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Shamez Ladhani Profile picture
@ShamezLadhani
Jul 29, 2021 • 6 tweets • 4 min read • Read on X
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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…
4/ Across England, for both #COVID19 vaccines, effectiveness (VE) was ⬆️ in all age-gps from 14 days after dose 2 vs dose 1, but varied with dose interval, with higher 2-dose VE when Pfizer doses were given >6 weeks apart compared to a 3-week schedule, including ≥80 year-olds
5/ When assessing vaccine effectiveness (VE) by interval between the two #COVID19 vaccine doses, the “sweet spot” does seem to be around the 8 week interval for the two vaccines, which supports the recent national recommendations to reduce the dose interval from 12 to 8 weeks
6/ In summary,

- The violin plot👇 shows nicely how extending interval between #COVID19 vaccine doses improves immune response after 2nd dose

- Remember that extending dose interval to 12 weeks meant many more older adults could be vaccinated quicker with limited vaccine supply

• • •

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More from @ShamezLadhani

Shamez Ladhani Profile picture
Jan 30, 2023
1/ Remember all the media coverage of #omicron causing so much severe #COVID19 in young kids?

We extended our @UKHSA #COVID19 deaths surveillance in kids & found:

ONE #COVID19 fatality per MILLION #Omicron infections in children aged <20 yrs …🧵

👉 sciencedirect.com/science/articl…
2/ We assessed all fatalities within 30 days of a positive #SARSCoV2 test in <20 year-olds during Jan-Mar 2022 when national testing was still available. We collected detailed clinical data from multiple sources to ascertain cause of death for each child
3/ During Jan-Mar 2022, there were 46 deaths within 30 days of a positive #SARSCoV2 test & 11 were due to COVID-19

👉All 11 #COVID19 deaths occurred after primary SARS-CoV-2 infection

👉 8/11 (73%) had underlying comorbidities, including 4 with severe neurodisabilities Image
Read 9 tweets
Shamez Ladhani Profile picture
Dec 30, 2022
1/ This is so mportant - thank you @kerpen for tagging me

The US with all its mitigations, vaccine & booster mandates has the same proportion of kids already exposed to #sarscov2 as the UK, which as been accused of “letting the virus rip”

90.3% (US) vs 86.7% (UK)

…🧵
2/ In England, among 1-17 year-olds, we recently reported that by Sep 2022

➡️ 86.2% (95%CrL 81.1-91.6) had infection-induced #SARSCoV2 N antibodies

➡️ 97.2% (95% CrI 93.7%–98.9%) had #SARSCoV2 S-antibodies (infection and/or vaccine)

👉 journalofinfection.com/article/S0163-…
3/ According to US CDC, #SARSCoV2 antibody seroprevalence in 6m-17y by Sep-Oct 2022 was no different:

➡️ 90.3% (95%CI 89.8-90.8) had infection-induced N antibodies

➡️ 95.9% (95%CI 95.5-96.3) had S-antibodies (infection and/or vaccine)

👉 covid.cdc.gov/covid-data-tra…
Read 5 tweets
Shamez Ladhani Profile picture
Dec 28, 2022
1/ Our @UKHSA paper on paediatric #SARSCoV2 antibody prevalence in England is now published

By Sep 2022, 97.2% of 1-17 year-olds had #SARSCoV2 antibodies

Our findings are critical for future #COVID19 vaccine/booster recommendations for kids

…🧵

👉sciencedirect.com/science/articl…
2/ Methods: We used residual samples from kids aged 1–17 years having a blood test as part of their clinical management in 44 hospital trusts in England. Samples were processed using Roche Elecsys assays for i) nucleocapsid (N) antibodies and ii) spike RBD (S) antibodies
3/ The overall national prevalence estimate of #SARSCoV2 antibody seropositivity in 1-17y, weighted by age & NHS region, based on Spike protein (vaccine or infection) increased from

➡️ 48.5% (95% CrI 40.8%–55.1%) during Sep-Oct 2021
to
➡️ 97.2% (95% CrI 93.7%–98.9%) by Sep 2022 Image
Read 8 tweets
Shamez Ladhani Profile picture
Dec 5, 2022
1/ Our latest paper on longitudinal follow-up of teens with long covid (CLoCk) is a game changer:

Different teens report the same post-covid symptoms at 0, 6m & 12m after their #SARSCoV2 PCR , irrespective of whether they tested + or - for the virus

👉 sciencedirect.com/science/articl…
2/ Method: we followed up 11-17y with a PCR-positive #SARSCoV2 test compared with matched PCR-negative controls for 12 months after their test. The final cohort included 2,909 cases and 2,177 controls
3/ We found that teens reporting a symptom at baseline (PCR-testing) improved by 6m, with new teens reporting the same symptoms at 6m, who then improved by 12m, with new kids reporting the same symptoms at 12m and so on …. you catch the drift .. 👇
Read 9 tweets
Shamez Ladhani Profile picture
Nov 18, 2022
1/ It’s really sad that, when we report that a disease (eg. #covid19) is more severe or fatal in kids with underlying conditions (eg neurodisabilities, immunocompromised), this is taken to mean that such kids are less valued

The truth is exactly the opposite…🧵
2/ It is really important that we identify kids at increased risk of severe outcomes after any condition (eg #COVID19) so we can raise awareness among clinicians, parents & policymakers to be extra vigilant & implement additional strategies protect them 👉journals.plos.org/plosmedicine/a…
3/ When kids with severe neurodisabilities were identified as high-risk in the 1st pandemic wave, the UK recommended #COVID19 vaccines for 12+y kids with severe neurodisabilities as soon as vaccines were licensed in adults - way back in Jan 2021 👉 adc.bmj.com/content/106/12…
Read 7 tweets
Shamez Ladhani Profile picture
Nov 17, 2022
Remember that recent US paper on #covid19 vaccination for 5-11y?

We didn’t agree with the conclusions (h/t @ProfAsmaKhalil)

So, we wrote to @NEJM to explain why US data do NOT support BOOSTERS for kids irrespective of their previous infection status

👉 nejm.org/doi/full/10.10… Image
2/ We pointed out that there was very little difference in protection against omicron infection between vaccinated & previously infected 5-11y, while infection plus 2 vaccine doses might provide slightly better protection after 4 months (79.4% vs 62.9%)

👉nejm.org/doi/full/10.10…
3/ We then pointed out that #COVID19 hospitalizations were v low in 5-11y irrespective of vaccination status (0.3-0.5%), although we still aren’t sure how these were calculated because numerator/denominator in their table give lower percentages (0.1%)🤷🏻‍♂️

👉nejm.org/doi/suppl/10.1…
Read 6 tweets

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