Many Catholic worshippers in Naples, Italy, have expressed concern after the blood of San Gennaro, the patron of Naples, failed to liquefy despite several hours of prayer. 

A vial of dried blood belonging to the fourth-century saint is put on display at city's cathedral three times a year, with the faithful praying for it to turn into liquid -  a ritual known as the “Miracle of San Gennaro”. 

However, despite hours of praying in the morning and a special Mass on Wednesday afternoon, the blood failed to become liquid, which many viewed as a bad omen for the future.

“When we took the reliquary from the safe, the blood was absolutely solid and remains absolutely solid,” Fr. Vincenzo de Gregorio, abbot of the Chapel of St. Januarius in Naples Cathedral, told the Catholic News Agency. 

On occasion, the ampoule of blood has been discovered already liquefied when it is removed from the Naples bank vault in which it is stored.

When the blood appeared to remain solid as the day wore on, Gregorio still insisted there was no need to panic. “It’s alright, we will await the sign with faith," he said. 

By the end of mass, however, the blood had still not liquefied, prompting concerns from some of the congregation. Many of the faithful recall an incident in 1980 when a massive earthquake struck southern Italy just two months later after they prayed unsuccessfully for the blood to liquefy - more than 3,000 people perished in the natural disaster. 

However, a Vatican journalist, Francesco Antonio Grana, told CNA that the liquefaction “almost never” happens on December 16. The saint's blood liquefied in May and September of this year, according to Cardinal Sepe, the Archbishop of Naples.

In 2015, Pope Francis prayed for the liquefaction to occur, becoming the first sitting pope to do so since 1848. After the blood liquefied and then dried up again, Francis joked: "It seems that the saint loves us a little bit. We have to convert a little more for him to love us completely."