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Tennessee
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Joined: 01/19/2004
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We don't know everything but are definitely learning more.
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BCSnob
Middletown, MD
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Joined: 02/23/2002
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Here is a preprint on a data review from a computerized hospital system which serves approximately 2.5million (25% of the population) in Israel. The review was from March 16 2020 to Jan 27 2021 for reinfection of Covid-19 as defined as a second positive PCR test at least 100 days after the first positive test but excluding patients who may have prolonged shedding of virus (such as immunocompromised patients).
Quote:A total of 149,735 individuals in MHS had a record of a positive PCR test between March 2020 and January 2021. Among them 154 MHS members had two positive PCR tests at least 100 days apart and were included in this study, amounting to 0.1% proportion of reinfection. In this cohort, 73 individuals (47.4%) had symptoms at
both PCR positive events. Members' characteristics are displayed in Table 1.
Age distribution is presented in Figure 1, where the highest count was among individuals aged 10 to 19 years old. The monthly distribution (Figure 2) displayed that the first reinfection (1 member) occurred in July 2020, where the reinfection counts peak in January 2021 (99 members). The distribution of days between first and second positive PCR (Figure 3) shows that 30 individuals were reinfected more than 200 days following their first positive PCR test.
A 1 to 1000 SARS-CoV-2 reinfection proportion in members of a large healthcare provider in Israel: a preliminary report
medRxiv preprint doi: https://doi.org/10.1101/2021.03.06.21253051
They found a 0.1% reinfection rate.
The age group with the largest number of reinfections was 10-19yo
The time frame with the largest number of reinfections was Jan 2021 (when the newer variants were beginning to be dominate)
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BCSnob
Middletown, MD
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Joined: 02/23/2002
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The UK variant (B.1.1.7) has 19 mutations with 8 in the spike protein and one substitution mutation (N501Y) in the RBD (portion of the spike that binds to the Ace2 receptor). The preprint reports that the N501Y substitution in the RBD is responsible for increasing the transmission of this virus variant because it binds tighter to the RBD than the original variant. The report indicates just that one mutation was responsible for higher transmission of the virus; this same mutation is present in the Brazil and South Africa variants.
The N501Y spike substitution enhances SARS-CoV-2 transmission
doi: https://doi.org/10.1101/2021.03.08.434499
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BCSnob
Middletown, MD
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Joined: 02/23/2002
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Covid-19 Vaccines Targeting Multiple Var........nts Are in the Works at Moderna, Novavax
I’ve been waiting to read about this type of approach.
The body produces a range of antibodies which provide some cross reactivity with other viral variants different than the one in the vaccine. If you vaccinate with 3 different viral variants where the antibodies for each give moderate cross reactivity to the other variants the body will produce a broad spectrum of cross reactivity for viral SARS-CoV-2 variants.
One can use computer models to predict all of the possible viral mutations that will binding to the ACE2 receptor and how strongly each bind to ACE2. With the list of mutations that bind strongly one can compute antibody sequences that strongly bind to each and then select the 3-5 theoretical mutations which would produce the most diverse antibodies in the body. these 3-5 theoretical mutations could then be sued to make a multivalent vaccine which provides cross-reactivity to a very broad range of future viral variants (and possibly other corona viruses since they all being to the same ACE2 receptor).
* This post was
edited 03/10/21 11:13am by BCSnob *
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BCSnob
Middletown, MD
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Joined: 02/23/2002
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Here is a preprint on identifying the number of unique antibodies against SARS-CoV-2 produced by memory B cells in previously infected patients (by the original variant). Recall I indicated the body produces a range of antibodies against viruses. This study found 216 unique antibodies that bound to the spike of SARS-CoV-2 (original variant) of which 37 bound the RBD portion of the spike. Of the RBD binding antibodies there were 3 groups based upon the sub regions within the RBD these antibodies recognized. The RBD recognizing antibodies were found to have cross reactivity of varying degrees with the other corona viruses (SARS-CoV-2, MERS, common cold). Further studies found that the mutations in the RBD of the South African variant directly impacted the sub regions of the RBD where the best neutralizing antibodies from the original variant bind. Regeneron sells a treatment for SARS-CoV-2 which is a cocktail of just 2 unique antibodies that bind to the same sub region of the RBD where there is a mutation in the South African variant.
It is these details that will allow researchers to construct a multivalent vaccine that will be effective against all currently circulating SARS-CoV-2 variants, likely future variants, and will likely provide protection against the other corona viruses.
Memory B cell repertoire for recognition of evolving SARS-CoV-2 spike
* This post was
edited 03/11/21 06:59am by BCSnob *
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MEXICOWANDERER
las peñas, michoacan, mexico
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Joined: 06/01/2007
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Any thoughts to an andeno mRNA hybrid serum ?
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BCSnob
Middletown, MD
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Joined: 02/23/2002
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In this study (a preprint of the results) examined the protection afforded by the antibodies produced from the Pfizer vaccine vs a previous Covid infection (original variant) against the new variants. The study found that the antibodies produced by both had lower neutralizing ability against the new variants but the antibodies produced by the Pfizer vaccine saw a smaller loss in protection.
The Pfizer vaccine provided better protection against the new variants than a previous Covid infection.
BNT162b2 mRNA COVID-19 vaccine induces antibodies of broader cross-reactivity than natural infection but recognition of mutant viruses is up to 10-fold reduced
BioRxiv preprint doi: https://doi.org/10.1101/2021.03.13.435222
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BCSnob
Middletown, MD
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Joined: 02/23/2002
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In this preprint I find.....
Quote: In human challenge trials, volunteers are deliberately infected with a pathogen to accelerate vaccine development and answer key scientific questions. In the U.S., preparations for challenge trials with the novel coronavirus are complete, and in the U.K., challenge trials have recently begun.
Characterizing altruistic motivation in potential volunteers for SARS-CoV-2 challenge trials
MedRxiv preprint doi: https://doi.org/10.1101/2021.03.14.21253548
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BCSnob
Middletown, MD
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Joined: 02/23/2002
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Interim data (data analysis before the end of the 2 year clinical trial) from the AstraZeneca phase 3 clinical trial (2 doses) in South Africa indicated has 10% effectiveness at preventing mild to moderate infections by the South Africa variant.
Quote:Among the 42 participants with Covid-19, 39 cases (92.9%) were caused by the B.1.351 variant; vaccine efficacy against this variant, analyzed as a secondary end point, was 10.4% (95% CI, ?76.8 to 54.8).
Efficacy of the ChAdOx1 nCoV-19 Covid-19 Vaccine against the B.1.351 Variant
New Eng Journal of Med
There were no severe cases of covid or deaths due to the South African variant in either the placebo or vaccinated participants; therefore, the effectiveness of this vaccine to prevent hospitalization or death due to the South African variant could not be determined.
* This post was
edited 03/17/21 11:13am by BCSnob *
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MEXICOWANDERER
las peñas, michoacan, mexico
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Looks like the mRNA based serums win hands down.
How likely is it the pathogen will continue to mutate with say an infection rate of say 10% of what is was throughout 2020 ?
Is it linear?
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