If you would like John’s text books, (it is free to download the PDFs)
Link to free download of my 2 textbooks
http://159.69.48.3/
Physiology book in hard copy
https://www.ebay.co.uk/itm/154770452796?mkevt=1&mkcid=16&mkrid=710-127635-2958-0
Do you also have significant protection even after previous asymptomatic infection?
Stefan’s original paper
https://pubmed.ncbi.nlm.nih.gov/35149106/
Original video
Question 1: Do you also have a significant protection against reinfections when your first SARS-CoV-2 infection was asymptomatic?
Answer: Yes
https://academic.oup.com/cid/advance-article-abstract/doi/10.1093/cid/ciac034/6509535?redirectedFrom=PDF
Accepted article, Clinical Infectious Diseases
Reinfection with delta data
Previous infection reduced hospitalizations by 85%
Effectiveness against symptomatic reinfection
Protection from symptomatic versus asymptomatic infection
Symptomatic previous infection, 92.9% protection
Asymptomatic previous infection, 85.9% protection
both symptomatic and asymptomatic infection appear to provide strong protection against future severe disease.
These data are extremely important as so many infections are asymptomatic
Question 2: Are the data on natural immunity also valid for the Omicron variant?
Answer: Yes, (Letter to NEJM)
Protection against the Omicron Variant from Previous SARS-CoV-2 Infection
Qatar
https://www.nejm.org/doi/full/10.1056/NEJMc2200133
In addition, we performed
sensitivity analyses that included adjustment for vaccination status and that excluded vaccinated persons from the analysis.
Protection against reinfections is moderately lower for the Omicron variant
The effectiveness of previous infection in preventing reinfection was estimated to be
90.2% against the alpha variant
85.7% against the beta variant,
92.0% against the delta variant, and
56.0%magainst the omicron variant
Protection against severe, critical or fatal COVID-19 is similar as for other variants
The effectiveness with respect to
severe, critical, or fatal Covid-19
69.4% against the alpha variant,
88.0% against the beta variant
95% to 100% against the delta variant
87.8% against the omicron variant
The median interval between previous infection and PCR testing
254 days to 376 days
Question 3: Is Omicron really not so mild?
NEJM, Challenges in Inferring Intrinsic Severity of the SARS-CoV-2 Omicron Variant
https://www.nejm.org/doi/full/10.1056/NEJMp2119682
South Africa
Answer: According to data from individuals who remained unvaccinated and did not have a previous SARS-CoV-2 infection,
the severity in terms of causing hospitalization was about 75% of the Delta variant.
Viruses don’t inevitably evolve toward being less virulent;
evolution simply selects those that excel at multiplying.
In the case of Covid-19, in which the vast majority of transmission occurs before disease becomes severe,
reduced severity may not be directly selected for at all.
Indeed, previous SARS-CoV-2 variants with enhanced transmissibility (e.g., alpha and delta)
appear to have greater intrinsic severity than their immediate ancestors or the previously dominant variant.
