Fact Check-Lower number of anti-N antibodies does not indicate lower immunity, say medical experts

Social media users have misinterpreted a British government report on COVID-19 vaccines, baselessly claiming that it proves vaccinations permanently lower an individual’s immunity to the disease.

The assertion rests on observations by the UK Health Security Agency that double-vaccinated people who later catch COVID-19 develop less ‘N antibodies’ than those who recover from the illness before their inoculations. (see page 23, here).

On Facebook, Twitter and one journalist’s blog, multiple people have since interpreted this finding to mean double-vaccinated individuals have less immunity overall to COVID-19 here, here, here and here).

“The British government has spilled the beans about that fact that once you get double jabbed, you will never again be able to acquire full natural immunity,” said one Facebook user, who added that vaccinated people would be “far more vulnerable” to future SARS-CoV-2 mutations.

The user added: “The unvaccinated, meanwhile, will procure lasting, if not permanent, immunity to all strains of the alleged virus after being infected with it naturally even just once.”

These assumptions are misguided, several medical experts have told Reuters.

"Although natural immunity gives broader protection against the virus, it’s not necessarily better,” said Professor Tim Spector, head of genetic epidemiology at King’s College London and lead scientist on the ZOE COVID Study app, one of the world’s largest ongoing studies of COVID-19 (

He explained that there are different types of antibodies that offer protection, none of which guarantees more or less immunity, with reinfection possible both after vaccination and natural infection.

“Anti-N antibodies are only produced if you’ve actually been infected with COVID-19 (natural infection). Anti-N antibodies recognise a molecule inside the SARS-CoV-2 virus called the nucleocapsid (N),” Spector said.

“Whereas, Anti-S antibodies look for the spike protein (S) on the surface of the virus; these antibodies can be present after both a natural infection and a vaccine. This is because COVID vaccines are based on the spike protein.”

Pointing Reuters to Zoe COVID study research, Spector added that anti-N antibodies are not guaranteed to develop in everyone who recovers naturally from COVID-19 (here). 

“Our latest analysis found that one in five ZOE Study participants who tested positive for COVID didn’t go on to have detectable anti-N antibodies afterwards,” he said.

Experts at Meedan Health Desk, a group of public health scientists working to tackle medical misinformation, affirmed Spector’s comments.

“Importantly, the anti-S and anti-N antibodies combined do not equal greater immunity against COVID-19,” they told Reuters in an email.

The experts added that early “viral neutralisation” through vaccination might modify the body’s response and limit the subsequent development of anti-N antibodies if infected after vaccination. However, this would not impact levels of immunity.

There are still many unknowns about immunity and COVID-19 variants. More research is being conducted to study protection from COVID-19 vaccines compared to prior infection.

Meedan Health Desk experts pointed Reuters to one recent study analysing hospitalised individuals who received a COVID-19 vaccine and those who had been infected with COVID-19 (here). They said it showed vaccine immunity was “more protective than ‘natural’ infection against COVID-19".

COVID-19 mRNA vaccines are also “about five times more effective” at preventing hospitalisation than a previous infection, they added.

Meanwhile, Zoe COVID Study data (here) suggests two doses of the AstraZeneca vaccine give 71% protection against infection, while two doses of the Pfizer vaccine give 87% protection.

By contrast, it suggests an unvaccinated person with a previous COVID infection has 65% protection against reinfection.


Misleading. While the UKHSA has observed lower anti-N antibodies in people who caught COVID-19 after double vaccination, this does not mean vaccines have hindered natural immunity to the disease.

This article was produced by the Reuters Fact Check team. Read more about our fact-checking work here .