Covid-19 and the Herd Effect

by Jack

On Mar 15th, Governor Gavin Newsom said 56 percent of California’s population, a whopping 25.5 million people, would be infected over an eight-week period.  As of April 9th, we are no where near that dire predication.

We have a mere 19,691 cases of covid-19 when we should have close to a million.  So, how did our experts miss the actual rate of infection by such wide margins?  The answer may be from a phenomena called herd immunity.   See below:

Herd immunity (also called herd effect, community immunity, population immunity, or social immunity) is a form of indirect protection from infectious disease that occurs when a large percentage of a population has become immune to an infection, whether through previous infections or vaccination, thereby providing a measure of protection for individuals who are not immune. In a population in which a large proportion of individuals possess immunity, such people being unlikely to contribute to disease transmission.

We lack the testing data to know for sure what is taking place, but it seems very possible that CA may have had the Covid-19 virus circulating around the state long before China made the declaration of a problem.  This has created a population with antibodies.   Also contributing to limiting the spread is California’s fair weather.  Flu peaks during cold winter months and recedes during warm summer months. Whatever the reason may for our low statistics CA is certainly getting a break, unlike New York.

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7 Responses to Covid-19 and the Herd Effect

  1. Harold says:

    Info taken from the internet about testing you might find useful. I would suggest you might want to do more research.

    (I have felt that the results of any of these current test are only as accurate at the moment they are taken. After that point in time you may touch or be exposed to droplets from a unmasked individual)

    The most common test is a molecular test, and how does it work?
    Molecular tests were the first type of test for COVID-19, used by both the World Health Organization (WHO) and the Center for Disease Control and Prevention (CDC).

    Most recently, Abbott Laboratories announced a point-of-care molecular test that can deliver results in as little as 5 minutes.
    (A new novel coronavirus test may make diagnosing COVID-19 as easy as the flu. The new point-of-care test, having just received an emergency-use authorization by the U.S. Food and Drug Administration (FDA), will be able to deliver results in as little as five minutes, according to the manufacturer. This test from medical device company Abbott, which begins shipping April 1, may soon be available at your local urgent care clinic.)

    “This is going to be the fastest molecular point-of-care test to date,” said John Frels, Ph.D., Abbott’s vice president of research and development, in an interview with ABC News. “It generates a positive result in 5 minutes and negative results in 13 minutes.”

    How is the molecular test administered?
    Molecular tests typically involve inserting a swab into the back of the nasal passage through one nostril and rotating the swab several times for 15 seconds. This process is then repeated through the other nostril. With the introduction of portable/point-of-care testing, these tests can even be done entirely in the provider offices or even the parking lot of a drive-thru testing site.

    What’s the science behind it?
    In a patient with a COVID-19 infection, genetic material from SARS-CoV-2, the virus that causes COVID-19, is generally detectable in upper and lower respiratory specimens.
    In acute respiratory infections, molecular tests are routinely used to detect the presence of viral genetic material in a sample.

    How long does it take to get results?
    Most RT-PCR tests can take anywhere from a few hours to a few days, but new rapid diagnostic tests for COVID-19 show promise of results in less than an hour. Examples of rapid diagnostic tests that have been recently authorized include those by:
    • Abbott: results in as little as 5 minutes
    • Mesa Biotech: results in as little as 30 minutes
    • Cepheid: results in as little as 45 minutes

    How accurate are molecular tests?
    If the test results come back positive, it is very likely that you have a COVID-19 infection. However, there’s a small chance that it could be a false positive, meaning that the test is positive, but you actually don’t have a COVID-19 infection.
    If the test results come back negative, it means that the virus that causes COVID-19 was not found in the sample above the limit of detection. A false negative is possible, and should be considered in combination with your symptoms, travel history, and other possible ways of having been exposed.

    What is the serological test, and how does it work?
    Serological tests are now being developed and can help give us a broader picture of COVID-19 infection spread. Unlike molecular tests, serological tests can identify those that were infected and have recovered.
    The CDC is evaluating two serological tests that they’ve developed, and over 40 manufacturers have notified FDA that they have validated and are offering serological tests.

