Delta variant counted for 60 per cent of Delhi cases in April: Study

The rapid surge in cases during Delhirsquos fourth Covid19 wave was mainly driven by the Delta variant which likely has immuneevasion properties and counted for 60 per cent of the cases in April according to a new studyThe Delta variant B16172 is 50 per cent more transmissible than the Alpha variant B1117 first discovered in the UK say researchers from the National Centre for Disease Control NCDC and the CSIR Institute of Genomics and Integrative Biology IGIBPrior infections high seropositivity and partial vaccination are ldquoinsufficient impedimentsrdquo to the spread of the Delta variant found the scientists They traced the factors contributing to the scale and speed of the fourth wave that started in April in Delhi and compared them to the preceding three waves last yearldquoWe find that this surge of SARSCoV2 infections in Delhi is best explained by the introduction of a new highly transmissible variant of concern VOC B16172 with likely immuneevasion properties the researchers notedThe variant may have led to insufficient neutralising immunity in people despite high seropositivity and social behaviour may have augmented the surge by promoting transmission they addedNeutralising immunity consists of naturally occurring antibodies that play an important role in the immune systemTo determine whether SARSCoV2 variants may be responsible for the April 2021 outbreak in Delhi the researchers sequenced and analysed community samples from Delhi from the previous outbreak in November 2020 until May 2021 and related it to effective reproductive number RtThe effective reproductive number is the expected number of new infections caused by an infectious individual in a population where some individuals may no longer be susceptibleThe yettobepublished paper posted on the preprint repository MedRxiv on Thursday noted that the incidence of the Alpha variant was ldquominimalrdquo in Delhi in January rapidly increasing to 20 per cent in February and 40 per cent in MarchHowever the rapidly spreading Alpha variant was overtaken in April by the Delta variant first found in Maharashtra the authors of the study notedThe proportion of the Delta variant increased from 5 per cent in February to 10 per cent in March before overtaking the Alpha variant by April and accounting for 60 per cent of the sequenced samples according to the paperThis increase in the proportion of the Delta variant was paralleled by a large increase in the positivity rate the researchers saidThe positivity rate in Delhi had jumped to over 36 per cent by April third week meaning one in every three samples being tested was found to be positive for Covid19On April 20 Delhi saw the highest spike in daily cases since the beginning of the pandemic with 28395 people testing positiveldquoWhile much more remains to be done three takeaways for now are Delta B16172 is more transmissible than Alpha B117 there seems to be greater immune escape and reinfection and fully vaccinated breakthroughs were disproportionately due to Deltardquo said Anurag Agarwal director CSIRIGIB in a tweetThe researchers also found that breakthrough infections ndash catching the virus even after vaccination were disproportionately high because of the Delta variantHowever they are yet to determine whether the variant also leads to increased case fatality ratio CFRAlso ReadB1617 variant of coronavirus drove surge in cases in last 2 months INSACOGldquoOverall we note that B16172 is capable of creating very fastrising outbreaks with vaccination breakthroughsrdquo the authors wrote in the paperldquoWe would reemphasise that prior infections high seropositivity and partial vaccination are insufficient impediments to its spread as seen in Delhi and strong public health response will be needed globally for its containmentrdquo they addedThe Delta variant of Covid19 has now become the dominant VOC in the UK and may also come with an increased risk of hospitalisation health officials in Britain have saidThis story has been sourced from a third party syndicated feed agencies Midday accepts no responsibility or liability for its dependability trustworthiness reliability and data of the text Midday managementmiddaycom reserves the sole right to alter delete or remove without notice the content in its absolute discretion for any reason whatsoever