(1/10) Follow-up study of household contacts of people with #COVID19, showing it’s possible to prevent transmission at home.

Daily testing showed some people may not test positive for long. One child was positive for only 2 days. Cases are easily missed.
https://wwwnc.cdc.gov/eid/article/27/2/20-3517_article

(2/10) This was a study of 5 households in Utah, conducted by the CDC. Each household had one index case. CDC staff visited each household within 2-4 days of the index cases’ positive test (day 0), for the next 4 days (day 1-4), and 14 days later. Contacts were tested each visit.

(3/10) In 3 of the 5 households, there was no transmission to other household members (0%).

In the other 2 households, all family members were infected (100%).

Overall, 7 of the total 15 contacts were infected (47%).

(4/10) The 3 households that had no transmission put isolation measures in place.

In one household, a person moved into a caravan on the property.

In another, the index case used a seperate bathroom and bedroom, and ate meals separately.

(5/10) In the third household, the index case had a seperate bedroom (and ate meals alone there), but did not have a seperate bathroom. However, he wore a N95 mask and gloves whenever he left the room.

All three households increased hand washing and/or surface disinfection.

(6/10) The other two households (in which everyone became infected) did not isolate the index case, and all household members had ongoing exposure to them.

(7/10) In one household where everyone was infected, contacts tested positive throughout the study (and at day 14), except a child who tested positive for only two days.

(8/10) Despite testing positive for only two days, it was possible to culture virus from this child. This suggests they had the potential to transmit the virus to others during this time.

The child had been symptomatic for one day before testing positive.

(9/10) In summary, the study suggests that it is not inevitable that an infected person will transmit the virus to their household contacts, provided isolation measures are taken.

(10/10) The study also shows that a single PCR test may fail to detect some infections.

One of the three children who tested positive in this study would have been missed if the child had not been repeatedly tested.