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https://www.nature.com/articles/d41586-020-03141-3

What the data say about asymptomatic COVID infections

Article basé sur trois études, dont deux en pre-print. Je retiens la seule valide :

Estimating the extent of asymptomatic COVID-19 and its potential for community transmission : Systematic review and meta-analysis

https://jammi.utpjournals.press/doi/10.3138/jammi-2020-0030

Résultats : Les chercheurs ont extrait 2 454 articles, dont 13 études à faible risque de biais de sept pays dans lesquelles 21 708 personnes à risque ont subi le test de dépistage, soit 663 cas positifs et 111 cas asymptomatiques. Le risque relatif [RR] de transmission de cas asymptomatiques était plus faible de 42 % que celui de cas symptomatiques (RR combiné de 0,58 ; IC à 95 %, 0,34 à 0.99, p = 0,047).

Conclusions : L’évaluation de la prévalence d’un sixième de cas asymptomatiques de COVID-19 et de taux de transmission de cas asymptomatiques est inférieure à celle de nombreuses études hautement publicisées, mais suffit tout de même pour justifier l’intérêt de la santé publique. D’autres données épidémiologiques solides s’imposent de toute urgence, y compris dans des sous-populations comme les enfants, pour mieux comprendre l’effet des cas asymptomatiques sur la pandémie.

Data analysis

Diagnosis in all studies was confirmed via RT-PCR and in two cases was supplemented with radiological evidence

Five studies reported data on secondary infection transmission from asymptomatic cases. The asymptomatic transmission rates ranged from none to 2.2%

Only 5 of the 13 studies provided data on transmission rates from asymptomatic cases. The transmission risk from asymptomatic cases appeared to be lower than that of symptomatic cases, but there was considerable uncertainty in the extent of this

A further important limitation was the poor reporting of symptoms, which was often simply dichotomised into symptomatic versus asymptomatic without clear definitions and details of possible mild symptoms. […] Finally, all included studies relied on RT-qPCR ; hence, some cases might have been missed because of false-negative results, especially when study participants were only tested once. If the tests missed more asymptomatic cases, then the true proportion of asymptomatic cases could be higher than our estimates. However, false-positive results, which may occur when people without symptoms are tested in low-prevalence settings, would mean the true prevalence of asymptomatic cases was lower than our estimates.

The issue of persistent PCR positivity after a person has recovered from infection might be of concern to more recent studies conducted at some time after the first wave of the pandemic.