A previous publication of the authors has shown a significant shortening of the serial interval – the time from symptom onset of the primary case to symptom onset of secondary… Click to show full abstract
A previous publication of the authors has shown a significant shortening of the serial interval – the time from symptom onset of the primary case to symptom onset of secondary cases – in household clusters from wild-type to Alpha and Delta variant of concern (VOC) (4.8; 4.5; 4.0 days) [1]. Since December 2021 the VOC Omicron is circulating in Germany, and since calendar week (CW) 2 it surpassed a level of 80% of infections [2]. As Omicron was ‘ spreading at a rate … not seen with any previous variant ’ [3] it was unclear if the rapidity of the rise in case numbers was due to an increase of transmissibility or a shortening of the serial interval, or both.Toextend the findings from our previous paper also to the period when Omicron dominated In a subanalysis we also investigated the serial interval for the lineages BA.1 and BA.2 of Omicron and found mean values of 3.88 days (95% CI 3.79 – 3.97) and 3.39 days (95% CI 3.30 – 3.49). Here, we used all cases in household outbreaks of CW 2 – 5 for BA.1 and CW 11 – 16 in which BA.2 was dominating in Germany.Thus,serial interval of household cases seems to have shortened even more for the Omicron variant compared to any of the variants before. This trend seems to continue even for the lineages of Omicron, BA.1 and BA.2. Results of our analysis are consistent with those from Abbott et al . who estimated a mean generation time for Omicron as 2.5 – 4 days (90% credible interval)
               
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