When comparing the impact of Covid in different countries, Japan is a clear outlier. In 2020, the country had zero days of mandatory business closures and zero days of mandatory stay-at-home orders. Despite seeing less change in mobility than major European countries, Japan has not had any excess mortality since the pandemic began.
As you may recall, the country hosted the Summer Olympics between 23rd July and 8th August. But even that did not lead to a large number of deaths. It has been suggested that Japanese people, and perhaps East Asians in general, have some degree of prior immunity to the virus.
In January of this year, Japan introduced restrictions on businesses for the first time. Specifically, 11 prefectures (including the capital, Tokyo) prohibited bars and restaurants from selling alcohol after 7pm, and forced them to close at 8pm.
In a recent preprint, Reo Takaku and colleagues investigated the impact of these measures on the spread of Covid. They began by checking whether the measures had their intended effect – of reducing the number of people frequenting bars and restaurants. This cannot be taken for granted: the night curfew in Greece had virtually no impact on mobility.
The researchers analysed survey data collected in the autumn of 2020 (when there were no restrictions in place) and the winter of 2021 (when there were restrictions in place). As the chart below indicates, the measures do appear to have had their intended effects.
The x-axis represents how far respondents lived from the border of a prefecture that introduced restrictions. The blue and green lines (corresponding to the right-hand y-axis) show the fraction of people who went to a bar or restaurant at least once in the relevant month.
The blue line corresponds to the autumn of 2020, and the green line corresponds to the winter of 2021. Notice that the green line is substantially flatter than the blue line, but only on the right-hand side of the chart. This suggests that restrictions did reduce the number of people frequenting bars and restaurants.
Next, the researchers examined whether the measures actually reduced the spread of Covid. To do this, they compared self-reported symptoms among individuals living either side of the border of a prefecture that introduced restrictions. They also controlled for a number of characteristics, such as age, marital status and household income.
As the chart below indicates, they found no evidence that the measures reduced the spread of Covid. Individuals living under restrictions were no less likely to report Covid symptoms than their counterparts on the other side of the border. This was true even for young people, and those who regularly used pubs and restaurants.
One plausible explanation for Takaku and colleagues’ findings is that people simply socialised elsewhere. Another possibility is that restrictions do not have additive effects on transmission; perhaps they only make a difference once practically all public locations are closed (including ‘essential’ ones like grocery stores and pharmacies).
“Given the large detrimental effects on employment,” the authors write, “alternative measures for full-service restaurants and bars should be considered”. And the best alternative measure, I would argue, is returning to business as usual.