Samples could be processed daily all over the world, furnishing a live map of viral immunity
Samples could be processed daily all over the world, furnishing a live map of viral immunity © Bay Ismoyo/AFP/Getty

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The writer is a science commentator

About three years ago, Princeton graduate student Amy Winter had an inspired idea. Children in Madagascar who turn up in clinics with a fever and rash usually have their blood taken to check for short-term infections like measles or rubella. Why not use those same blood samples to piece together a picture of immunity, rather than current infection?

In June 2018, Ms Winter and colleagues reported in the American Journal of Epidemiology that their “serosurvey” revealed a lower level of measles immunity than the WHO advocates, and concluded “that Madagascar is at risk of a serious measles outbreak”. The outbreak duly arrived that September, mushrooming into an epidemic infecting more than 100,000 people and killing around 1,200.

Now researchers are pushing for a programme of comprehensive immunity sampling to be rolled out across the world. A so-called Global Immunological Observatory would regularly monitor antibody data garnered from blood and saliva to build up a real-time atlas of “normal” immunity and, as with measles in Madagascar, predict the emergence of known and unknown diseases.

Had such a system been in place in the US in January, its supporters claim, it might have offered early clues that a new coronavirus was circulating and prompted faster shutdowns. “If we had been pulling in blood from Seattle and other places where early cases were detected, we could have figured that we were getting a lot more ‘hits’ in terms of antibody responses to coronaviruses,” says Jessica Metcalf, a demographer and infectious diseases biologist at Princeton University in New Jersey who co-authored a paper on the GIO in June. She supervised Ms Winter’s research conducted with the Institut Pasteur, Madagascar’s national testing laboratory.

Some early “hits”’ would have arisen because of previous encounters with milder, seasonal coronaviruses. The immune system is likely to have recognised a structurally similar viral invader and launched a response. “Detecting an anomaly [in baseline immunity] might only have bought us a week or so but this pandemic has shown that every week counts,” Prof Metcalf adds. Michael Mina, an immunologist at the Harvard School of Public Health and a co-author of the paper, told the journal Science that the blood of New Yorkers might even have yielded enough information for governor Andrew Cuomo to shut down the state two weeks earlier.

Advances in sampling technology mean a tiny drop of blood can be applied to a chip containing epitopes — distinctive fragments recognisable by the immune system — of the 200-plus viruses known to infect humans. The chip reveals which antibodies are present. Thousands of anonymised blood samples could be processed daily all over the world, furnishing a live map of viral immunity. That could be linked to a global pathogen observatory to identify whether new viruses have swirled into human circulation.

Sampling across thousands of locations over time makes for more fine-grained surveillance — essential, she says, as pandemics often spring surprises. The 2009 swine flu pandemic originated in Mexico, not usually a viral hotspot; the Zika virus, identified in 1947, was thought relatively benign until the 2015 epidemic saw it linked to foetal abnormalities.

Prof Metcalf first suggested a similar effort, a World Serology Bank, with colleagues in 2016. That focused on blood; information on immunity can also be gleaned from saliva and urine.

The idea of a global observatory, its data freely available to all, might not have stirred the blood first time round. But, encouragingly, philanthropists are now expressing interest; a pilot study is under way at Harvard. As the world seeks to head off future pandemics, it surely deserves reviving.

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