Shamez Ladhani Profile picture
Paediatric infectious diseases specialist @StGeorgesHospital, Epidemiologist @PHE_uk #vaccines #meningitis #childhoodinfections
31 Jul
1/ Our preprint on #SARSCoV2 infection & transmission in secondary schools following the emergence of the Alpha variant in England is now online

We took multiple blood samples from ~2,000 students/staff for #SARSCoV2 antibodies. Here’s what we found 🧵

👉medrxiv.org/content/10.110…
2/ In England, #Covid19 cases due to the Alpha variant increased rapidly from late Nov 2020, leading to national lockdown in Dec 2020, including school closures. When schools reopened fully in Mar 2021, we took blood samples from 1,895 students & staff in our sKIDsPLUS study
3/ Between December 2020 & March 2021, 5.6% (61/1094) students & 4.4% (35/792) staff had laboratory-confirmed SARS-CoV-2 infection.

Most of these infections were acquired during community peaks in infections rates in December 2020, with a trickle of cases throughout lockdown
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29 Jul
1/ It was the JCVI that used basic immunological principles of vaccination to recommend a 12-week interval between #COVID19 vaccines to save more lives during the Alpha wave in the UK

Our paper (preprint) here shows why that was the right decision…🧵

👉medrxiv.org/content/10.110…
2/ We tested #SARSCoV2 antibodies in adults aged 50-89 years and found that, for both Pfizer & AZ vaccines, 95% had seroconverted (developed antibodies) by 35-55 days after the first #COVID19 dose, and 100% by 7+ days after the second dose

👉 medrxiv.org/content/10.110…
3/ BUT, when the vaccines were given 9-11 weeks apart, antibody levels at 2-5 weeks after 2nd dose were 6x ⬆️ for Pfizer (6703; 95%CI, 5887-7633) than AZ (1093; 806-1483), which in turn were higher than Pfizer given 3-4 weeks apart (694; 540 - 893) 👉medrxiv.org/content/10.110…
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27 Jul
1/ On 19 July 2021, JCVI published their statement on #Covid19 vaccination for 12-17 yr-olds

If you only heard that JVCI did not recommend vaccine for teens then you missed out on a wealth of information & recommendations in the report

Here’s why 🧵

👉 gov.uk/government/pub…
2/ First, the MHRA & JCVI have very different functions. The MHRA authorises medicines, including vaccines, & monitors their safety but does not make vaccine recommendations. The JCVI makes recommendations on vaccines for the national immunisation programme & for risk groups
3/ JCVI took rather long to release their statement on vaccinating 12-17 yr-olds because risk-benefits of vaccinating this age-gp
were finely balanced between risk of severe #Covid19 & risk of rare but severe side-effects for the only vaccine licensed for 12-15 yr-olds (Pfizer)
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21 Jul
1. Most of us do not really appreciate how resilient children and their immune systems are when they encounter #sarscov2. Most kids don’t even realize they have been exposed, which leads to ⬆️⬆️⬆️ over-estimation of the long-term effects of #COVID19 in children

Here’s why … 🧵
2/ when asked, most parents don’t even realize when they child was exposed to #SARS_CoV_2 because most kids either remain asymptomatic or have such a mild and transient illness that parents don’t even associate the illness with #COVID19
3/ In our primary schools study, although small numbers, parents reported no symptoms in 85% of kids who didn’t have #SARS_CoV_2 antibodies at start of the study & then developed antibodies during the study (ie. got infected) compared to 47% of staff
👉 thelancet.com/journals/lanch…
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16 Jul
1/ We studied the quality,
quantity and persistence of #SARSCoV2 antibodies in primary school students (6-11 year-olds) compared to staff (adults) over 6 months (until ~7-8 months after their #SARSCoV2 infection)

Here’s what we found (pre-print) 🧵

👉 medrxiv.org/content/10.110…
2/ The proportion of students & staff who had #SARSCoV2 antibodies in back June 2020 was similar:

👉 11.5% (95%CI, 9.4-13.9) & 11.3% (95%CI, 9.2-13.6; p=0.88) students had nucleoprotein & RBD antibodies vs 15.6% (95%CI, 13.7-17.6) & 15.3% (95%CI, 13.4-17.3; p=0.83) staff
3/ Live virus neutralising activity (ability of antibody to kill #SARSCoV2) was detected in 79.8% (71/89) of N antibody & 85.5% (71/83) of RBD antibody positive kids. RBD correlated more strongly with neutralising activity (rs=0.75; p<0.0001) than N antibodies (rs=0.37; p<0.0001)
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16 Jul
1/ We developed & validated an oral fluid assay to measure #SARSCoV2 antibodies. Basically it’s a lollipop stick with a sponge that collects oral fluid (saliva) from around cheeks/gums. Kids can do the test themselves & sample can be posted to the lab 🧵👉 medrxiv.org/content/10.110…
2/ Here’s the technical stuff: We used contemporaneous blood & oral fluid samples from ~2,000 kids & adults taking part in our school studies and developed 3 different oral fluid assays for testing & validating: N-antibody, Spike-antibody & RBD-antibody 👉 medrxiv.org/content/10.110…
3/ The N-protein capture assay was the best candidate, sensitivity 75% (95%CI, 71–79%) specificity 99% (95% CI: 78–99%) when compared with paired serum antibodies, but higher sensitivity in kids (80%, 95% CI: 71–88%) than adults (67%, CI: 60%-74%) 👉 medrxiv.org/content/10.110…
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11 Jul
1/9. In England, #SARSCoV2 infection rates in school-aged kids & #COVID19 outbreaks have both ⬆️ in recent weeks (latest data 4 July) but that does not change the narrative on kids & their role in infection/transmission in school

