Nierecenzowane badanie efektywności szczepionek w zapobieganiu transmi... (@ZapomnialWieprzJakProsiakiemByl)

Nierecenzowane badanie efektywności szczepionek w zapobieganiu transmisji.
100 000 osób zainfekowanych i 150 000 kontaktów(domownicy) w UK.
W przypadku wariantu Delta
- Pfizer 65% mniejsze szanse na pozytywny wynik u kontaktu
- AstraZeneca 36% mniejsze szanse na pozytywny wyniku kontaktu
Zaszczepione osoby maja mniejsze szanse na zarażenie się.
Ochrona przed transmisją spada z czasem.

Ciekawy fragment po poziomie wiremii i Ct testów PCR

It has been hypothesised that vaccines reduce onward transmission from infected vaccinated individuals by reducing viral loads, as higher viral loads are associated with transmission.14,15 Therefore, it is perhaps surprising we found that most of the effect of vaccines persisted after adjusting for Ct values, i.e., factors other than PCR-measured viral load at diagnosis are important in vaccine-associated transmission reductions. The single measured Ct value only approximates viral load at the time of transmission, as viral loads are dynamic over time.22 Hence, observed viral loads may not be representative of viral loads at transmission, however, the strong relationship between measured Ct values and risk of onward transmission argues against this15 (replicated here, Figure 4B). Therefore, it is possible vaccination acts by facilitating faster clearance of viable infectious virions,17,18 but leaving damaged ineffective virions behind that still contain PCR-detectable RNA. This may mean antigen assays have advantages in predicting the risk of onward transmission in those vaccinated, but this needs further study

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27,666/55,977(49%) contacts of unvaccinated index cases tested PCR-positive, as did 5,256/14,398(37%) and 9,623/36,085(27%) contacts of partially ChAdOx1 and BNT162b2 vaccinated cases, and 7,559/25,422(30%) and 1,694/7,282(23%) contacts of fully ChAdOx1 and BNT162b2 vaccinated cases. For index cases vaccinated twice with BNT162b2 or ChAdOx1 the median(IQR) days from second vaccine to an Alpha variant PCR-positive test was 41(26-62) or 27(18-43) respectively and 89(69-110) and 50(34-69) for Delta

https://www.medrxiv.org/content/10.1101/2021.09.28.21264260v1.full
#koronawirus #szczepienia #medycyna #ciekawostki