    How is the serological test administered?
    Serological tests rely on detecting antibodies in a blood sample, usually obtained through a simple finger prick. These tests do not require special equipment to process the results, which allows them to be used in laboratories or at point-of-care.
    What’s the science behind it?
    When you’re exposed to the virus, your body develops antibodies, which can take several days to over a week. Antibodies are proteins your body makes when mounting a response against invading germs.
    The presence of immunoglobulin M (IgM) antibodies indicate recent exposure to COVID-19, while the presence of immunoglobulin G (IgG) antibodies indicate later-stage infection. The rapid response serological tests typically use a technique called enzyme-linked immunological assay (ELISA), which detects the presence of these antibodies to the virus.

    How long does it take to get results?
    Serological tests are typically much faster than standard molecular tests, returning results in as few as 10 to 15 minutes.

    What exactly does the serological test tell you?
    Since it can take several days for the body to develop an antibody response to the virus, serological tests may not be useful in identifying a current infection alone. They have the potential of producing a false negative, a false result when you actually have the infection.
    However, they can identify individuals who have had the infection and have recovered, suggesting that those people are now immune to the virus. It is still unclear how long any immunity lasts and if reinfection is possible.

    How accurate are serological tests?
    Serological test development is allowed under current FDA policy, but until recently, the FDA wasn’t authorizing them like they do molecular tests.
    • Negative results do not rule out SARS-CoV-2 infection, particularly in those who have been in contact with the virus. Follow-up testing with a molecular diagnostic should be considered to rule out infection in those individuals.
    • Results from antibody testing should not be used as the sole basis to diagnose or exclude SARS-CoV-2 infection or to inform infection status.

    • Positive results may be due to past or present infection with non-SARS-CoV-2 coronavirus strains, such as coronavirus HKU1, NL63, OC43, or 229E.
    As of April 1, the FDA issued its first approval for a serological test by Cellex, whose test delivers results in about 15 minutes. Previously, Bodysphere announced the approval of a 2 minute serological test, but they later clarified as the test was not actually approved.

    Are any tests approved for at-home testing?
    Currently, at-home testing is not covered under FDA policy, and no tests have been authorized. Several companies, including Everlywell and Nurx, had begun to sell at-home COVID-19 tests. However, many of these companies stopped selling these tests after the FDA issued a statement warning consumers that the tests were unauthorized.
    PLEASE NOTE: There is little information on the accuracy of at-home testing, but results from a study led by the UnitedHealth Group seem promising. It suggests that results from self-collected testing were similar in accuracy to provider-collected testing. You should read more about at-home testing

    Who should be tested for COVID-19?
    Ultimately, decisions about testing are at the discretion of state and local health departments and/or individual clinicians. If you have symptoms of COVID-19 but don’t need immediate medical attention, call your medical provider to determine if you need testing.

    The bottom line
    If you have an active COVID-19 infection, the molecular test will generally be more accurate unless you’ve started developing antibodies to the virus. The serological test will be able to tell you if you’ve had the infection and recovered (regardless of having symptoms or not). This can be useful in determining who may be able to go back to work or school. Rapid response, point-of-care tests and at-home tests are also being developed.
    – – –

  2. Harold says:

    Here is another news article that is something to consider about Covid-19 reinfecting people who had the disease and recovered from it. Seems, immunity may not be certain after recovery and relapse a possibility. So it would be best if you continue to practice CDC recommendations and use common sense following a recovery.

    Right now so much is uncertain about how this virus lives on, but world governments are working on it, and hopefully sharing their findings. I read where China (hey, I know) found a protein that may be susceptible to a prior vaccine. We will see.

    We will conquer this thing.

    https://currently.att.yahoo.com/news/recovered-coronavirus-patients-test-positive-161747233.html

  3. Post Scripts says:

    Thanks for all your input. Hoping everyone has a Happy Easter.

  4. Harold says:

    There are still A$$Holes in the world at large. This one should be infected and quarantined to see if he can make it without any medical assistance.

    https://currently.att.yahoo.com/autos/york-nurses-lauded-virus-efforts-153700970.html

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