Re: Covid-19: Past infection provides 83% protection for five months but may not stop transmission, study finds
What is the definition of protection? We know that immune response (not necessarily viral damage) often causes headaches, myalgia, and fatigue, (even chills/fever). Even mRNA vaccines (which only involve the Spike protein and no other viral aspect) can stimulate the immune response and present these symptoms.
So, how are "symptomatic" cases defined? Symptoms that are unique to viral damage like sore throat, congestion, cough, etc? Or do we include a short period of symptoms that are solely immune response?
Also, do we count asymptomatic infections as protective or non-protective? And what Ct is used to define "infection"? How are high Ct that are borderline negative and essentially non-shedding categorized? Should Ct be "banded" into categories of "strongly shedding", "moderately shedding", "borderline positive / lightly shedding", "negative" based on Ct counts so these categories could be used to identify PCR "positive-ness"?
I would propose that a number like 83% is meaningless unless a clear definition of what the 83% represents is clearly specified. Below we can see that only 15 of the 44 were symptomatic.
Also, serious cases such as admission to a hospital should be categorized.
"The researchers detected 44 potential reinfections in the positive cohort, 15 (34%) of which were symptomatic. Some 42 were defined as possible (two positive PCR samples 90 or more days apart, or a new PCR positive at least four weeks after an antibody positive result), and two were defined as probable (additionally required quantitative serological data or supportive viral genomic data)"
How much immunity does Covid 19 infection give?
That depends upon how "immunity" is specifically defined.
Competing interests: No competing interests