Newly published figures show deaths linked to the new coronavirus in the U.K. have far exceeded preliminary estimates, adding to a growing body of evidence across Europe that closely watched daily death tallies don’t reveal the virus’s true toll.

Behind the discrepancy are lags in recording some deaths that can stretch to a week or more, as well as deaths in nursing homes and other non-hospital settings that aren’t normally captured by rapid-fire estimates used to track the pandemic.

Similar issues have complicated efforts to get an accurate read in France, Spain and Italy. The fog risks clouding tricky judgments facing officials about when the outbreak has peaked and restrictions on work and travel can be eased, while also fueling some suspicion that governments are lowballing the death count.

In the U.S., the Centers for Disease Control and Prevention warns on its website that its provisional fatality estimates for Covid-19, the disease caused by the virus, are likely to change, as the numbers are continually revised. Some fatalities can take weeks to be recorded in a nationwide database, the CDC says.

New York City on Tuesday added nearly 3,800 people to its estimate of Covid-19-linked deaths to total more than 10,000, including people who were presumed to have had the virus but weren’t tested for it before death.