Two thirds of the global population are likely to have COVID-19 antibodies from vaccination or infection, according to a new World Health Organization study.
Research carried out by WHO’s Unity Studies and SeroTracker suggests that, based on seroprevalence, global COVID-19 infection rates are likely to be higher than previously reported.
Writing in the latest PLoS Medicine, the authors say routine surveillance data underestimate infection and cannot infer population immunity because of asymptomatic infections and uneven access to diagnostics.
To try to establish the true rates of infection and indicators of immunity in the population, they carried out a systematic review and meta-analysis of seroprevalence studies published from January 2020 to May 2022.
They identified 965 distinct seroprevalence studies, 43% of which were from low-middle income countries, sampling 5,346,069 participants between January 2020 and April 2022.
When the team analysed seroprevalence by country and month, estimating regional and global seroprevalence over time, and estimated seropositivity rates from infection versus infection or vaccination, they found global seroprevalence had risen from 7.7% in June 2020 to 59.2% in September 2021.
This, they say, suggests two thirds of the global population may be SARS-CoV-2 seropositive from either vaccination or infection, adding that estimates of COVID-19 infections based on seroprevalence data far exceed reported cases.
The authors write: “This study on global seroprevalence of SARS-CoV-2 antibodies found that while seroprevalence has increased over time, a third of the global population tested negative for antibodies against the virus as of September 2021 estimates. It was also found that compared to seroprevalence estimates, routine testing for COVID-19 has largely underestimated the number of global infections.”
They add: “As we enter the third year of the COVID-19 pandemic, implementation of a global system or network for targeted, multi-pathogen, high-quality and standardised collaborative serosurveillance is a crucial next step to monitor the COVID-19 pandemic and contribute to preparedness for other emerging respiratory pathogens.”
The publication also carries results from a German study that shows adults and children have at least a 30% greater risk of developing health problems after having COVID-19.
Research by Martin Roessler of Technische Universität Dresden, and colleagues found that children and adolescents who had been infected with COVID-19 were 30% more likely than those who had not had the virus to have documented health problems three months or more after infection.
Adults who had had COVID-19 were 33% more likely than controls to have health problems, says the study, published in PLoS Med.
They analysed a healthcare dataset, which covers almost half of the German population, for all of 2019 and 2020, identifying individuals who had confirmed COVID-19 via a PCR test.
They went on to compare the occurrence of pre-specified diagnoses that were entered into the medical record at least three months post-infection, in the 11,950 children and adolescents and 145,184 adults who’d had COVID-19 with a matched control cohort of more than 750,000 individuals who did not have PCR-confirmed COVID-19.
Among children and adolescents, rates of fatigue/exhaustion, cough and throat, and chest pain were the most strongly associated with a prior COVID-19 infection, but rates of headache, fever, abdominal pain, anxiety disorder and depression were also increased.
In adults, smell/taste disturbance, fever, and dyspnoea were most strongly associated with COVID-19 infection, but other common complaints included cough, throat and chest pain, hair loss, fatigue, exhaustion and headache.
Bergeri I, Whelan M, Ware H et al. Global SARS-CoV-2 seroprevalence from January 2020 to April 2022: A systematic review and meta-analysis of standardized population-based studies. PLoS Med 10 November 2022 [abstract]
Roessler M, Tesch F, Batram M et al. Post-COVID-19-associated morbidity in children, adolescents, and adults: A matched cohort study including more than 157,000 individuals with COVID-19 in Germany. PLoS Med 10 November 2022 [abstract]
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