9 April Episode 127 antibody persistent, risk on reinfection, cross-neutralization, disease and mortality risks

Fri, 04/09/2021 - 12:29

Dear colleagues,

Herewith some interesting papers on antibody persistent, risk on reinfection, cross-neutralization, but also summarizing data on disease and mortality risks.

Ep 127-1 follows a large retrospective cohort of US citizens with known SARS-CoV-2 antibody test (not specified whether anti-S or other) and their likelihood to become PCR (+) and to lose their antibodies over > 90 days: 2.9 million seronegatives and 287,000 seropositives. The results are shown in the figures:  

PCR positivity ratio seropositives/negatives                                        Sero-reversion








As can be seen in the left figure, during the first month, the seropositives are more likely to be PCR (+) (= prolonged shedding), but later on they are less likely, hence (much) lower risk on infection.  

The right figure shows that a significant proportion of the original seropositive subjects lose their antibodies.  Retesting antibodies was only done on less than 10,000 people and the paper does not specify what the risk of reinfection was in those 1,800 who lost their Ab.

Ep 127-2: In Denmark, 500,000 people were followed up, who were tested during the first wave (March-April 2020), with 11,000 PCR(+).  During the second wave (Oct-Dec), those with earlier positive PCR and younger than 65 were 80 % less likely to become  PCR (+) again, while previous infection in those older than 65 protected only 47 % against repeat infection. 

Ep 127-3: Longitudinal serological follow-up in Wuhan (April-Dec) of almost 10,000 individuals. Remarkably stable IgG titers and also neutralizing antibodies (against life virus) over time, but with a significantly decreasing Ab in subjects with an asymptomatic infection.  

Ep 127-4: Degree of cross-neutralization by plasma from first and second wave in South-Africa.  We knew already that plasma of the first wave neutralizes the 501Y.V2 (or South-African) variant poorly (15 fold drop in a life virus test), but here it is shown that plasma from the second wave protects well against first and second wave virus (only 2.3 x difference) and, interestingly, plasma from a person infected with a virus carrying mainly the E484K mutation only, very efficiently neutralized both variants.  Good news for the “next generation vaccine”!!!  


Ep 127-5: a very didactic overview of risk by age: while the infection rate is very similar across age groups, hospitalization risk and death rate increase very spectacularly.










Ep 127-6:  Meta-analysis on thrombo-embolism (TE) in hospitalized COVID: very high prevalence at 20 %, associated with a clear excess in mortality risk: 23 % with TE versus 13 % in non-TE.  

Ep 127-7: A very detailed Nature paper showing that oral cavity is an important site for SARS-CoV-2 infection, with the implication that saliva is a potential route of SARS-CoV-2 transmission.


Ep 127-8: a Science journalist reporting on another Russian COVID vaccine: EpiVacCorona, consists of three synthetic fragments of spike,attached to a carrier protein, which itself is composedof synthetic fragments of the virus nucleocapsidprotein, known as N. The paper contains very little info on scientific data.  Wait and see…


Have a nice WE.