TEHRAN (Press Shia) – People may only be immune to coronaviruses for six months, a study said, raising questions over whether ‘immunity passports’ could be a route out of lockdown.

Researchers from the University of Amsterdam tested 10 men for four coronaviruses regularly over the course of 35 years.

The four coronaviruses cause the common cold and research said there was ‘an alarmingly short duration of protective immunity’, Times reported.

They said that after 12 months, people were frequently reinfected with the virus and after six months the levels of antibodies substantially reduced.

Health Secretary Matt Hancock announced at the Downing Street briefing on Thursday that the Government has signed a contract for 10 million antibody testing kits.

He stressed the science of how people develop immunity and how long it lasts was still emerging.

He confirmed that ministers are already looking at a ‘system of certification’ that would signify people who are safe to go back to work and mix freely with others.

The University of Amsterdam researchers said that antibody tests to estimate how many people had been infected would become of limited use.

It comes as Oxford University began recruiting for large-scale trials for their coronavirus vaccine.

The study suggests people may have to get the jab annually to be immune to the bug.

The study has not yet been peer-reviewed and did not include women.

Professor Lia van der Hoek, one of the researchers involved in the study told The Times: ‘Herd immunity is an issue, even with vaccination, as it may be that people can get an infection again within six to 12 months. It is, however, uncertain what kind of disease is associated with a reinfection by Sars-CoV-2, that is of course a big uncertainty.’

Virologist at Reading University Ian Jones added that other research suggest longer-lasting immunity as some only cause a mild disease which might not trigger great immunity.

He added that if the protection was partial it would be hard to score.

Hancock said: ‘We’re developing this critical science to know the impact of a positive antibody test and to develop the systems of certification to ensure people who have positive antibodies can be given assurances of what they can safely do.’

He added: ‘We’re not yet in a position to say that those who test positive in these antibody tests are immune from coronavirus.

‘But as our understanding of the disease improves, the insight these antibody tests provide will be crucial.’