1/ Household transmission of #SARSCoV2 in children & adults
This new @PHE_uk study was pre-Alpha, pre-Delta & pre-vaccine but provides important insight into household infection & transmission risks in kids & adults
Here’s what the study found … 🧵
👉 journalofinfection.com/article/S0163-…
2/ The study followed up 452 household members of 181 PCR-confirmed adult & child cases in England during Mar-Nov 2020.
Nasal swabs taken for #SARSCoV2 PCR at baseline & Day 7.
#SARSCoV2 Antibodies tested at baseline & Day 35 to detect symptomatic + asymptomatic infection
3/ 91/431 (21%) contacts were PCR +ve & 180/383 (47%) were antibody +ve at day 35 👉 194/431 (45%) contacts had PCR +/- antibody evidence of infection
After excluding 55 households with prior/co-primary cases & PCR -ve asymptomatic contacts, 75/248 *(33%)* contacts were infected
4/ There was an inverse relationship between household size & transmission rate (bigger household ➡️ lower transmission)
Secondary Attack Rates in contacts was 16% for 0-10 yr-old children but doubled to 33% in 11-18 year-olds, 36% in 19-54 year-olds & 32% in 55+ year-olds
5/ Contacts in households where index cases reported that they were isolating from other members did not experience a lower attack rate
BUT attack rates from index cases with respiratory or systemic symptoms were significantly higher than in those without such symptoms.
6/ The proportion infected who developed symptoms (78%) was similar by age (p = 0.44) though 0-18 year-olds had fewer mean number of symptoms than adults (p = 0.001) and fewer reported loss of sense of taste or smell (p = 0.0001).
8/ Having at least 1 symptom needed for community testing (fever, cough, taste/smell loss) had sensitivity of 73% & captured 132/153 (86%) symptomatic infected contacts. But 32% (64/203) contacts without serological evidence of infection also reported at least 1 of these symptoms
7/ Conclusion: Risk if #SARSCoV2 transmission in the household is high, even when the infection is introduced by a child.
The risk of young children acquiring #SARSCoV2 infection was lower than that in adults and fewer kids developed typical symptoms of Covid-19 infection
End
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