Flu pandemics recur reliably but unpredictably every decade or so, and their extent and intensity vary. With COVID-19, we may be in midst of a once-every-50-years event, perhaps similar to 1957 pandemic, but not as bad as the 1918 pandemic.
Let’s talk about the 1957 pandemic.
Pandemics result from the emergence of viral strains that are novel, often from genetic recombination in animal reservoirs. The 1957 pandemic was due to influenza A (H2N2). https://cdc.gov/flu/about/viruses/types.htm… “Serological archeology” suggests it resembled 1889 strain. https://ncbi.nlm.nih.gov/pubmed/8877331
The virus that caused the 1957 pandemic is different from the coronavirus causing COVID19. Both are rhinoviruses, but from different phyla. https://statnews.com/2020/03/03/who-coronavirus-different-than-influenza-can-be-contained/… Despite the different pathogens, we can still understand what is happening by studying past pandemics.
First, here is a timeline via the CDC of the history of public health responses to flu pandemics: https://www.cdc.gov/flu/pandemic-resources/pandemic-timeline-1930-and-beyond.htm
Best estimate at present is COVID-19 has intermediate transmissibility compared to other pandemics (an effective reproductive rate of 2-4 new cases per old case) and intermediate mortality (0.5%-2.0%, though still unclear).
A classic 1961 paper analyzing the 1957 pandemic https://ncbi.nlm.nih.gov/pubmed/13758900 concluded that the disease likely started in central China (like COVID-19) and became known to the rest of the world in April of 1957. Pandemics have started on many continents.
Globally, the 1957 pandemic killed 1.1M people. There was regional variation; for instance: 0.3 deaths/10,000 in Egypt and 9.8/10,000 in Chile. GDP and latitude explained 43% of the variance in excess mortality. https://t.co/vUZQfTez3X?amp=1
Mortality in the 1957 global flu pandemic was U-shaped, with the very young and very old dying (https://ncbi.nlm.nih.gov/pubmed/8877331). This is typical, but this appears NOT to be the case with COVID-19, where the young are spared.
The first wide awareness of the 1957 pandemic in the USA was a tiny article on April 17, 1957 in the New York Times on page 3 noting that 250,000 people were afflicted in Hong Kong (or 10% of the population). The 1957 pandemic was first recognized in USA in June in RI, but other outbreaks soon occurred in CA. By September, it was everywhere. And it recurred when schools re-opened in fall of 1957. A first peak in excess death was in October, and a second peak in February of 1958
Peaks in epidemics have to do with pathogen flows across networks; other social factors (like changes in population mixing across time, or school re-openings); weather; etc. As a note, the flu has a baseline seasonality.
Paul Plante says
This subject of viruses, which are found in nature, is really quite fascinating.
In Chapter 41, “Structure and Classification of Viruses,” Medical Microbiology, 4th edition, by Hans R. Gelderblom, we learn as follows about viruses, to wit:
Viruses are small obligate intracellular parasites, which by definition contain either a RNA or DNA genome surrounded by a protective, virus-coded protein coat.
Viruses may be viewed as mobile genetic elements, most probably of cellular origin and characterized by a long co-evolution of virus and host.
For propagation viruses depend on specialized host cells supplying the complex metabolic and biosynthetic machinery of eukaryotic or prokaryotic cells.
A complete virus particle is called a virion.
The main function of the virion is to deliver its DNA or RNA genome into the host cell so that the genome can be expressed (transcribed and translated) by the host cell.
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So one could well say that the virus was an alien intelligence.
As to the viruses that infect humans, they are currently grouped into 21 families.
As to the corona virus, which is an RNA virus, as opposed to a DNA virus, we have this:
RNA viruses, comprising 70% of all viruses, vary remarkably in genome structure.
Because of the error rate of the enzymes involved in RNA replication, these viruses usually show much higher mutation rates than do the DNA viruses.
Mutation rates of 10-4 lead to the continuous generation of virus variants which show great adaptability to new hosts.
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That is what medical professionals and public health professionals know about these viruses, and have known for some long time now, even if these idiot politicians who have taken over from the real professionals who should be speaking instead of the idiots are clueless and as a result, are whipping up all sorts of hysteria and fear over something “novel” like COVID-19.
As to “killing” viruses, as the scared and hysterical out-of-their-league idiot politicians are promising to do, we have this to consider:
Strictly speaking, viruses can’t die, for the simple reason that they aren’t alive in the first place.
Although they contain genetic instructions in the form of DNA (or the related molecule, RNA), viruses can’t thrive independently.
Instead, they must invade a host organism and hijack its genetic instructions.
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As to the subject of previous pandemics, from Chapter 43, “Viral Genetics,” of Medical Microbiology, 4th edition, this chapter by W. Robert Fleischmann, Jr., we have as follows:
Recombination by Independent Assortment
Independent assortment occurs when viruses that have multipartite (segmented) genomes trade segments during replication.
These genes are unlinked and assort at random.
Independent assortment between an animal and a human strain of influenza virus (see Ch. 58) during a mixed infection can yield an antigenically novel influenza virus strain capable of infecting humans but carrying animal-strain hemagglutinin and/or neuraminidase surface molecules.
This recombinant can infect individuals that are immune to the parent human virus.
This mechanism results in an immediate, major antigenic change and is called antigenic shift.
Antigenic shifts in influenza virus antigens can give rise to pandemics (worldwide epidemics) of influenza.
Such antigenic shifts have occurred relatively frequently during recent history.
Because the number of different serotypes of hemagglutinin and neuraminidase are limited, a given strain reappears from time to time.
For example, the H1N1 influenza virus strain was responsible for the 1918 to 1919 influenza pandemic that caused 20 million deaths.
The same virus also caused pandemics in 1934 and in 1947, then disappeared after 1958 and reappeared in 1977.
The reappearance of virus strains after an absence is believed to be the result of recombinational events involving the independent assortment of genes from two variant viruses.
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That is what public health professionals know, which is why back in the past, when it was still RULE OF LAW as opposed to RULE OF ******* IDIOT HACK POLITICIANS which we now have, the people of the Commonwealth of Virginia through their elected representatives enacted Title 32.1 of the Code of Virginia, titled Chapter 2. Disease Prevention and Control, which Chapter contains § 32.1-35. List and reports of diseases and dangerous microbes and pathogens, which states as follows:
The Board (Virginia Board of Health, not Ralph Northam) shall promulgate from time to time a list of diseases, including diseases caused by exposure to any toxic substance as defined in § 32.1-239 and including diseases that may be caused by exposure to an agent or substance that has the potential for use as a weapon, that shall be required to be reported.
The Board shall also promulgate from time to time a list of dangerous microbes and pathogens that shall be required to be reported by laboratories.
The Board may classify such diseases, microbes and pathogens and prescribe the manner and time of such reporting.
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Has any of that been done?
Is there even a functioning Board of Health in the Commonwealth of Virginia?
Does anyone even have a clue.