A recent study conducted by Stanford Medicine researchers has shown that platelet-rich plasma injections may be effective in treating long-term smell loss caused by COVID-19. The trial involved 26 participants who had been suffering from this condition for between six and twelve months, and had already tried other treatments. Half of the participants received platelet-rich plasma injections into their nasal cavity every two weeks for six weeks, while the other half received placebo injections of saline.
The researchers assessed smell ability using a standard olfactory test, Sniffin’ Sticks, and found that the participants who received the platelet-rich plasma injections were 12.5 times more likely to improve than those who received the placebo. Three months after their first injection, the platelet-rich plasma group scored on average 6.25 points higher than before treatment, which was 3.67 points greater than the placebo group. 57.1% of the platelet-rich plasma group had shown a clinically significant improvement, compared with just 8.3% in the placebo group.
These results suggest that platelet-rich plasma injections may be an effective treatment for long-term, COVID-19-related smell loss. The researchers are now offering platelet-rich plasma injections to patients outside the trial and further studies are needed to better understand the effectiveness of this treatment.