A four-month-old girl has died from coronavirus after being infected by a relative.
She has become the first person under the age of 10 to be killed by the virus in her country.
Portuguese authorities say the country is also facing a series of worrying spikes in homes for the elderly.
In a press conference, the Portuguese Health Minister, Marta Temido, said that the infant girl had a serious congenital heart disease and died in the Lisbon area having been infected with coronavirus by a relative.
The Director General of the health service, Graca Freitas, said the girl caught the virus through "family transmission," and had a very serious underlying health condition.
She added: "She was born with very severe congenital heart disease and the COVID situation led to the worsening of this pathology and the appearance of a cardiac consequence called myocarditis.”
Myocarditis is an inflammation of the myocardial muscle tissue, a condition that can be caused by an infection.
The death was caused by "septic shock", added Freitas, but "was reported as [being caused by] Covid-19" according to the standards laid out by the World Health Organization.
It was one of the two deaths registered in the last 24 hours in Portugal, with 253 new infections having been recorded.
Both deaths occurred in the Lisbon and Tagus region, the focal point of the current spikes.
The baby's name has not been revealed.
