By Daina Beth Solomon

MEXICO CITY (Reuters) – Mexico’s capital registered 8,072 more deaths in the first five months this year than the average from the same period over the past four years, an analysis by independent researchers showed on Monday, suggesting a possible surge due to the coronavirus.

Health officials have reported 1,655 deaths from the virus in Mexico City, out of 7,394 deaths nationwide. They have also acknowledged that the true death toll is higher, but difficult to estimate due to a low testing rate.

Software developer Mario Romero Zavala and economic consultant Laurianne Despeghel, whose analysis was published in Mexican magazine Nexos, tallied 39,173 fatalities this year through May 20 by extracting data from Mexico City’s online database of death certificates.

Over the prior four years, they calculated just 31,101 deaths on average during the same period, using the same database.

Mexico City’s official count of deaths from the coronavirus represents just over 20% of the study’s “excess mortality” – a term used by epidemiologists to estimate the increase in deaths, versus normal conditions, attributable to a public health crisis.

Excess mortality is difficult to calculate in Mexico because the most recent data on fatalities from the national statistics institute is from 2018.

Despeghel said the analysis was only a first step to measuring the virus’ impact.

“While studying excess deaths allows us to identify a higher mortality rate during the COVID-19 crisis, it is not sufficient to attribute it directly or solely to the virus,” she said.

A Reuters review of data from 13 funeral homes in Mexico City showed that the excess mortality rate in the first week of May could be at least 2.5 times higher than the government’s tally of deaths from the coronavirus during that period.

(Reporting by Daina Beth Solomon; editing by Diane Craft)