Single dose of Pfizer, AstraZeneca vaccine offers 60 per cent protection: Lancet

A single dose of Pfizer or AstraZeneca Covid19 vaccine offers around 60 per cent protection against infection from SARSCoV2 in adults aged 65 years and above according to a study published in The Lancet Infectious DiseasesTo obtain realworld data on the effectiveness of these vaccines in care homes the researchers from the University College London UCL in the UK used data from the VIVALDI studyThat research investigated SARSCoV2 transmission infection outcomes and immunity in residents and staff in longterm care facilities in England for adults aged 65 years and older since June 2020This analysis included longterm care facility residents undergoing routine asymptomatic SARSCoV2 testing between December 8 2020 the date the first vaccine was administered in the study cohort and March 15 2021 using national testing data linked within the Covid19 DatastoreAlso Read Pfizer in final stages of getting approval for Covid19 vaccine in India CEOThis study was completed before the emergence of the Delta variant of SARSCoV2 now dominating in the UKThe researchers estimated the reduced risk of PCRpositive infection at 06 days 713 days 1420 days 2127 days 2834 days 3548 days and 49 days and beyond after vaccinationThis was compared with unvaccinated residents adjusting for age sex previous infection local SARSCoV2 incidence longterm care facility bed capacity and clustering by longterm care facilityThe analysis included 10412 care home residents aged 65 years and older from 310 facilities with a median age of 86 years of whom 70 per cent were female and 1155 residents 11 per cent had evidence of previous SARSCoV2 infectionA total of 9160 88 per cent residents received at least one vaccine dose during the study period of whom 6138 67 per cent received AstraZeneca and 3022 33 per cent received PfizerBetween December 8 2020 and March 15 this year there were 36352 PCR tests carried out with 1335 PCRpositive infections detected 713 in unvaccinated residents and 612 in vaccinated residentsThe risk of infection was 56 per cent lower in vaccinated residents after 28 to 34 days and 62 per cent lower at 3548 daysSimilar effect sizes at 3548 days were seen for the AstraZeneca vaccine 68 per cent reduced risk of infection and the Pfizer vaccine 65 per cent reduced riskSingledose vaccination with either the AstraZeneca or the Pfizer Covid19 vaccine reduces the risk of SARSCoV2 in older residents in longterm care facilitiesrdquo the researchers saidOur findings suggest that vaccination also has an effect on SARSCoV2 transmissibility by reducing the total number of infections in residents as well as their infectivity they saidThe protective effect of a single dose of vaccination is evident from 4 weeks to at least 7 weeks after vaccination which provides some evidence to support extension of the interval between doses beyond three weeks the researchers saidHowever even beyond four weeks a single vaccine dose does not eliminate infection risk highlighting the continued importance of nonpharmaceutical measures to control transmission within longterm care facilitiesFurther work is required to evaluate the effectiveness of the second dose of the vaccine and the effect of vaccination on transmission the researchers saidThis knowledge will be critical to inform policy decisions regarding revaccination schedules in this vulnerable population and the disease control measures needed in the short medium and long term to protect longterm care facilities from future waves of SARSCoV2 infection they addedThis 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