COVID-19 tests

Preliminary results showing that a cheap steroid reduces the risk of death among gravely ill COIVD-19 patients is inspiring hope and skepticism.

The finding has not been peer-reviewed, but University of Oxford researchers announced the steroid dexamethasone—when given to patients on ventilators for up to 10 days—cut the risk of death by a third, CNN reports.

The risk of death for patients on oxygen but not on ventilators was reduced by a fifth, but the steroid made no difference among patients who didn’t require either.

But:

Serology testing for SARS-CoV-2 is at increased demand in order to better quantify the number of cases of COVID-19, including those that may be asymptomatic or have recovered. Serology tests are blood-based tests that can be used to identify whether people have been exposed to a particular pathogen by looking at their immune response. In contrast, the RT-PCR tests currently being used globally to diagnose cases of COVID-19 can only indicate the presence of viral material during infection and will not indicate if a person was infected and subsequently recovered. These tests can give greater detail into the prevalence of a disease in a population by identifying individuals who have developed antibodies to the virus.

No therapy, no vaccine. At least, COVID-19 survivors can be tested for antibodies and know they’re immune, right?

Wrong.

WHO threw cold water on that assumption on Friday, saying there’s no evidence that if you’ve survived COVID-19, you have immunity, according to the Irish Times. Tests may reveal the presence of antibodies, but that doesn’t mean you’re safe from reinfection, said WHO’s Maria van Kerchief.

When it comes to COVID-19 testing in the United States, the situation is about as messy as it gets.

The U.S. went from having no tests, or assays, available for COVID-19 diagnostics to having multiple different tests available in a span of just a few weeks. Today more than 230 test developers have alerted the Food and Drug Administration that they are requesting emergency authorization for their tests; 20 have been granted. And 110 laboratories around the country, including my own, are also using their own tests. Having this number of diagnostic tests available to detect a single virus in such a short time frame is unprecedented.

Countries that adopted a test, track and treat approach gained an early edge against COVID-19.

Germany jumped to develop a test by January—which, combined with its ample intensive care beds and early embrace of social distancing—could explain why it's seeing fewer deaths than its neighbors, according to the AP. Germany reports 775 deaths and 71,000 cases; compare that to Italy’s 12,400 deaths for 106,000 cases and Spain’s 9,000+ deaths­­­­­­­­­­­­­ and 102,000 cases.

With much of society now effectively in lockdown, how will we know when it’s safe to resume something like normality?

It will largely depend on being able to say who is safe from contracting the coronavirus, officially named SARS-CoV-2, which causes the disease called COVID-19, and who still needs to stay out of harm’s way. A blood test to detect who has antibodies against the virus would be a crucial aid.

An antibody test – which would identify those whose immune systems have already encountered the virus, as opposed to current tests that reveal the presence of the virus itself – will be an important part of efforts to track the true extent of the outbreak.