key: cord-0847350-mhnmbt4c authors: Tokuda, Yasuharu; Shibuya, Kenji; Oguro, Kazumasa title: Priority of SARS‐CoV‐2 test, trace, and isolation in Japan date: 2020-12-04 journal: J Gen Fam Med DOI: 10.1002/jgf2.409 sha: 58ec1d8639a71dc1b8fb938117e5a845c9b40409 doc_id: 847350 cord_uid: mhnmbt4c nan The SARS-CoV-2 causes considerable transmission of infection from presymptomatic or asymptomatic people. 1 Symptomatic people can isolate themselves immediately after the symptom onset, but there are many symptomless but infected persons who are now aware of risk at possible transmission to others without any intent. Thus, if family has an infected asymptomatic or presymptomatic person and elderly or high-risk persons, the infection is easily transmitted within the family. Also, in a closed workplace or restaurant, the infection is transmitted to others. For this unique characteristic, the sole use of symptom-based strategy breaks down. 2 We need another strategy in addition to it. Many European and American countries could not contain the infection, and they have had a tremendous number of deaths. Nonetheless, in countries of western pacific regions, many countries (other than Indonesia, the Philippines, and Japan) have successfully contained it. 3 Successful countries such as China, New Zealand, or Taiwan have implemented large-scale PCR tests followed by contact trace and supported isolation. Polymerase Chain Reaction tests in Japan from February to May 2020 were limited to those with severe symptoms. Reasoning at this time was that testing all patients could cause healthcare collapse. But this reasoning was scientifically invalid, because early identification and isolation of infected persons are the most effective public health intervention in nonimmune infectious epidemics regardless of magnitude of symptoms. In May 2020, the prime minister of Japan confessed that Japan has not had enough capacity to conduct largescale PCR test. However, Japan has been reluctant in developing it for unknown reasons. 4 Nevertheless, we provide here a strategy that should be employed by the national and local governments in Japan. Where an infectious disease epidemic is ongoing, the value of Rt, which is the real-time effective reproduction number, is important. This can be regarded as the real-time mean number of secondary infections produced by one infected person. The epidemic spreads when it exceeds 1, but if it is kept less than 1, it can be suppressed. It is important to implement early public health intervention that reduces it to less than 1 in areas with the highest R. The most powerful intervention that can lower R is lockdown (a request to refrain from locking down because it is not legally possible in Japan). However, the collateral damages of refraining from going out and refraining from doing business from April to June were enormous. Thus, we should seek another way to lower Rt. Even if it is not possible to isolate everyone with infection, isolation to make R < 1 is sufficient for containment. By pushing the quarantine effort to achieve R < 1, the infection can be suppressed. Our recommendation is as follows: To do this, use PCR test, trace, and isolation (TTI) more wisely. In epidemic areas, people with symptoms need to be tested rapidly so that appropriate contact trace and iso- Currently in Japan, PCR test has been recommended only for symptomatic patients, their close contacts, and international travelers. Antigen test has been introduced for international travelers. Frequent use of antigen test combined with PCR test confirmation would also be another candidate strategy which has been implemented by Slovakia. 5 COVID-19 outbreak on the diamond princess cruise ship in Contact tracing assessment of COVID-19 transmission dynamics in Taiwan and risk at different exposure periods before and after symptom onset Resurgence of covid-19 in Japan An open letter to Japan's new Prime Minister Expansion of PCR testing is the key to an exit strategy, but which is more important, sensitivity or frequency of tests? Japan SPOTLIGHT