Other countries, like Israel, opened schools at the same time that restrictions were lifted in May on surrounding communities, which led to Covid-19 outbreaks that had infected 1,335 Israeli students and 691 staff as of July 15. In Israel, schools reopened without masking or social distancing rules, according to The Wall Street Journal, and allowed up to 40 students per class, unlike the Scandanavian nations, which had limited class size. Since May, Israel has closed 125 schools and 258 kindergartens because of outbreaks.

Despite the Israeli numbers, there are other epidemiological case studies that indicate that spread of coronavirus can be limited in schools. In the German state of Saxony, physicians from Dresden University checked blood samples from 1,500 students and 500 teachers once schools reopened in May. Only 12 came back positive for antibodies to the coronavirus, indicating a low level of community infection. Their preliminary study, which has been posted on a preprint server and not peer-reviewed by a scientific journal, also reported that even though coronavirus cases were detected in three of the 13 schools surveyed, the infection did not spread throughout the schools or the nearby community.

Among 24 households in which at least one family member had previously tested positive for Covid-19, there was only one transmission of the virus to another family member. The study authors say that means that the schoolchildren did not get infected despite living with an infected family member, and also did not pass on the virus to other schoolchildren. “Our study finds that students play a less crucial role in transmitting the virus than initially thought,” Jakob Armann, an author of the study and a pediatric infectious disease specialist at the University Children’s Hospital in Dresden, wrote in an email.

“We could not identify any hidden clusters, even in schools that had identified cases before the March lockdown,” Arman continued. “There is a way to reopen schools safely while maintaining certain measures (e.g. universal mask wearing in public transportation, in stores, no sporting events) to keep case numbers in the general population so low that you can keep students in school at the same time.”

While the German study might be considered a bit of good news for parents who want their children to return to in-person classes, there’s a big caveat. Unlike the United States, which has been plagued by a chaotic federal response and disparate measures by individual governors, German health officials followed public health guidelines and handled the coronavirus outbreak quickly once it emerged in March. Germany instituted early and widespread testing and treatment protocols, and set up plenty of intensive care beds. German citizens also trusted their government’s instructions to take precautions and widely observed social distancing guidelines.

Since then, Germany has reopened its schools, economy and sports leagues without losing control of the virus. Germany has had 206,667 cases and 9,124 deaths as of July 26, according to the Johns Hopkins University Coronavirus Resource Center.That compares to more than 4.2 million confirmed cases and 146,831 deaths in the United States, more than any other country.

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With 2,000 participants, the German study was relatively small. In epidemiology, a larger sample size can provide the kind of statistical power to bolster a conclusion about disease spread among a population. So it’s also worth looking at that study of nearly 5,700 South Korean coronavirus patients that was released this month on a preprint server by researchers at the Korean Centers for Disease Control. Through extensive contract tracing, the authors were able to track viral spread from so-called “index patients,” who are the first confirmed cases in a community cluster of infections, to the additional 59,000 people they infected. They found that children under 10 who were positive for Covid-19 had the lowest transmission rates of any age group, whereas children between 10 and 19 had transmission rates similar to adults.