FRANKFURT, Germany (AP) — A key indicator of German business optimism unexpectedly ticked up in February despite concerns about how the spread of the coronavirus might affect the economy through key trade partner China.

The Ifo institute index crept up to 96.1 points from 96.0 in January, the third increase in the last four months. Economists, however, cautioned that some survey responses may have come in earlier in February, when concerns were lower and that troubles from the outbreak could still hit German manufacturers.

Economist Andreas Rees at UniCredit bank said the reading “at first sight… seems to be a pleasant surprise” but warned that it is not clear whether the February data already contain the latest developments to the full extent.

He said next month’s survey might provide a clearer sense of the impact of the virus and the associated COVID-19 illness.