COVID-19
Herd Immunity Re-Revisited
6. How should we act?
The World Health Organization (WHO) has not changed its policy on COVID-19: they still call for testing and contact tracing. If someone is infected with COVID-19, this person should be isolated until cured. All contacts should be identified and informed. Participate in contact tracing to help stop the spread of the virus. Contacts should be quarantined and/or tested. We are all safer when COVID-19 is stopped.
6.1 Zero is impossible?
An often-heard argument is that it is impossible to reduce the number of SARS-2 infections to zero. I guess this is true for many undesired parameters like traffic accidents, murders and suicides, sexual assault and rapes, and tuberculosis infections. But this does not imply we take no precautions against these, in contrary we repress these in the Western world, even though we sometimes should perform better. We have speed limits and traffic regulations, gun regulations, codes of conduct. And we’ve introduced test, trace & isolate to reduce a once high frequent endemic disease in Europe to a very low frequency, near zero, without major impact on society. Since it was already done for tuberculosis. As my father says, “Cannot do it is buried, will not do it lies next to it”. Europe should learn from East-Asia and try to reduce COVID-19 infections.
6.2. Swing low
In contrast to the failed herd immunity strategies, Europe has not seriously tried to minimize infections. In Europe lockdowns were never used to eliminate the virus, and they might not be required. Various methods exist to avoid contamination, like personal protection by distance, facemasks, and ventilation with filtering. Isolating cases is the default strategy for any epidemic, and results in maximum effect at low costs. So how can we identify cases to isolate?
6.3. Symptoms cannot be used as testing
Symptoms are only a poor indication of being infected, asymptomatic or presymptomatic people have the highest virus titers. Early in the epidemic it was shown that asymptomatic people can spread the virus. Coughing and sneezing is not required to spread the virus, since virus-carrying aerosols are also formed during normal breathing and talking.
Vaccinated people are more protected against disease but are still very likely to become infected. They might even be more likely to become asymptomatic virus spreaders.
Moreover, mild SARS-2 symptoms are very general. Similar symptoms are observed in people with cold or flu, respiratory allergies, or pollution-irritated airways. With both high frequencies of false-negatives and false-positives, symptoms fail as a suitable test to detect SARS-2 infection. This is also valid in a tiered approach, like symptomatic people should be tested.
Vaccinated people are more protected against disease but are still very likely to become infected. They might even be more likely to become asymptomatic virus spreaders.
Moreover, mild SARS-2 symptoms are very general. Similar symptoms are observed in people with cold or flu, respiratory allergies, or pollution-irritated airways. With both high frequencies of false-negatives and false-positives, symptoms fail as a suitable test to detect SARS-2 infection. This is also valid in a tiered approach, like symptomatic people should be tested.
6.4. Test for virus, not disease
The safe sex campaign was not about being careful about sexual contacts with people having full-blown AIDS, but to avoid having unprotected sex with someone infected. Everyone knew that the virus could spread before disease occurred.
Being contagious is not a disease state. Medical diagnosis is not the same as the epidemiological state of having a virus. High virus loads in the nose or throat makes someone contagious. Breathing out produces aerosols that could contaminate and infect others. Presymptomatic and asymptomatic people are often most contagious as indicated by SARS-2 virus load and do not need symptoms to contaminate other people. SARS-2 virus in the lungs and circulation causes pneumonia and life-threating COVID-19, respectively. Please note that both the lungs and circulation are not sampled during routine testing.
Being contagious is not a disease state. Medical diagnosis is not the same as the epidemiological state of having a virus. High virus loads in the nose or throat makes someone contagious. Breathing out produces aerosols that could contaminate and infect others. Presymptomatic and asymptomatic people are often most contagious as indicated by SARS-2 virus load and do not need symptoms to contaminate other people. SARS-2 virus in the lungs and circulation causes pneumonia and life-threating COVID-19, respectively. Please note that both the lungs and circulation are not sampled during routine testing.
6.5 Practice of testing
Testing is the best way to detect the virus infections. In general, infection is monitored by sampling in the mouth and nose and subsequent detected by either RT-PCR for SARS-2 RNA or by an antigen test to detect SARS-2 nucleocapsid protein. Please note that the current European vaccines only contain the Spike protein or its mRNA, and thus will not be detected in a test for the nucleocapsid.
Virus titers can rapidly rise early in disease; virologists are not surprised by a million-fold rise between two consecutive days. Self-tests detecting the antigen are less sensitive than RT-PCR but quite reliable. Repeated testing, preferably daily, is the most sensitive method in practice. Any test can be false negative or false positive, but repeated positive results are strong indication of true positives. Repeated tests, even of limited sensitivity like antigen tests, are invaluable to detect contagious people.
Virus titers can rapidly rise early in disease; virologists are not surprised by a million-fold rise between two consecutive days. Self-tests detecting the antigen are less sensitive than RT-PCR but quite reliable. Repeated testing, preferably daily, is the most sensitive method in practice. Any test can be false negative or false positive, but repeated positive results are strong indication of true positives. Repeated tests, even of limited sensitivity like antigen tests, are invaluable to detect contagious people.
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John. J.L. Jacobs. 18.02.2022
