How Long Does Your Immunity Last After Omicron?

(Photo: Onfokus via Getty Images)
(Photo: Onfokus via Getty Images)

With cases of Omicron increasing so quickly, many of us will have been infected with the variant by now. The latest data shows there are more than 212,00 daily cases of the strain in England alone.

We know that catching Covid gives you an immunity boost, and that getting vaccinated (and boosted) will give you a lot of protection from Covid, too.

So, does that mean we don’t have to worry about getting Covid if we’ve been boosted and had Omicron already? Before you run around feeling invincible, here’s what you really need to know.

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Catching Covid gives you an immunity boost

Coronavirus antibodies from natural infection can last for at least six months for the majority (88%) of people who have had the virus, according to a UK Biobank study of the original strain. Researchers said the results indicated antibodies produced following natural infection may “provide a degree of protection for most people”.

According to new analysis from the Zoe Covid Study app, 81% of participants who took an antibody test after a known Covid-19 infection tested positive for anti-N antibodies – the antibodies acquired from a natural infection, not vaccination.

Professor Paul Hunter, an expert in infectious diseases at the University of East Anglia says: “Infection – whether with Omicron or any other variant – will boost your immunity. That immunity will be better against the same variant but will also boost immunity to other variants though less powerfully. Against severe disease there is better cross immunity between variants than seen for cross immunity against mild infection.”

Being fully vaccinated gives you protection, but for how long?

Analysis from the Zoe Covid Study app, which invites users to log Covid-19 vaccines to monitor their side-effects and effectiveness, suggested the Pfizer jab was 88% effective at preventing Covid-19 infection a month after the second dose, but after five to six months, protection decreased to 74%.

The AstraZeneca vaccine offered 77% protection against infection one month after the second dose, but after four to five months, protection decreased to 67%.

But again, this data comes from the original strain of Covid. We know vaccines are less effective against the Delta and Omicron variants, which is why having a booster dose is key.

Watch: Why are millions of people not yet vaccinated against coronavirus?

Will the booster protect you from the Omicron variant?

Research shows that the booster jab does offer more protection. “All of the vaccines in our study do show a statistically significant boost,” said Professor Saul Faust, trial lead and director of the NIHR Clinical Research Facility at University Hospital Southampton NHS Foundation Trust.

The latest CovBoost trial, published in the Lancet, involved 2,878 people aged 30 or over who received a booster 10 to 12 weeks after their initial two jabs.

Although the newly emerged Omicron variant was not tested in the study, the study showed that booster vaccines are working well against existing variants.

“The data clearly shows that all boosters provided a lift to at least one aspect of your Covid immunity, and that side effects were, on the whole, mild,” Jonathan Ball, professor of molecular virology at the University of Nottingham, added.

Professor Chris Whitty, Chief medical officer for England, has also previously urged people to be boosted for better protection against Omicron.

“Boosters give you the best possible protection against the virus and should significantly reduce your risk of serious illness and hospitalisation,” he said. “Get your Covid-19 booster vaccine to strengthen your protection. Please, get boosted now.”

Can we catch the Omicron variant twice?

Sadly, the answer is yes, but Professor Hunter does add some reasons for optimism.

“We will be able to catch Omicron more than once, though subsequent infections will almost always be less severe than the first time round,” he says. “Most people who catch Omicron can probably look forward to at least a year before catching it again.”

It’s crucial to still show caution around Covid, though, as research is ongoing and as we’ve seen repeatedly, new variants can change the state of play very quickly.

“If another variant comes along during that time, that could still escape immunity from Omicron and cause an earlier infection,” Prof. Hunter adds.

“We have no data yet about whether having a booster and catching the Omicron virus give you more protection, but it almost certainly will.

The best evidence comes from the finding that people who have had two doses and had an infection have some of the best immunity on a par with people with three vaccine doses, especially against severe disease.”

This article originally appeared on HuffPost UK and has been updated.