WHO Asserts There is No Evidence SARS-CoV-2 is Becoming Less Severe

Experts from the World Health Organization (WHO), including epidemiologist Maria Van Kerkhove, PhD, the group’s COVID-19 technical lead, have denounced claims made by Alberto Zangrillo, MD, an Italian clinician who suggested that the coronavirus has been losing potency.

Dr. Zangrillo is head of intensive care at the San Raffaele Hospital in Lombardy, which was heavily affected by the epidemic. He gained attention in late May after telling Italian television reporters that new data showed the coronavirus’ viral load was weakening.

“The swabs that were performed over the last 10 days showed a viral load in quantitative terms that was absolutely infinitesimal compared to the ones carried out on patients a month or two ago,” he told reporters, citing a study by Massimo Clementi, MD, director of the Microbiology and Virology Laboratory at the San Raffaele Hospital in Milan. The study, which is set to be published in the coming weeks, compared viral samples from patients with COVID-19 at the hospital in March with samples from May.

WHO scientists and other experts immediately spoke out about Dr. Zangrillo’s claims, arguing there is no conclusive data to prove the virus is changing significantly.

“In terms of transmissibility, that has not changed, in terms of severity, that has not changed,” said Dr. Van Kerkhove said during a news conference.

It is not unusual for viruses to mutate, but according to Martin Hibberd, PhD, Professor of Emerging Infectious Diseases at the London School of Hygiene & Tropical Medicine, current studies looking at genetic changes in SARS-CoV-2 did not support the claim that the virus was becoming less potent.

Professor Zangrillo later clarified his original comment to Reuters: “We have never said that the virus has changed, we said that the interaction between the virus and the host has definitely changed.” He said the change in viral load he noticed could be due to new characteristics of the virus, which have not been identified, or changes in the infected population.

Sources: Reuters, June 2, 2020; The Hill, June 2, 2020.