By Victoria Waldersee

LISBON (Reuters) – As Portugal prepares to ease its coronavirus lockdown, a number of cities and research organisations are rolling out antibody tests even though national authorities warn it may be too early to draw conclusions on immunity among the population as a whole.

Some countries see antibody tests as a way to determine if people have developed immunity through exposure to the coronavirus, potentially allowing them to return to work. But virology experts are not yet certain what immunity such antibodies might provide.

“We can have antibodies after 15 days but they may not protect us. When we know more about these tests, they will be very useful,” says Gra├ža Freitas, head of Portugal’s health directorate DGS.

Experts say Portugal was the last country in Western Europe to report a confirmed case of the coronavirus – on March 2 – meaning the virus is not yet widespread enough for mass testing to be worthwhile.

The country has reported 20,863 confirmed cases and 735 deaths, much less than Spain.

Portugal hopes to gradually relax restrictions on schools, stores and cultural spaces from next month.

In a letter, 167 doctors, business and union leaders last week called on the government to launch widespread antibody tests and contact tracing to allow the lockdown to be lifted faster.

Some city councils have bought antibody tests from private labs for use on their populations or in nursing homes and on frontline staff as a substitute for testing for the virus itself. Cascais near Lisbon on Thursday began tests which it said would cover 400 people.

The Champalimaud Foundation for biomedical research is working with the Order of Nurses to test 667 nurses and auxiliary staff this week in Lisbon and Porto, using German-made tests, a foundation spokesperson said.

A consortium of research institutes at the University of Lisbon, Nova University of Lisbon and the Gulbenkian Science Institute hopes to mass-produce inexpensive tests by the end of next week, Gulbenkian director Monica Bettencourt-Dias said.

The Ricardo Jorge National Institute of Health aims to launch a pilot antibody testing project on a sample of 1,700 people in the coming weeks. It is also evaluating a method of curing seriously ill patients through infusing blood plasma from people who have recovered.

(Reporting by Victoria Waldersee; Editing by Andrei Khalip and Giles Elgood)

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