Originally from a Twitter thread by Dr Deepti Gurdasini
One of of the arguments used by some, including members of JCVI, has been that because of the high exposure in kids, that one dose of the vaccine may be adequate. However, the evidence actually suggests poor neutralisation in kids & rapid waning of antibodies (Abs).
Firstly, many people don't seroconvert after infection, and with young people this proportion can be even higher. This means that they may not have detectable Abs after infection. Ab levels generally do correlate with protection, so the absence of antibodies is problematic.
Of course, we cannot rule out T cell responses in these children (the other mechanism that the body uses to fight infection), but in the absence of clear evidence showing that these are present, we cannot assume this is the case, as some appear to have done.
A recent study from the CDC showing non-seroconversion (did not develop Abs three weeks after confirmed infection) in 36% of the cohort studied. Those who didn't develop antibodies were on average *10 years younger* than those who did (included adults 20+).
Predictors of Nonseroconversion after SARS-CoV-2 Infection
Nonseroconversion after SARS-CoV-2 Infection
Even when Abs are present, neutralising antibody responses measured against pseudovirus were lower in hospitalised children compared to adults who donated plasma, or who developed severe COVID-19. Here is a Nature Immunology study that showed this.
Distinct antibody responses to SARS-CoV-2 in...
Clinical manifestations of COVID-19 caused by the new coronavirus SARS-CoV-2
are associated with age. Adults develop respiratory symptoms, which can
progress to acute respiratory distress syndrome…
When Abs are present, they seem to wane fairly quickly in children - possibly because children are more likely to have mild or asymptomatic acute infections. Here's the school serology study from England showing 50% of children losing Abs within 4 months:
Let's remember Ladhani's own work showed 50% of children who were seropositive lost antibodies over just a four month period between Sep and Dec 2020
Another study looked at antibodies among infected children compared to their parents. It's very clear that children had rapid waning of immunity by 180 days, with much lower immunity at 6 months compared to their parents.
Even worse is the emerging evidence suggesting Long COVID in children is associated with lower levels of Abs during acute infection. It is very problematic to limit Long Covid studies to include only those that have serology confirmed exposure (based on presence of Abs). All those with a diagnosis of Long Covid should be included even where this was based on clinical history (this is highlighted as appropriate in the NICE guidance).
Similar can be seen in hospitalised patients. Ab levels predict long COVID, so antibody positivity *should not* be used to assign people 'exposure' or 'caseness' when examining Long Covid, because this will just lead to misclassification & underestimating prevalence.
The above paper was on non-hospitalized long haulers, but is consistent with this paper that *also* found that low IgG levels were a risk factor for developing #LongCovid in hospitalized patients.
The 1st prospective study (preprint) to determine risk of developing
#LongCovid (at least that I've seen)
Notable risk factors among 146 patients were female sex (lower 95% CI .96), @WHO severity, and (lower) peak IgG antibody titer to spike protein
- young people tend to have lower seroconversion at acute stage -Abs in children less likely to be neutralising than adults
-Abs in children wane faster than in adults
- We don't know enough about T cell immunity, but we cannot assume children are protected this way without evidence
And, even if kids had Abs, let's be very clear - this doesn't always mean protection against the delta variant, which is able to escape even from immunity to previous lineages to some extent. Vaccines provide immunity through a safe mechanism, and boost immunity for those with prior infection.
So, this is a plea to everyone talking about 'naturally immunity' in the 'majority of children', or natural immunity in children being sufficient and them needing either no or one dose of vaccination - please cite evidence for these claims, or stop pushing unevidenced misinformation.
Please feel free to link this thread to anyone who uses these unevidenced narratives. The problem is that these narratives will likely lead to vaccine hesitancy, despite these claims being made without evidence. It's disappointing to have seen these repeated again & again by members of JCVI & PHE.
Also, to those talking about rigour and case-control studies in Long Covid, please take a moment to consider how you would minimise misclassification among controls, given the sheer number of children infected and the low pick up from serology *and* PCRs in kids.
Unless you're able to discuss the limitations of these case-control analyses in a sensible way, please don't pretend these are rigorous just by virtue of having a control, without any consideration of what that control is.
Extrapolated from Sep 20, 2021 • 15 tweets • dgurdasani1/status/1439905644409245696
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short film on the long-lasting symptoms of Covid in children.
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