A LEADING professor has said it is highly likely Covid-19 will become a “moving target” as more variants emerge across the world.

Professor John Wright, an epidemiologist and director of the Bradford Institute for Health Research at Bradford Royal Infirmary, has been writing a frontline diary for the BBC since the start of the pandemic. In his latest entry, he said it is becoming clearer that we are unlikely to reach zero Covid, but that it may become a feature of our lives, much in the same way as seasonal flu.

He said: “Just before Christmas I wrote about my surprise at having a possible reinfection with Covid. With 100 million people infected worldwide the number of reinfections appeared to be vanishingly small.”

Prof Wright said that when he received a positive PCR result, his first instinct was to assume his first antibody test, last summer, had found antibodies arising from common seasonal coronaviruses similar to Covid, not from Covid itself. But he said results from a recent national Siren study, spearheaded by infectious diseases expert Susan Hopkins, made him rethink.

Prof Wright said: “Healthcare workers were among the most at risk during the first wave, so provide a rich soup to study Covid infections. She and her team devised a study of 10,000 NHS staff to follow up for 12 months and as the urgency of the research grew, the study expanded to include 50,000 staff all across the UK. Those in the study, which is still continuing, get PCR and antibody tests for SARS-CoV-2 every two to four weeks. In the first set of results, published in January, about one-third of them turned out to have antibodies for the virus, confirming previous infection during the first wave of the pandemic, and the remaining two-thirds had remained clear of infection.”

The study found that almost one per cent of staff who had evidence of prior infection became reinfected in just the initial five months of the study.

While many had been asymptomatic in their first infection, around 2 per cent had a “full Covid syndrome” yet were reinfected.

Prof Wright said: “So the severity of the initial illness did not necessarily protect against subsequent infection. Crucially, the study also highlighted that previous infection did not prevent the risk of future transmission of the virus.”

He added: “These results are likely to be a precursor of what happens to our antibodies with vaccines, and so it is becoming clearer that we are unlikely to reach zero Covid. Rather, we will see ongoing outbreaks as our immunity waxes and wanes.

“One analogy being used foresees the current forest fire of cases becoming a bonfire, then a pile of smouldering embers, and after that just smoke - followed by small fires sparking up, perhaps in the winter months. Previous infection or vaccination will not necessarily protect you.

“It may become a feature of lives, like seasonal flu.”

Prof Wright said the Siren study will “be able to investigate the risk of reinfection with new variants such as the Kent variant and help us understand to what extent our immune response to one type of virus protects us against others”.

He added: “But it seems highly likely that as more variants emerge across the world, the genetic mutations in the virus will make it a moving target for our body’s defence system, and for vaccine manufacturers.”