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 🧵

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
4/ Over the same period (median 16 weeks, ~4 mths), 15% (97/656) of students & 10% (59/590) of staff seroconverted (antibody -ve ➡️+ve; captures asymptomatic infections too)

👉 there were 2-3 times as many students/staff with antibody evidence of infection vs PCR-testing alone
5/ The proportion with evidence of previous infection (Nucleoprotein (N) antibody positive) in March 2021 was 36% (370/1018) in students & 32% (245/769) in staff, but was as high as 50% in some London schools
6/ The proportion with spike protein (S) antibodies (due to infection and/or vaccine) was 40% (402/1018) is students & 60% (459/769) in staff, similar to regional community seroprevalence. Staff had higher proportion with Spike protein antibody because of vaccination
7/ For the unbelievers of #SARSCoV2 antibodies as a marker of infection, we used multiple antibody testing platforms & showed that the Roche N and S assays were the most reliable, while the Abbott N assay had uncharacteristically high antibody decay rates over time (assay effect)
8/ To conclude:

By March 2021, 1 in 3 students in urban secondary schools had serological evidence of #SARSCoV2 infection (up to 50% in London)

👉antibody rates likely higher now after Delta variant

👉these findings are important when considering vaccination of teenagers


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More from @ShamezLadhani

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…🧵

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…
Read 6 tweets
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)
Read 19 tweets
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…
Read 7 tweets
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)
Read 7 tweets
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…
Read 5 tweets
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-…
Read 9 tweets

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