Should postmortem testing for SARS-CoV-2 be performed in all donors of ocular tissues?
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Tests recommended in Italy but may be misleading
When the COVID-19 outbreak started in Italy, new guidelines for tissue and cell donation were promptly issued.
In accordance with these recommendations, in all Italian eye banks, we perform a careful medical anamnesis to exclude donors with premortem clinical symptoms compatible with COVID-19, followed by postmortem nasopharyngeal swab for all donors classified as eligible. Such a strict protocol, aimed at providing a COVID-19-free route to corneal transplantation, was based on the precautionary principle rather than scientific evidence, which at the time we did not have. It certainly guarantees the highest possible protection from the risk for transmission, maximizing safety. We have had no case of COVID-19 transmission from donor to recipient, but it is also true that no case has been reported worldwide, and we now have convincing evidence that even positive corneas are unlikely to transmit the virus to recipients.
From Feb. 24, 2020, when the guidelines were issued, to March 30, 2021, we have performed 2,326 postmortem swabs in our eye bank. Overall, 35 (1.5%) were positive for SARS-CoV-2. We performed further analysis and found that SARS-CoV-2 RNA was present in only four of 69 corneas from those positive donors, and in no case the RNA had the characteristics of infectious virus. Noninfectious RNA traces can still be detected weeks after the clearance of infectious virus, but they simply mean that the virus has passed. My fingerprints are not me, and if I leave them in a room, they do not mean I am still there.
Getting back to our 35 positive donors, the results of the swab triggered the protocols of contact tracing, isolation and surveillance that are prescribed in these cases. If 1.5% may seem a small percentage, the consequences were not negligible. There are going to be many such cases due to the increasing number of donors who have had COVID-19 and recovered. Current data from the thousands of cases on which laboratory studies have been performed show that already 9 days after the onset of COVID-19, patients no longer transmit the disease to others, but traces of the virus persist in the body for a long time, from 80 days in the upper respiratory tract to 4 months in the feces.
Based on the knowledge we have gained, performing postmortem swabs on all donors may be unnecessary and misleading. Taking into account that we are going to have more and more people who have had COVID-19 and recovered and who have been vaccinated, I expect that test outcomes will be extremely confusing and lead to a lot of unnecessary trouble and epidemiological alarm.
Diego Ponzin, MD, is medical director of Veneto Eye Bank, Venice, Italy.
Tests not required in US
In the United States, regulations at the federal level do not require us to perform postmortem COVID tests to screen asymptomatic cell and tissue donors. On the other hand, the Eye Bank Association of America has issued stringent guidelines on medical and social screening, and if something suspicious for COVID-19 positivity is found, the donor tissue is deferred.
One year ago, we had to reject a lot of tissue, but now more than 1 year into the pandemic, we find that most donors have had recent COVID testing performed, either in the hospital before they passed away or in the emergency room in case of emergency room death. There are still cases for which we are unable to collect sufficient history from the family and next of kin, and maybe in these cases we should consider postmortem testing. Following a new recent mandate in New York City, donors who fall under the jurisdiction of the medical examiner due to suspicious or unusual death are tested postmortem.
The FDA does not recommend postmortem testing because it has not yet been validated as a procedure. However, research is ongoing, and time will tell how postmortem compares with premortem testing.
At this point — and this is the benefit of 1 year having passed by — we are more confident and comfortable with our choices. Earlier on, if there was anything that made coronavirus infection remotely possible, we just deferred the donors, but at that time, surgery numbers were low, first due to executive mandate and later due to patient fear. Now most patients have had a COVID swab, and we still defer suspicious cases if we are unable to get enough history. I do not think we are losing a lot of tissue from not performing postmortem swabs, and I do not think we are increasing the risk for infection either.
I think that transmission through corneal transplantation is unlikely. This virus has surprised us in many ways, so I am prepared for new surprises, but the research done at the Veneto Eye Bank in Italy about viral RNA in the cornea is reassuring.
Michelle K. Rhee, MD, is medical director of the Eye-Bank for Sight Restoration, New York, and associate professor at New York Eye and Ear Infirmary of Mount Sinai.
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