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BREAKING NEWS
Source: COVID-19 Breaking News  Aug 18, 2020  1 month ago
COVID-19 Breaking News! French Study Confirms Previous Coronavirus Immunity Offers No Protection Against SARS-CoV-2
COVID-19 Breaking News! French Study Confirms Previous Coronavirus Immunity Offers No Protection Against SARS-CoV-2
Source: COVID-19 Breaking News  Aug 18, 2020  1 month ago
COVID-19 Breaking News: A new study by researchers from Institut Pasteur-Paris, Sorbonne Université-Paris, Service de Médecine-Paris, and  Genalyte Inc -California confirms  that having previous immunity against common coronaviruses (alpha and beta) cannot protect against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).


 
The news study contradicts many previous studies that claimed various segments of the populations were protected as a result of past human coronavirus infections without providing proper supporting evidence.
 
The research findings were published on a preprint server and are currently being peer-reviewed for publication a journal. https://www.medrxiv.org/content/10.1101/2020.08.14.20173393v1
 
The novel coronavirus, SARS-CoV-2 has shown a varied level of genetic heterogeneity and disease severity worldwide. The virus has also been shown to severely affect older adults and people with comorbidities, leaving healthy children and young adults in a relatively safer position.
 
Considering these differential viral responses, it was generally hypothesized that having a previous history of infection or immunization against common alpha coronaviruses (HCoV-NL-63 and -229-E) and beta coronaviruses (HCoV-OC-43 and -HK-U1) may provide cross-protection against SARS-CoV-2.
 
However this study dispels all such assumptions and confirms that no previous immunity generated from past coronavirus infections offers any level or protection against the SARS-CoV-2 virus.
 
The study team analyzed serum samples collected from 76 healthy individuals before the outbreak of COVID-19.
 
Significantly, the scientists found that only about 8% of serum samples have cross-reactivity against several SARS-CoV-2 antigens, including S2 domain, full-length spike protein, nucleocapsid.
 
More importantly however, no cross-reactivity against receptor binding domains (RBDs) of the viral spike protein was observed.
 
Furthermore, these serum samples showed random cross-reactivity against all types of common coronaviruses.
 
Based on these observations, the scientists concluded that immunity developed in the pre-COVID era show only nonspecific reactivity to SARS-CoV-2 antigens.
 
The study team for further verification checked the reactivity of therapeutic intravenous immunoglobulin G (IgG) formulations, which were manufactured before the COVID-19 pandemic. These intravenous formulations, which are composed of IgG molecules isolated from 10,000 pooled plasma samples of healthy individuals, are expected to provide valuable information about pre-existing adaptive immune response of the general population.
 
Utilizing three different sets of intravenous formulations, the scientists observed significantly high IgG reactivity against all types of common coronaviruses and detectable IgG reactivity against different SARS-CoV-2 antigens, including full-length spike protein and S2 domain. However, no reactivity against nucleocapsid was observed.
 
Based on these observations, the study team concluded that the ada ptive immunity developed before COVID-19 pandemic commonly shows cross-reactivity against SARS-CoV-2 antigens in the general population.
 
To further determine whether antibodies developed against SARS-CoV-2 can react to both SARS-CoV-2 and common coronavirus antigens, the study team analyzed IgG reactivity of serum samples collected from eight severely affected COVID-19 patients against antigens of both SARS-CoV-2 and common coronaviruses.
 
The study team observed an increase in antibody titers (IgG) against SARS-CoV-2 and beta coronavirus antigens. Because the patients tested positive only for SARS-CoV-2 and not for other coronaviruses, the scientists believed that these IgG responses against beta coronavirus are possibly a result of cross-reactivity.
 
The researchers also observed that early serum samples collected from patients were reactive to beta coronavirus; also, serum samples of two patients were reactive to alpha coronavirus. All these immune responses occurred even before the appearance of antibodies against SARS-CoV-2. From these observations, the scientists believed that developing immunity against common coronavirus infection cannot protect individuals from developing COVID-19.
 
Their conformations was further verified by a series of in vitro assays showing that pre-COVID serum samples without detectable levels of anti-RBD antibodies failed to neutralize SARS-CoV-2. Similarly, intravenous IgG formulations prepared before the SARS-CoV-2 pandemic did not show any neutralizing effects.
 
The study team also concluded based on the research findings that although cross-reactivity happens between SARS-CoV-2 and common coronaviruses, cross-protection against SARS-CoV-2 can be achieved only from antibodies developed against SARS-CoV-2.
 
It was observed that lack of cross-protection may be due to not having structural similarity between RBDs of SARS-CoV-2 and common coronaviruses. Structural homology between the S2 domains of SARS-CoV-2 and common coronaviruses is responsible for cross-reactivity, but fails to provide cross-protection.
 
Significantly another important observation made by the study team is that intravenous IgG formulations developed before the SARS-CoV-2 pandemic do not hamper the neutralizing ability of patient-derived serum IgG against SARS-CoV-2.
 
This finding indicates that individuals who have recovered from SARS-CoV-2 infection should not be excluded as donors for preparing intravenous IgG formulation during the COVID-19 pandemic.
 
The study team however warns that the crucial thing to be taken into consideration is that serum IgG samples from these donors should not amplify the infection instead of nullifying it (antibody-dependent SARS-CoV-2 enhancement activity).
 
As it is still not properly established whether plasma samples obtained from people recovered from COVID-19 are effective in treating SARS-CoV-2 infected patients,( a recent Mayo Study findings were totally dubious as there were no control groups https://www.thailandmedical.news/news/covid-19-warning-media-reports-on-success-of--studies-on-plasma-therapy-in-america-unreliable-and-misleading,-no-control-groups-etc) the scientists believed that intravenous IgG formulations developed during the COVID-19 pandemic are not supposed to play any therapeutic roles.
 
They could however have prophylactic effects against SARS-CoV-2 infection.
 
For more COVID-19 Breaking News, keep on logging to Thailand Medical News.

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