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A great article summarising our current understanding about asymptomatic infections
About 1 in 5 people w/ #COVID19 will experience no symptoms whatsoever, they have shorter viral shedding & will transmit to significantly fewer ppl than someone w/symptoms https://www.nature.com/articles/d41586-020-03141-3
About 1 in 5 people w/ #COVID19 will experience no symptoms whatsoever, they have shorter viral shedding & will transmit to significantly fewer ppl than someone w/symptoms https://www.nature.com/articles/d41586-020-03141-3
Our new paper on asymptomatic infections is published in @TheLancetInfDis - we discuss why persistently asymptomatic infections have been overestimated and describe major methodological issues that hinder attempts to estimate this fraction. #COVID19 1/ https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(20)30837-9/fulltext
People w/persistently asymptomatic infection experience no symptoms throughout the infection, pre-symptomatic individuals become infectious days before symptom onset & there are also individuals w/ mild symptoms who otherwise feel well. But these often get mixed up. 2/
Incomplete symptom assessment misclassifies people w/ mild or atypical symptoms as asymptomatic. Studies with inadequate follow-up misclassify pre-symptomatic individuals. Serological studies rely on poorly defined antibody responses & retrospective symptom assessment. 3/
It is now becoming clear that truly asymptomatic infections make up smaller % of infections. Two systematic reviews that only included studies w/ sufficient follow up have estimated the proportion to be 20% (95% CI 17–25%) and 17% (95% CI 14–20%). 4/ https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1003346
Evidence is starting to emerge about the influence of individuals' infectiousness on transmission. While asymptomatic individuals can transmit the virus to others, they seem to be 1/3 infectious compared to symptomatic individuals. 5/ https://twitter.com/mugecevik/status/1308080071324962816?s=20
This may be due to shorter duration of infectiousness. While asymptomatic individuals have similar initial viral loads when compared with people w/ symptoms, asymptomatic people seem to clear the virus faster and are infectious for a shorter period. 6/ https://www.thelancet.com/journals/lanmic/article/PIIS2666-5247(20)30172-5/fulltext
So, misclassification of asymptomatic fraction precludes our understanding of COVID19. Overestimation limits our ability to identify the best strategies for controlling the epidemic and obscures other mitigation measures that are important in preventing onward transmission. 7/
In this article, we make six recommendations to accurately define and report truly asymptomatic infections going forward. This was a fantastic collaboration h/t @EricMeyerowitz @AaronRichterman @BogochIsaac @nicolamlow 8/ https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(20)30837-9/fulltext
