02-21-2021, 06:18 PM
NBCNews article Feb 7, 2021
CDC page on COVID reinfection (as typical, says nothing).
NYPost article Feb 1, 2021 reporting on a as-yet-unreviewed Jan 29 paper.
From the Jan 29. report:
To me, the big numbers are the 6.2 cases per person-year for the people never infected and the 1.1 cases per person year for the previously infected. If those hold up, then in the situation these people are in, they will get an infection every year. (That depends partly on the frequency of exposure, which depends on the number of people with active infections. So, that 1.1 should drop as we approach herd immunity.)
IMO, a problem is the difference between PROVABLE reinfection and probable  reinfection. Provable requires a genome sequence of the first infection and of the second infection and that they be different. Probable reinfection is a positive test, followed by no symptoms and a negative test, followed by a subsequent positive test. The low numbers you hear are provable reinfections. The Jan 29 study shows probable reinfections.
Quote:[reinfections] are different from instances of so-called long-haul Covid-19, in which the original infection triggers debilitating symptoms that linger for months and viral particles can continue to be detected. Reinfection occurs when a person is infected with Covid-19, clears that strain and is infected again with a different strain, raising concerns about sustained immunity from the disease. Such reinfections occur regularly with four other coronaviruses that circulate among humans, causing common colds.
Quote:Early studies suggested immunity would be short-lived, only a few months, while more recent research finds that certain antibodies and memory cells may persist in Covid-infected patients longer than eight months.
CDC page on COVID reinfection (as typical, says nothing).
NYPost article Feb 1, 2021 reporting on a as-yet-unreviewed Jan 29 paper.
From the Jan 29. report:
Quote:The study population comprised 3,249 predominantly male, 18-20-year-old Marine recruits. Upon arrival at a Marine-supervised two-week quarantine, participants were assessed for baseline SARS-CoV-2 IgG seropositivity,(The interpretation is what is most uncertain in an unreviewed paper.)
SARS-CoV-2 infection was assessed by PCR at initiation, middle and end of the quarantine. After appropriate exclusions, including participants with a positive PCR during quarantine, we performed three biweekly PCR tests in both seropositive and in seronegative groups once recruits left quarantine and entered basic training and baseline neutralizing antibody titers on all subsequently infected seropositive and selected seropositive uninfected participants.
Among 189 seropositive participants, 19 (10.1%) had at least one positive PCR test for SARS-CoV-2 during the six-week follow-up (1.1 cases per person-year). In contrast, 1,079 (48.0%) of the 2,247 seronegative participants tested positive (6.2 cases per person-year).
Interpretation Seropositive young adults had about one-fifth the risk of subsequent infection compared with seronegative individuals. Although antibodies induced by initial infection are largely protective, they do not guarantee effective SARS-CoV-2 neutralization activity or immunity against subsequent infection.Â
To me, the big numbers are the 6.2 cases per person-year for the people never infected and the 1.1 cases per person year for the previously infected. If those hold up, then in the situation these people are in, they will get an infection every year. (That depends partly on the frequency of exposure, which depends on the number of people with active infections. So, that 1.1 should drop as we approach herd immunity.)
IMO, a problem is the difference between PROVABLE reinfection and probable  reinfection. Provable requires a genome sequence of the first infection and of the second infection and that they be different. Probable reinfection is a positive test, followed by no symptoms and a negative test, followed by a subsequent positive test. The low numbers you hear are provable reinfections. The Jan 29 study shows probable reinfections.