There is an “urgent need” for better quality studies assessing the effectiveness of Covid-19 antibody tests, experts have said.

Researchers said caution is “warranted” if using antibody tests for clinical decision-making or surveillance in the population.

The examination, published in The BMJ, looked at evidence on tests published before April 30.

Antibody tests – also known as serological tests – look for antibodies in a person’s blood.

This says whether they have had an illness in the past.

An international team of researchers, led by academics from the McGill University Health Centre in Montreal, Canada, examined data on all studies which measured the sensitivity and specificity of Covid-19 antibody tests.

The authors examined 40 studies and raised concerns over “important weaknesses” in the evidence behind the tests.

They said that many of the studies were not peer-reviewed and most were found to have a high or unclear risk of bias.

When sensitivity results for each study were pooled together, they ranged from 66% to 97.8% – depending on the type of test method used – which means that between 2.2% and 34% of patients with Covid-19 would be missed under the tests involved in this study.

Pooled specificities ranged from 96.6% to 99.7%, depending on the test method, meaning that between 3.4% and 0.3% of patients would be wrongly identified as having Covid-19.

“Higher quality clinical studies assessing the diagnostic accuracy of serological tests for Covid-19 are urgently needed,” the authors wrote.

But academics commenting on the study stressed that the findings were from studies published until the end of April – so more recent studies may have better design – and that many tests improve with time.

Meanwhile, a separate opinion piece published in the journal calls for more patient and public input into Covid-19 policy making.

The BMJ’s patient partnership editor Tessa Richards and patient editor Henry Sowcroft argue that it was “regrettable” that patients, families, and frontline health and social care professionals were not involved in decision making.

“Their input would have helped to mitigate the predictable adverse effects of massive service reconfiguration and lockdown, and emphasised the need for clarity on which services would be suspended and which would remain accessible.”