It is not a straightforward process like deciding between 'pregnant & non-pregnant'. It is easy to under-count (a frequent complaint), and also over-count.
Let's take a look at WHO, ICMR & Public Health England's definitions. See thread.
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2/9 (see whole thread)
This is the WHO's definition of COVID-19 death.
It was written on 16 April 2020, at a time when the complete picture of COVID-19 was not known.
We now know that COVID-19 is much more than a viral illness; delayed deaths occur.
These delayed deaths may follow a period of apparent clinical recovery, that is when the patient feels better.
The ongoing immune process inside the body could last for weeks, when vascular events such as stroke, heart attacks and pulmonary emboli have been well-described.
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In other words, the WHO's definition almost (indirectly) implies that a COVID-19 death must necessarily occur during the INITIAL phase of COVID-19.
This definition fails to acknowledge that multiple lethal complications could occur after a period of apparent improvement.
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By saying "there should be no period of complete recovery from COVID-19 between illness and death", we could be missing deaths due to vascular events, which in fact were due to the (largely silent) immune process that was ongoing: not everyone gets lab tests after discharge.
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That statement (see highlighted text in pic) may be replaced by:
"If death occurs in the initial few weeks following apparent recovery, the possibility of COVID-related complication must be first ruled out before certifying as non-COVID death"
7/9
ICMR's guideline on COVID-19 death mirrors that of WHO.
Public Health England on the other hand, realized they were initially "over-counting" deaths, and soon revised their definition to deaths <28 days. This reduced death count by up to 25%. They have kept a second category too, based on a 60-day mark.
Defining death in COVID-19 will remain a contentious matter; it is impossible to have a universally accepted definition.
However, old definitions will need to be updated to avoid excluding those who died as a result of the disease in the weeks following initial 'recovery'.
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Among 506 healthcare worker infections from a cohort of 12,248 at PGI Chandigarh, 64% were unvaccinated, 9.5% were fully vaccinated (>2 weeks past II dose)
However, the shorter follow up post 2nd dose (time bias) means the real % could be higher.
The graph does not factor in the duration of follow up. During an ongoing vaccination process, those who are unvaccinated “get longer time” (compared to the vaccinated healthcare workers) to pick up the infection.
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Cont’d
Since vaccination takes time, those who were 2 weeks past second dose in the pie chart would have had fewer days of observation, than others.
This means that the odds of picking up infection will be smaller by default. This also gets reflected in the pie chart.
Rare study that demonstrates long-lived plasma cells (that make antibodies) in the bone marrow of those who recovered from COVID-19, after 7-11 months.
-This study looked the body's ability to generate antibodies long-term.
-We know that S-specific antibody levels in blood drop for about 4 months, & then level off.
-That however does not mean we 'lost' the ability to make antibodies.
-Let us look @ some basics first.
3/13
-During infection, B cells pick up the antigens of the virus and present them on Class II MHC to CD4 T cells in the germinal centres in lymph node or spleen. This activates B cells, generating memory cells and plasmablasts. Some of these mature into long-lived plasma cells.
This study involved 36,659 HCW who had easy access to testing, was done during a surge and involved relatively younger people.
Of these, 28,184 completed 2nd dose by the time of publication, of these, 14,990 were 2 weeks past 2nd dose.
See research letter attached above.
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We must also remember that the age profile of this cohort is young; their baseline risk of developing severe disease is relatively low. The key point in this study is that they had some level of mandatory testing, which means lower chance of missing infections.
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From Doctors, to Doctors.
25 Practical Tips for Doctors Treating COVID-19.
These pearls are based on the collective experience of several doctors who have been meeting every Tuesday 8 PM @ IMA Cochin, ever since the pandemic started.
Surge in Vietnam 🇻🇳 coincides with the discovery of B.1.617.2 with an additional mutation: Y144 deletion which had been seen in various settings (B.1.1.7 variant, and also in immunosuppressed patients who harboured longer SARS-CoV-2 virus infections)
Multiple mutations occurred while the SARS-CoV-2 virus lived for a long time in a immunocompromised B-cell-depleted patient. Such studies provide a rare opportunity to follow viral adaptive evolution. The Y144 deletion was first spotted ~a year ago.