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expert reaction to WHO clarification of their statement on 26/04/20 about immunity passports

The WHO has made statements and clarified their position on COVID-19 immunity passports and antibody tests. 


Professor Sylvia Richardson, MRC Biostatistics Unit, President Elect Royal Statistical Society, on behalf of the RSS Covid-19 Task Force

“The Royal Statistical Society Covid-19 Task Force urges caution with early claims about the performance of new biomarker tests for COVID-19,”

“Unlike drugs, new tests undergo no scrutiny before they can be CE-marked* and marketed, and it is important that we take time to see complete rigorous evaluations in clinical practice of new tests before they are purchased (unless return-able) and distributed for use.   We have already seen evidence that performance claims made by test manufacturers (which are often based on unrealistic laboratory studies) do not deliver when tests are used in clinical practice.   With high profits to be made from bulk purchases of tests, it is wise to ensure that rigorous studies are undertaken by independent groups, and that all studies are prospectively registered, protocols published and full reports made available to allow public and scientific scrutiny.”

*The CE marking is the manufacturer’s declaration that the product meets EU standards for health, safety, and environmental protection.


Dr Jeremy Rossman, Honorary Senior Lecturer in Virology at the University of Kent, said:

“The WHO have recently warned that there is no evidence that people who have been infected with SARS-CoV-2 will be immune to a subsequent infection. This posting was then retracted to avoid confusion as it seems to imply that people don’t become immune to subsequent infections. The message is that we just don’t know enough at present to say if people that recover will be immune or not. We know that the virus causes a robust immune activation, we know that survivors do generate antibodies to the virus but we don’t yet know if generates an immune memory that protects against re-infection, we don’t know what percentage of people will be protected and we don’t know how long this protection would last.”


Prof James Naismith, Rosalind Franklin Institute and University of Oxford, said:

“It seems certain that almost all people who have been infected will have complete immunity against re-infection for at least a short time.

“We know that for many coronaviruses, immunity weakens in many people over a few years, and for this reason some viruses infect and re-infect people. We do not (and cannot) know for sure how COVID-19 will behave.

“So-called ‘immunity passports’ for previously infected people are political inventions built around complex scientific concepts. Only a safe and effective vaccine, that I believe will come in the future, will deliver widespread immunity from infection.

“As things stand today there are two (and only two) proven ways to reduce the burden of infection at our disposal: strict social distancing; and test, trace, isolate with mild social distancing. Almost the entire world has had to rely on ‘lockdown’, but this is unbearable over the longer term. Therefore, the UK and other countries should get on with setting up test, trace and isolate with a tolerable level of social distancing as quickly as possible. This means rapid testing, almost instant tracing that does not shred civil liberties and isolation that is effective yet compassionate. South Korea did not invent their system overnight; it is arrogant to pretend that somehow we can and it is disingenuous to state the UK was alone in being unable to deploy this approach. It can be done but it takes time and requires a laser focus on each aspect for it to succeed.

“We can play an important part: the more effectively we practise social distancing at the moment, the faster the infections will drop and the sooner that test, trace, isolate will become viable. “


Prof Francois Balloux, Professor of Computational Systems Biology and Director of UCL Genetics Institute, University College London (UCL), said:

“There is no uncontroversial evidence for reinfection by COVID-19 at this stage. We do not know yet for how long someone infected will be immunised against subsequent infection, though on average it should be for a year or more. Importantly, even if residual immunity is insufficient to protect from re-infection, it is still expected to lead to milder symptoms upon secondary infection.

“The confusion about immunity in the context of ‘immunity passports’ comes mostly from the observation that some patients do not mount a strong antigenic response. As such, despite having been infected, they may not test positive when diagnosed with serological tests. Whether these patients are susceptible to reinfection remains unknown since immunity may still be conferred by other immunological pathways (T-cell immunity).”


Dr Tom Wingfield, Senior Clinical Lecturer and Honorary Consultant Physician, Liverpool School of Tropical Medicine, said:

“Antibody tests measure the amount of antibody produced against a specific infection. People who were infected with other coronaviruses like SARS and MERS produced antibodies against these illnesses following infection, for up to three years in some cases. However, it is not clear whether the presence of these antibodies means that a person is immune to a repeat infection.

