unusual. The 1890 pandemic began in the late spring of 1889 and took several months to spread throughout the world, peaking in northern Europe and the United States late in 1889 or early 1890. The second wave peaked in spring 1891 (over a year after the first wave) and the third wave in early 1892 (Jordan, 1927). As in 1918, subsequent waves seemed to produce more severe illness so that the peak mortality was reached in the third wave of the pandemic. The three waves, however, were spread over more than 3 years, in contrast to less than 1 year in 1918. It is unclear what gave the 1918 virus this unusual ability to generate repeated waves of illness. Perhaps the surface proteins of the virus drifted more rapidly than other influenza virus strains, or perhaps the virus had an unusually effective mechanism for evading the human immune system.
One theory that may explain these data concerns the possibility that the virus had an intrinsically high virulence that was only tempered in those patients who had been born before 1889. It can be speculated that the virus circulating prior to 1889 was an H1-like virus strain that provided partial protection against the 1918 virus strain (Ministry of Health, 1960; Simonsen et al., 1998; Taubenberger et al., 2001). Short of this cross-protection in patients older than 29 years of age, the pandemic of 1918 might have been even more devastating (Zamarin and Palese, 2004). A second possibility remains that the high mortality of young adults in the 20 to 40 age group may have been a consequence of immune enhancement in this age group. Currently, however, the absence of pre-1918 human influenza samples and the lack of pre-1918 sera samples for analysis makes it impossible to test this hypothesis.
The sequence of the 1918 HA is most closely related to that of the A/ swine/Iowa/30 virus. However, despite this similarity the sequence has many avian features. Of the 41 amino acids that have been shown to be targets of the immune system and subject to antigenic drift pressure in humans, 37 match the avian sequence consensus, suggesting there was little immunologic pressure on the HA protein before the fall of 1918 (Reid et al., 1999). Anothe