Covid-19 less likely to affect people if family members vaccinated: Study

People without immunity against Covid-19 are at a significantly lower risk of infection and hospitalisation depending on the number of family members vaccinated or have an immunity from a previous infection from Covid-19, according to a nationwide study by Umea University, in Sweden.

The research, published in the journal JAMA Internal Medicine, found that there was a dose-response association between the number of immune individuals in each family and the risk of infection and hospitalisation in non-immune family members.

Non-immune family members had a 45 to 97 per cent lower risk of infection and hospitalisation, as the number of immune family members increased, the researchers said. More than 1.8 million people from over 800,000 families in Sweden were a part of the study.

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Similar results were found regardless of whether immunity was acquired from a previous infection, a single dose of vaccine, or full vaccination.

Marcel Ballin, doctoral student at Umea and the co-author of the study said that vaccination against Covid-19 also “minimises the risk that more people become critically ill” and the new variants, which “emerge and start to take over”, mentioned a report by the Hindustan Times.

The researchers combined data from the Public Health Agency of Sweden, the National Board of Health and Welfare, and from Statistics Sweden. On the basis of the Swedish population, the study accounted for differences in age, clustering within families, socioeconomic status, and several diagnoses previously seen as risk factors for Covid-19.

The research findings suggest that vaccines are associated with a reduction in the transmission of the SARS-CoV-2 virus within families, which likely has implications for herd immunity and pandemic control.

However, a caution is warranted given the emerging variants of concern, which appear more transmissible and may be less sensitive to a single dose of vaccine, the research concluded.