Impact of Delta and Vaccination on SARS-CoV-2 transmission risk: Lessons for Emerging Breakthrough infections

• DOI: 10.1101/2022.03.02.22271385
• Publication Date: 2022-03-03T08:25:15Z
• Authors: Kalpana Sriraman; Ambreen Shaikh; Smriti Vaswani; Tejal Mestry; Grishma Patel; Shalini Sakthivel; Vikas Oswal; Pratibha Kadam; Kayzad Nilgiriwala; Daksha Shah; Mangala Gomare; Nerges Mistry
• Keywords: 0301 basic medicine; 03 medical and health sciences; 3. Good health

Abstract With the continuous emergence of SARS-CoV-2 variants concern and implementation mass-scale interventions like vaccination, understanding factors affecting disease transmission has critical implications for control efforts. Here we used a simple adapted N95 mask sampling method to demonstrate impact circulating vaccination on 92 COVID-19 patients expel virus into air translating risk. Between July September 2021, when Delta was dominant strain in Mumbai, noted two-fold increase proportion people expelling (95%), about an eighty-fold median viral load three-fold high emitter type (41%; >1000 copy numbers 30 minutes) compared initial strains 2020. Eight percent these continued be emitters even after eight days symptom onset, suggesting probable increased risk at this stage. There no significant difference pattern between partial, full un-vaccinated individuals similar We significantly more infections among vaccinated study their household members than unvaccinated, probably due duration from and/or behaviour upon lower perceived threat. This provides biological evidence possible with emphasizing need continue appropriate behaviour. The also indicates that may useful screening future vaccine candidates, therapeutics or ability block transmission.