Scientists have warned a new wave of infections has begun as two Covid sub-variants have led to a spike in cases.
More than 3.8 million people in the UK now have the virus, a weekly increase of 7 per cent, according to the latest figures from the Office of National Statistics (ONS).
This increase is largely due to the Omicron variants BA.4 and BA.5, according to the ONS.
More than two years after the first cases in Britain, millions of Britons have contracted the virus and some will have had it multiple times.
But how likely is reinfection and how much protection do vaccines and boosters offer?
Here’s everything you need to know.
When the Omicron variant arrived in the UK last December, the reinfection rate increased 15-fold.
Omicron’s extensive mutation allowed the virus to overcome any established immunity, scientists believe.
That’s why so many vaccinated or sick people got infected again during the Christmas season.
So said Danny Altmann, Professor of Immunology at Imperial College London The guardOmicron is “weakly immunogenic, meaning capture offers little additional protection against reinfection.”
Although the new BA.4 and BA.5 variants are from the Omicron lineage, “there is now further evidence of the very marginal ability of the earlier Omicron to prime any immune memory for either BA.4 or BA.5,” Professor said Altmann.
This suggests that even if you had Omicron during the Christmas and New Year’s wave, it’s still possible that you could contract the virus again.
Professor Tim Spector, who runs the ZOE Covid app, said The guard: “There are definitely a lot of people who got Covid earlier in the year who are getting it again, including some with BA.4/5 who had BA.1/2 just four months ago who thought they were protected.”
However, the professor added that being infected with Covid again within three months was “rare”.
The new BA.4 and BA.5 variants contain mutations not present in the early strains of Omicron.
So even if you have been vaccinated and given a booster shot, you are still susceptible to the new subvariants.
Researchers from China report this in the journal Nature that the new subvariants “particularly evade the neutralizing antibodies elicited by SARS-CoV-2 infection and vaccination.”
Vaccine boosters based on the BA.1 virus, such as those being developed by Pfizer/BioNTech and Moderna, “may not achieve broad-spectrum protection against new Omicron variants,” the researchers warned.
“My personal bias is that while an Omicron-specific vaccine may have some benefits, I believe it will only have marginal benefit over the existing vaccines and boosters,” said Dr. Onyema Ogbuagu, an infectious disease researcher at Yale School of Medicine in New Haven, Connecticut.
“Despite immune evasion, vaccines can still be expected to protect against serious diseases,” said Dr. Ogbuagu.
“When a refresher is due, get a refresher. What we have learned clinically is that the most important thing is to stay current on vaccines.”
In general, infections tend to become milder the second or third time due to the residual immunity the body develops.
However, according to preliminary data from University of Tokyo professor Kei Sato and colleagues, the new subvariants may have evolved to favor infection of lung cells rather than upper respiratory tract tissue.
This makes them more similar to the earlier and stricter Alpha and Delta variants.
dr Stephen Griffin, a virologist at the University of Leeds, said: “It looks like these things are switching back to the more dangerous form of infection, which is going deeper into the lungs.”
Although it’s too early to tell if symptoms will become more aggressive in reinfection cases, the risk of these new Omicron variants is “potentially greater than that of the original BA.2,” Professor Sato said.