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Vaccines play a key role in reducing transmission of the virus within families, which likely has implications for herd immunity and pandemic control. These are the conclusions of a study published in the Jama Internal Medicine journal and conducted at the University of Umea in Sweden.
Basically, if someone in the family is vaccinated or has already had Covid, their non-immunized family members are more protected from infection. And the more family members there are to be immune to the virus (either from the vaccine or from a previous infection), the greater the protection from infection and hospitalization risk for non-immune members (which is reduced by 45-97%).
The audience of subjects in the study
The work involves over 1.8 million individuals for a total of over 800 thousand families. The authors – scientists from Umea University and UIT, The Arctic University of Norway – used data from national registries to investigate the association between Covid risk in non-immune people and the number of family members protected following a previous infection. or a full vaccination.
Each family included from 2 to 5 members (more often 2 people both non-immune, more rarely 5 people of which 4 immune), mean age 51.3 years.
Risk reduction up to 97%
During a mean follow-up period of 26.3 days, 5.7% of the non-immune components of the analyzed nuclei received a diagnosis of Covid. And an inverse association was found between the number of protected members in each family and the risk of infection in the others, regardless of the size of the nuclei.