Coronavirus: WHO warns against over-reliance on testing to end lockdowns

Health experts stress not enough is known about possible protection from a secondary infection

Worshippers perform taraweeh prayer in front of the Kaaba in the Grand Mosque on the first day of Ramadan in Makkah, Saudi Arabia. While the general public are not allowed to enter because of the coronavirus pandemic, imams at Islam’s holiest site still lead the daily prayers with staff and workers. AFP

Saudi policemen stand guard next to the Kaaba in Makkah's Grand Mosque on the first day of Ramadan. AFP

Muslims offer Taraweeh evening prayers on the first day of the Muslim holy month of Ramadan at a mosque in Kandahar city. AFP

Muslims offer special taraveeh prayers during the Muslim holy month of Ramadan amid lockdown due to the ongoing coronavirus COVID-19 pandemic, in Herat, Afghanistan. EPA

Sudanese men break their fast in a street in the capital Khartoum during the Muslim holy month of Ramadan amid a curfew due to the COVID-19 coronavirus pandemic. AFP

A peddlar sells bread and pastries from a cart in the rain in a square in Syria's northwestern city of Idlib on the first day of Ramadan. AFP

A Lebanese drummer (Musaharati) wears a protective mask and carries a small drum as he makes his rounds waking Muslims for Suhor, the meal taken during Ramadan before sunrise prayers, amid the coronavirus lockdown in Beirut, Lebanon, 25 April 2020. EPA

A Lebanese supporter of the Jemaah Islamiyah wears a medical mask, drives his ATV to celebrate in the first day of Ramadan in Beirut, Lebanon, 24 April 2020. EPA

Palestinian Walid al-Hattab prepares soup for the poor during the first day of Ramadan in Gaza City on April 24, 2020. AFP

A Palestinian family perform the tarawih special prayer during the first day of Ramadan in their home in Khan Yunis in the southern Gaza Strip on April 24, 2020. AFP

A Palestinian preacher speaks before a camera while recording a sermon and broadcasting the audio onto loudspeakers inside an empty mosque in the village of Salem east of Nablus in the occupied West Bank on the first day of Ramadan on April 24, 2020. AFP

A Palestinian worker prepares a lantern on the first day of Ramadan, in the west bank city of Nablus, 24 April 2020. EPA

A Yemeni collects the copies of the Koran on the first day of the Muslim holy month of Ramadan at a mosque in Sana'a, Yemen, 24 April 2020. EPA

An Iranian woman prays outside of the Saleh Shrine on the eve of the holy month of Ramadan, in Tehran, Iran, 24 April 2020. EPA

A car travels in front of closed shops, and light decorations during the first night of Ramadan, in the Cairo suburb of Maadi, Egypt, April 24, 2020. Reuters

Tunisians buy cheese on the first day of Ramadan at a market in Tunis, Tunisia, 24 April 2020. EPA

A Tunisian woman sells dates on the first day of Ramadan at a market in Tunis, Tunisia, 24 April 2020. EPA

A man walks past closed shops before the start of Ramadan in the usually bustling Medina of Rabat, Morocco, Thursday, April 23, 2020. AP Photo

The World Health Organisation has warned governments against basing their post-lockdown policies on the outcome of Covid-19 antibody test results.

Such tests are seen by some as the best hope of ending movement restrictions before the emergence of vaccines – which still remain many months away at least.

The WHO’s concern focuses on so-called “immunity passports” granted to people whose test results indicate past infection by the Covid-19 virus, and are then allowed to return to normal life.

Such schemes have been considered as a means of ending lockdowns by various countries – including the UK and United States – but have so far only been launched in Chile.

In a briefing note on April 24, the WHO warned that there was "currently no evidence that people who have recovered from Covid-19 and have antibodies are protected from a second infection".

What we don't yet know is the level of protection or how long it will last.

But in a statement on Sunday, apparently to allay "concern” about its initial remarks, the WHO made clear it was not saying that those who recover from Covid-19 have no protection against becoming infected again.

“We expect that most people who are infected with Covid-19 will develop an antibody response that will provide some level of protection," the organisation said.

"What we don't yet know is the level of protection or how long it will last.

"We are working with scientists around the world to better understand the body's response to Codid-19 infection."

Far from being a U-turn, the important clarification bridges the gap between the common perception of how the body responds to viral infections and the reality.

It is widely believed that once exposed to a virus by either infection or vaccination, the disease-fighting immune system develops antibodies that will defeat any future attack.

But the truth is far more complex. While the body can acquire long-term protection against some viruses like measles, polio and tetanus, this is not always the case.

The coronaviruses – to which the Covid-19 virus belongs – are a case in point.

Studies have shown that protection against some types declines in a matter of months, allowing people to be re-infected.

There have already been reports from China, South Korea and Japan of people who seem to have recovered from Covid-19 and then become re-infected with the virus.

Scientists have so far been cautious about such claims. The sheer speed with which the virus re-appeared has led to other explanations being put forward.

For example, such patients may never have been truly free of the disease, or their positive test results may have been false alarms.

It is also possible that – as with the coronavirus 229E responsible for colds – the patients may have become re-infected, but now pose little risk to either themselves or others.

What is clear is that there remain big gaps in the science of how the immune system deals with the Covid-19 virus.

It is also not unreasonable to suggest these unknowns could prove catastrophic for any post-lockdown policy such the immunity passport that puts misplaced faith in test results.

As the WHO statement makes clear, while most people may have some immunity following recovery from Covid-19, it is unknown how long such immunity lasts, and thus how long an immunity passport should be valid for.

Even the reliability of antibody tests remains a matter of controversy. As the WHO points out, these may be fooled by past infections with far more common coronaviruses that cause colds, and therefore wrongly indicate a previous infection with Covid-19.

As a result, people granted immunity passports could return to normal life with a false sense of security, only to fall victim again.

Even if such issues affect just a few per cent of people, the consequences could be dire when rolled out across an entire nation, overwhelming its health-care system.

There is also concern that the value of having an immunity passport could lead to corruption and faked test results.

According to the WHO: “At this point in the pandemic, there is not enough evidence about the effectiveness of antibody-mediated immunity to guarantee the accuracy of an “immunity passport” or “risk-free certificate.””

In the meantime, the scientific consensus remains that there are no short cuts to permanently lifting lockdowns.

Robert Matthews is Visiting Professor of Science at Aston University, Birmingham, UK