One in three Russian doctors who treat coronavirus patients have been told to change how they report cases, according to a survey cited by the Meduza news website Thursday amid questions over Russia’s low Covid-19 death toll.

The survey on the Russian app “Doctor’s Handbook” involved 509 medics, Meduza reported.

More than one-third of the respondents said they had been instructed to label pneumonia caused by Covid-19 as a different disease.

“This practice lets one adjust the incidence and mortality rates,” the outlet wrote.

Russia has the world’s second-highest number of coronavirus cases with 326,448 as of Thursday, and a death rate of 1.88 per 100,000 Russians. In the United States, that figure is 27.61 per 100,000 Americans, while Britain’s death rate sits at 52.45 per 100,000 people.

Moscow civil registry data showed 18% more fatalities in April 2020 than the average April mortality total over the past decade. Facing the suggestion that the excess deaths could be linked to Covid-19, city health officials said 60% of its coronavirus patients died from vascular accidents, malignant diseases, organ failure and incurable deadly diseases.

Authorities have denied under-reporting the numbers, saying that Russia was able to learn lessons from the experiences of western Europe since the pandemic came later to Russia. 

Russia counts deaths of coronavirus-positive patients toward its total if pathologists say the virus directly caused their deaths.