Expanding on a prior study conducted in rural Gandhinagar that looked at secondary attack rates (SAR) in households with Covid infections, researchers at the Indian Institute of Public Health (IIPH) in Gandhinagar have now suggested that the SAR is much higher in households with Covid deaths — indicating that mortality can be used as a surrogate marker.
The SAR is defined as the probability that an infection occurs among susceptible people within a specific group.
The researchers found 25 per cent of such houses surveyed to have secondary infections and concluded that such homes needed to be extra vigilant as death indicated a higher viral load in the patient.
Published as a preprint on November 21 and authored by assistant professor at IIPH-G, Komal Shah, public health student at New York University Nupur Desai and IIPH-G director, Dr Dileep Mavlankar, the latest study remains to be peer-reviewed and published. However, Shah said the findings have government policy implications as greater SAR in households with Covid deaths implies that “contact tracing, testing, quarantine and close surveillance of death cases must be done,” as is also mentioned in the study paper discussion.
The study has included 28 of the 49 Covid deaths in Gandhinagar in August, and found 27 secondary infections in the 28 households — indicating a 25 per cent SAR. Of these 27 secondary cases, two died later.
However, Shah said the death rate in the latest study cannot be correlated to the one found in secondary infections in the previous study, considering the lower sample space.
It was an observation in the earlier study — that secondary transmission was higher in households where primary cases succumbed to the infection — which led to this study.
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