Universal Covid vaccine ‘urgently needed,’ scientists warn

A universal Covid jab is “urgently needed,” scientists have warned after a study confirmed prior infection or vaccination offers only limited protection against new variants.

Variants such as Delta and Omicron are “genetically distinct” from previous forms of the virus and can be transmitted even to people who have been vaccinated or have previously had Covid, researchers found.

The waves were driven by the original Covid-19 virus and Beta, Delta and Omicron, three variants listed as of variants of concern (VOCs) by health authorities.

The team at Columbia University Mailman School of Public Health in New York said their model accurately predicted the trajectories of cases and deaths in most of the nine provinces, as well as retrospectively predicted the Delta and Omicron waves before the real-life peak of cases and deaths linked to these VOCs.

The researchers then used their model to estimate each variant’s characteristics, including the infection-detection rates, infection-fatality rates, and population susceptibility and transmissibility – before comparing these across the provinces.

The estimates were then used to quantify the erosion of immunity and the increase in transmissibility for each VOC.

Study author Dr Wan Yang, assistant professor of epidemiology at the Columbia University Mailman School of Public Health in New York, said: “These repeated pandemic waves have been driven by new VOCs that erode prior immunity from either infection or vaccination, increase transmissibility, or a combination of both.

“Although laboratory and field studies provide insights into variant epidemiological characteristics, quantifying the extent of immune erosion and changes to transmissibility for each VOC is challenging.”

A universal vaccine could block infection and prevent severe disease, he and co-author Dr Jeffrey Shaman have suggested.

The team found that Beta eroded immunity among 65 per cent of people previously infected by the original Covid-19 and was 35 per cent more transmissible in comparison.

Delta estimates varied between provinces, but the scientists said that the variant eroded immunity from prior infection or vaccination by about 25 per cent and was 50 per cent more transmissible, while Omicron eroded immunity from prior infection or vaccination by 55 per cent and was roughly 95 per cent more transmissible.

Prior immunity to Covid-19 does not preclude outbreaks caused by new VOCs, the team concluded adding that neither prior infection nor vaccination completely blocks infection from new variants.

The authors of the study, published in the journal eLife, said this meant a “universal vaccine that can block SARS-CoV-2 infection, and prevent severe disease, is urgently needed”.

Efforts to design universal vaccine which would remain effective in the face of frequent mutations have so far proved largely fruitless.

But researchers in the UK last month hailed a “promising” breakthrough in the race to develop a “holy grail” vaccine that can offer protection against multiple Covid variants and a variety of common colds caused by other coronaviruses.

Scientists at the Francis Crick Institute believe they have identified a genetic feature of Sars-CoV-2 that appears to be “similar” across a number of coronaviruses and is less prone to mutations, making it a potential target for a pan-coronavirus, or universal, vaccine.