Masking and isolating reduced Omicron spread in homes, CDC finds

The Omicron strain of the coronavirus has been so contagious that it may have seemed a foregone conclusion that if one person in a household got sick, other people living there would also get the virus.

But that turns out to be less certain: A small study of households by the Centers for Disease Control and Prevention released Friday found that when the first infected person wore a mask, they stayed in a separate room at least part of the time. , the risk of other household members contracting the virus was significantly lower.

Vaccinated people who became infected were also significantly less likely than unvaccinated people to spread the virus to other members of their household.

Still, the study highlighted how aggressively the Omicron variant had spread in a home, especially among people living with children under 5 who tested positive. Those children, who are not yet eligible for vaccines and often need closer contact with their parents or relatives, spread the virus to 72 percent of household contacts identified in the study — the highest percentage of any age group, the CDC said. .

“These findings further highlight the potential contribution of young children to household transmission,” CDC scientists wrote in the report.

Federal regulators are waiting for data on how well three doses of the Pfizer-BioNTech coronavirus vaccine work in children under age 5 before deciding whether to approve the vaccine for that age group.

The CDC study was based on 183 households in four states where someone became infected with the Omicron variant from November to early February. After interviewing household members about their vaccination and infection histories, any precautions they took in the home, and whether they had tested positive or become ill, CDC scientists determined that the variant had spread to about two-thirds of the households they identified. .

But when the first infected person was fully vaccinated, only about 44 percent of household members developed Covid, compared with 64 percent when the infected person was not vaccinated, the study said.

And when the original infected household member was alone in a room at least part of the time, only 41 percent of other household members became infected, compared with 68 percent in situations without isolation. Masking by the infected person also helped reduce the chance of transmission to 40 percent from 69 percent.

Determining the precise risk of spreading the virus in a home was difficult, the study authors noted. They ruled out situations where it was unclear who first developed Covid and did not do the genetic sequencing necessary to ensure that people had contracted the virus from the infected person in their homes rather than at other gatherings.

This post Masking and isolating reduced Omicron spread in homes, CDC finds

was original published at “https://www.nytimes.com/2022/02/25/health/cdc-omicron-masks-isolation.html”