The reason why children are easily able to get rid of the SARS-CoV-2 virus is due to a super-efficient innate immune system in their airways, as was hypothesised earlier (not from ‘less ACE2 receptors’).
Breakthrough infection rate is not provided for type of vaccine. Only overall number is given (13%, 81/614)
Antibody levels are seen to drop with time as expected.
Peak antibody levels are lower & the decline faster for covaxin, but this does not imply lower protection.
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The reason why a lower antibody level does not mean lower protection is that there are multiple components in the immune system that provide protection. Not all of them are measurable.
Besides, the study does not provide data that lower antibody level led to more infections.
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Multiple issues with the widely quoted NEJM Israel study on boosters
Long thread👇
1. Authors report a lofty reduction in infections & severe cases by a factor of 11.3 & 19.5 in the primary analysis, where rates are compared between boosted & non boosted groups.
2. In secondary analysis, this factor is down to 5.4. Secondary analysis compares rates within the SAME group, by timeframe. This is more believable not only because comparison is within the same group, but also because we know higher antibody levels reduce infection rates.
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Note: secondary analysis is available ONLY for infections, not severe cases.
In other words, we do not yet know if this 5.4-fold reduction in ‘infection’ will translate to reduction in hospitalisation/death later.
3. No mention of number of people who were hospitalised.
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Detailed graphical representation of the story of the US elementary school teacher who infected 12 of her masked students by reading aloud without mask.
Lessons:
1. Multiple factors have to be in place to prevent outbreaks
Large cohort of 673,676 vaccinated, 62883 past infection, & 42,099 vacc + past infection. The groups were matched to exclude confounding.
They looked at remote & recent past infection separately. Those who were infected in 2021 had greater protection than 1 year ago.
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The vaccinated group had a 27-fold greater risk of SYMPTOMATIC breakthrough infection compared to natural infection. The risk was 13-fold for ALL breakthrough infections.
A single dose of vaccine further increased the level of protection for those who had past infection.
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Audit of 281 COVID-19 deaths in Ernakulam showed that 98.2% of the deaths occurred among those who had not been (fully) vaccinated. i.e. only 1.8% of deaths were fully vaccinated.
Enhanced spread of Delta variant might not be due to “immune escape”, but rather from more efficient cell-entry mechanisms & improved replication (processing of spike protein).
Researchers tested out a “Frankenstein” delta variant fitted with an alpha spike, and found that this hybrid virus was even less efficient than the alpha itself.
P681 mutation enhances the S1-S2 furin cleavage process. This improves entry into the cell.
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P681R also helps during processing of spike protein within the cell.
Both these factors effectively mean that the virus can not only enter, but also multiply efficiently.
This translates to enormous numbers of viruses found early during infection, and thus greater spread.
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