Newborn triplets in Mexico have COVID-19, their parents do not

Mexican health authorities are trying to understand how a set of newborn triplets became infected with the novel coronavirus even though neither one of their parents tested positive for the virus.

Health authorities called the case "unheard of."

The triplets, a girl and two boys, were tested four hours after being born about six weeks earlylast week in the central state San Luis Potosi, health authorities said. State Health Secretary Dr. Monica Liliana Rangel Martinez told reporters that it is protocol to test all premature babies for the virus.

Initially, health authorities said the mother was believed to be an asymptomatic carrier of the virus. But her tests later showed that neither she nor the father were infected.

"The parents' results are negative, which catches our attention," Martinez said during a news conference on Tuesday.

"We specifically requested since yesterday ... that a group of experts investigates the case."

Two of the babies born on June 17 are in good health and show no symptoms of COVID-19, doctors treating the triplets said, while the third has pneumonia but is in stable condition.

Rangel said the triplets will remain hospitalized and under observation.

Mexico has reported more than 191,000 coronavirus cases and 23,377deaths, according to the global tracking dashboard being kept by Johns Hopkins University.