“Antibody tests for SARS-CoV-2, the novel coronavirus that causes Covid-19, are currently being developed but we haven’t yet fully characterised the immune response to SARS-CoV-2. There remain many unknowns. These include how long SARS-CoV-2 antibodies will last following infection and whether having these antibodies means that a person is immune to further SARS-CoV-2 infection. 

“In short, we don’t yet have enough evidence to show that people who have had Covid-19 will be immune to future Covid-19 illness. There are multiple studies ongoing here in Liverpool ( and across the UK and beyond, which are looking to answer these questions.”


Prof Babak Javid, Principal Investigator, Tsinghua University School of Medicine, Beijing, and Consultant in infectious diseases at Cambridge University Hospitals, said:

“The initial WHO statement was very confusing and highlights how technically precise language such as ‘no evidence to support’ can have very different meanings to scientists and the general public.  In the clarification, the WHO acknowledges that although it is true that we just don’t know whether natural infection provides long-lasting immunity, or to what degree of protection (i.e. ‘no evidence’), this does NOT mean they do not expect some degree of immunity to be afforded by natural infection, quite the opposite.

“In fact, we know from experiments performed in the UK in the 1970s and 1980s that there is immunity to common-cold coronaviruses, that this immunity is highly correlated with antibody responses, and that the immunity is not long-lasting.  So given that we know that the majority of people that have had COVID-19 develop neutralising antibody responses, it is reasonable to assume that they will develop at least short-term immunity from re-infection.  The critical questions are how robust that immunity would be, and for how long it would last.  These questions can be reasonably addressed by performing longitudinal studies in people known to have been infected: i.e. test their antibody responses over time, especially if they are in high-risk groups (such as healthcare workers); and monitor whether antibodies are associated with protection from re-infection in the light of an ongoing pandemic.”

“On a more general note, the high degree of anxiety provoked by the WHO’s message, and their rapid correction of their intended meaning emphasises the need for scientists and science organisations not to hide behind precise terms that may be misleading to a general audience.”


Dr Simon Clarke, Associate Professor in Cellular Microbiology, University of Reading, said:

“It’s reasonable to expect that some of the immune response generated during an episode of CoViD-19 will persist for some time after the infection has been resolved, giving protection against re-infection.  At this stage nobody knows for sure whether this is indeed the case or for how long it will protect someone, it could be weeks, months or years and it would be unwise to make predictions that are not based on any evidence.  It’s worth remembering that we’ve only known about this disease for about 4 months, so cannot at this stage have any knowledge about whether immunity lasts beyond this rather limited time frame.”


 Prof Will Irving, Professor of Virology, University of Nottingham, said:

“The immune response to any virus infection has several components – the body will respond to all the foreign material in the virus. Some of those responses will be directed at a part of the virus which will prevent the virus from infecting target cells (for instance neutralising antibodies), but other responses may not be neutralising.

“Testing for antibodies by most technologies will not distinguish between neutralising and non-neutralising antibodies, nor will it give information about other aspects of the immune response (such as T cells). Thus, merely finding that someone has antibodies to the virus does not necessarily indicate that that individual has protective immunity. They may have – and I think it is in the area of correlating antibody presence with protection that we need more data.”


Prof Paul Hunter, Professor in Medicine, UEA, said:

“The latest tweet from WHO is a correct statement of the situation. It is fair to say that almost everybody/everybody who recovers from COVID-19 will have developed immunity otherwise they would not have recovered. There may be particular issues in very immune-suppressed people such as people who have had liver or kidney transplants. What we do not know is how long that immunity will last. It almost certainly will not last for life. Based on antibody studies in SARS it is possible that immunity will only last about 1 to 2 years, though this is not yet known for certain and we do not know how good blood antibody levels are in predicting immunity for COVID-19.

“However, immunity to an infectious virus is not necessarily all or nothing. It is possible that people who do get an early re-infection will have a less severe illness then their primary infection because of some residual immunity even when that is not sufficient to prevent re-infection. It is not known whether these people will be as infectious as during their first infection, though it is certainly plausible that they will be less infectious.”


All our previous output on this subject can be seen at this weblink:


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