Here’s why … 🧵

👉 assets.publishing.service.gov.uk/government/upl…
2/9. No one has claimed that kids don’t get infected or don’t transmit #SARSCoV2 to others. But the data suggest that lower risk with kids than adults. Eg. We don’t see two-thirds of staff/students infected in a single outbreak as we do in care homes 👉 thelancet.com/journals/eclin…
3/9. We & others have shown that #SARSCoV2 cases & outbreaks reflect community infection rates. Cases in kids generally follow adults *unless* adults are in lockdown & kids continue to go to school. This happened in Nov/Dec 2020 & Mar/Apr 2021. See👇👇

👉 journalofinfection.com/article/S0163-…
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10 Jul
1/5. Mental health of Adolescents in the Pandemic: Long-COVID19 or Long-Pandemic Syndrome? (pre-print, thanks @MaryKRe)

Here’s another case-control study on long covid that measured #SARSCoV2 antibodies in teenagers

Here’s what they found … 🧵

👉 medrxiv.org/content/10.110…
2/5. 1560 kids (median age 15y):
- 188 (12%) seropositive (exposed to #SARSCoV2)
- 1365 (88%) seronegative (never exposed)

If you think this sample size is small, try bleeding 1500 teens!

They were asked the same questions ➡️ responses were near-identical in cases & controls
3/5. The authors did a subgroup analysis & found near-identical responses in teenagers who knew their #SARSCoV2 infection status vs those who didn’t

Yes, small samples size, but not even a signal of any difference in mental health status (see table👇)

👉 medrxiv.org/content/10.110…
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9 Jul
1/4 Childhood #COVID19 deaths. This preprint by @RCPCHtweets & @PHE_uk provides critical new information about #SARSCoV2 and kids which we didn’t have until now. Here’s why the small numbers in this paper matter 🧵

👉 researchsquare.com/article/rs-689…
2/4 Death is the most objective outcome & can be accurately measured in countries like England. The results show ~3,000 of 12 million kids died in 1 year & only 61 with #SARSCoV2. Detailed medical record analysis showed only 25 (42%) died *of* #COVID19

👉 researchsquare.com/article/rs-689…
3/4. Of the 25 kids who died of #COVID19, 19/25 (76%) had underlying conditions & of these 15/19 (60%) had a life-limiting condition & mostly with 2 or more medical conditions, esp. severe neurological conditions

👉 25 fatalities = 2 per million kids

👉researchsquare.com/article/rs-689…
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9 Jul
1/5 Both Pfizer & AZ vaccines are highly protective against severe #COVID19, especially after 2 doses.

Here’s why it’s better to stick to the same vaccine brand for both #COVID19 vaccine doses even after severe reaction following the 1st dose 🧵

👉 papers.ssrn.com/sol3/papers.cf…
2/5 Compared to 2 doses of the same vaccine brand, mixing Pfizer/AZ vaccines was associated with higher rates of severe reactions & requiring medical attention after the 2nd dose: esp. in younger adults, in women & in those with previous #COVID19 🧵

👉papers.ssrn.com/sol3/papers.cf…
3/5 Adults who had a severe reaction after their 1st dose of #COVID19 were more likely to have a severe reaction after 2nd dose, whichever vaccine they received, but risk of severe reactions increased if 2 different vaccine (AZ/Pfizer) brands given 🧵

👉 papers.ssrn.com/sol3/papers.cf…
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21 Jun
1/ News outlets & people on social media have been misinterpreting data on exposures prior to diagnosis as places where people caught #SARSCoV2 (provided in the @PHE_uk Weekly Reports)

Here’s why .…

👉 news.sky.com/story/covid-19… Image
2/. UK has been in lockdown since Nov. In Mar 2021, only schools reopened ➡️ 9 million children & education staff were out in the community. The figure below shows that a person was attending school prior to testing +ve for #SARSCoV2 - not that they caught #SARSCoV2 in school Image
3/ But as we eased into step 3 of opening lockdown, people were more likely to have visited other venues prior to testing +ve for #SARSCoV2

Here’s the same graph for the latest week reported. Eating out & “other” are now more frequent because restaurants & shops are open 👇 Image
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