THIS will be the Year of the Vaccine. That is a good deal better than 2020, which was unambiguously the Year of the Virus. That said, a great deal of caution is still required as we look forward. The pandemic is not over. The Black Death offers a cautionary tale on that.

By the end of 1349, most people in England assumed that what they called the Great Mortality was over. The plague had arrived from the Continent the summer before. It had struck capriciously, wiping out some places entirely and bypassing others, but, after 18 months, it was not over, as people assumed. A second wave followed — and then a third, fourth, and fifth. In total, between one third and a half of the population died.

To the medieval mind, the plague was a punishment from God. The second and subsequent waves came, suggested John of Reading, a monk at Westminster Abbey, writing in the 1360s, because people had returned to their sinful ways after the first wave — “their greed, scorn, and malice were asking to be punished.” That mind-set remains with us. Covid-19, some ecologists have said, is the retribution of the planet on humankind, which has grievously damaged biodiversity, creating the conditions for viruses to jump species.

Medieval folk, of course, had no vaccine and no understanding of the true cause of the infection. Later centuries decided that plague was caused by fleas leaping to humans from dead rats. But the latest archaeological and epidemiological research suggests that the Black Death, too, may have been caused by a virus, since it spread too quickly to be transmitted by fleas. But certainly the only medieval methods to fight the pandemic were processions, penance, and prayer, some barefoot flagellants combining all three.

We are luckier in that we have a vaccine — or, rather, a number of vaccines in various stages of trial, authorisation, and manufacture. Half a million of our elderly have already been inoculated. At the present rate of progress, all the most vulnerable members of the population should be vaccinated by April or May.

Yet we cannot be sanguine. Despite the ingenuity of modern science, the predicted end-date for the pandemic has become a notoriously moveable feast. It would all be over, figures of authority have progressively told us, by the summer, by Christmas, by Easter, by the end of the year. Worse still, the virus is fighting back. The new British strain of Covid is 70 per cent more infectious than the old. Another, more dangerous, strain has emerged in South Africa, and a few individuals have already brought it to Britain.

We may now not need the processions (although there are some who still feel the need to take to the streets to protest at some aspect or other of the official response to the pandemic). But we certainly need the penitence; whether or not Covid is linked in some way to human despoliation of the environment, we will not survive without a radical reordering of our attitudes to anthropocene heating of the planet.

And, if we are to win the race between the rapidly mutating virus and the logistical challenge of vaccinating enough of the population to create herd immunity, then prayer may be in order, too.