Do more than half of Nigerians have Covid-19 antibodies, as newspaper claimed? Study didn’t quite say that

We do not have data that supports the paper’s estimate of 50%. But even if this share were accurate, does it mean that half of Nigerians have survived Covid-19, as the Guardian asserted?

This was accurate, Mirabeau Tatfeng, a professor of medical microbiology and immunology at Niger Delta University, told Africa Check.

“The presence of antibodies is evidence that the person was exposed to the virus and if the person didn’t die, it means they survived it, whether the person was ill or asymptomatic,” Tatfeng said.

He said NCDC records for example indicated a survival rate of over 80%, with about 3,000 deaths from 250,000 cases. Studies have shown that many cases were not reported, and that testing was low in Nigeria, with only 5 million samples tested for an estimated population of 216 million. 

But Tatfeng added that many studies had not included children, so their results might not apply to all Nigerians.

Interpreted directly, this claim by the Guardian is correct. 

All the experts did however warn that the presence of antibodies didn’t mean a person couldn’t be infected in the future.

Antibodies ‘wane over time’, don’t guarantee protection 

“Only those who were down with Covid-19 to the extent of getting hospitalised would develop strong antibodies,” Tomori said. “But then antibodies wane over time. That you have developed antibodies does not mean you will always be protected from the virus.”

But a high level of antibodies could reduce the severity of infection.  

Also, most of the people exposed in Nigeria were asymptomatic, professor of public health Tanimola Akande told Africa Check. In an April 2022 statement the WHO said this was the picture across Africa.

The antibody levels of asymptomatic patients “may not be high enough to prevent infection among them”, Akande said. “It is therefore important for people to take the necessary doses of vaccination.”

By 7 May 2022 only 14% of Nigerians – 16 million – had been fully vaccinated. Across Africa, the figure is less than 15%.

Tomori added that the prevalence of antibodies should not be interpreted as herd immunity in Nigeria as this was “complicated”. 

Herd immunity is the indirect protection from an infectious disease when a population is immune either through vaccination or immunity developed from previous infection.

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