Gates Package — page 977

if anyone calls me about contact 1e. In two counties in North Carolina, ys one apps like the ones deployed by many If you read the previous two paragraphs and thought, if anyone calls me about contact tracing, I'm not picking up the phone, you're not alone. In two counties in North Carolina, between a third and half of COVID-infected people who were reached claimed not to have had contact with a single person in the two days before they tested positive. And many of the contacts who were named never returned the tracer's phone call.13 But contact tracing is always going to be an important part of stopping the spread of a disease, so we have to figure out how to get people to share their contacts. One of the reasons people hesitate to respond is the fear that their contacts will have to go into quarantine, but fortunately, broad quarantines of every single contact might not always be necessary. In England, some schools had their students stay home for ten days if they had come into contact with someone who had COVID. Other schools allowed the kids to keep attending school, as long as they tested negative every day. This daily testing, it turns out, was just as good at preventing outbreaks, but without having to keep students home from school.14 And contact tracing can still be effective even if it's not done as intensively as Vietnam and South Korea did. In general, if you start the program when only a small fraction of the population is infected, and if you identify a large share of cases in your country, contact tracing can cut transmission by more than half.15 And smartphone apps like the ones deployed by many states in the U.S. and around the world can help identify possible contacts while still protecting people's privacy. One problem was that, with COVID, conventional contact tracing isn't an especially efficient use of resources, because the virus is not transmitted at the same rate by everyone who's infected. If you get the original COVID strain, the chances are not especially high that you'll pass it along to someone else. (About 70 percent of those cases may not transmit to anyone else