If Even One Family Member Gets a COVID Vaccine, Infection Risk Decreases ↓

If 4 out of 5 family members are vaccinated and 1 is not, infection risk decreases by 97%

(Photo by Yonhap News)

[Asia Economy Senior Reporter Jinsoo Lee] It has been revealed that even people who have not received the COVID-19 vaccine have a significantly lower chance of contracting COVID-19 if someone in their family has been vaccinated or has natural immunity.

Researchers at Ume? University in Sweden reported in the online edition of the JAMA Internal Medicine on the 11th (local time) that the COVID-19 vaccine not only protects vaccinated individuals but also prevents infections among those around them.

For example, in a household of five, if only one person is unvaccinated and the rest of the family members are vaccinated or have natural immunity, the probability of COVID-19 infection in that family decreases by 97%.

There was a direct correlation between the number of vaccinated family members and the reduction in infection probability. Professor Peter Nordstr?m of the Ume? University School of Medicine (Geriatrics) pointed out regarding this survey result, "Vaccination is important for the individual who receives it, but it is also very important in preventing infections, especially within families."

The researchers collected and analyzed data from 814,806 households and 1.7 million people across Sweden. Each household consisted of 2 to 5 members.

The researchers used COVID-19 infection and vaccination data to determine how many members per household had immunity, whether from natural infection or vaccination.

In all surveyed households, at least one family member was found to lack immunity. The researchers calculated the probability of these individuals contracting COVID-19. As a result, households with 4 out of 5 members having immunity were found to be the safest. The probability of contracting COVID-19 was 97% lower compared to others who were unvaccinated.

In families of 4 or 5 members where 3 had immunity, the chance of the remaining unprotected family members contracting COVID-19 was reduced by over 90%. If 2 members had immunity, the risk dropped by 75%, and even with just 1 immune member, the risk decreased by about 50%. This means that immunity, whether from vaccination or natural infection, can protect neighbors without immunity.

The researchers explained that vaccination not only protects individuals from infection but also reduces transmission, minimizing the number of people progressing to severe illness and potentially preventing the emergence of new variants.