The world needs to become more judicious about how it uses Covid-19 tests because there still aren’t enough to go around, according to one of the biggest diagnostics manufacturers.

Demand for tests is higher than the industry can supply and that may continue for months, Severin Schwan, the chief executive officer of Roche Holding AG, warned Thursday. That’s even after Roche quadrupled its capacity to churn out various types of coronavirus tests.

“Demand is enormous and therefore it is so important that tests are really allocated to those patients with signs and symptoms, patients who are most in need,” Schwan told Bloomberg TV in an interview. Molecular tests that determine whether a patient has the virus are most scarce, he said.

Some governments have sent military planes to pick up testing components, according to Thomas Schinecker, who heads Roche’s diagnostics unit.

Sales of coronavirus tests helped buoy the Swiss drugmaker’s results in the first half, but plunging revenue in May still led the company to report disappointing results as lockdowns held back some key medicines such as Ocrevus for multiple sclerosis. The stock fell as much as 1.6% in Zurich.

Roche in its half-year report pointed to a rebound in demand in June and reiterated its outlook for the year. The company’s diagnostics unit has until rolled out some of the earliest and most-accurate molecular and antibody tests for Covid-19, but use of other testing products suffered due to disruptions from the pandemic.

Sales of Actemra, a rheumatoid arthritis medicines, were boosted by demand for coronavirus patients amid evidence it may help against the new virus. Results from a formal clinical trial of the drug on patients with severe pneumonia will be released soon, the company said.

This story provided by Bloomberg News.