As the world learns to maneuver the COVID-19 pandemic, scientists continue to conduct their researches on the virus’ epidemiology. This was also the goal of a study conducted on the residents of an Italian city called Vo’, that aimed to see if the people who were infected with COVID-19 in February/March of 2020 still had a detectable antibody count against the virus in November. It was led by a joint team of researchers from the University of Padua and Imperial College London.
According to the article, published in Nature Communications, the team tested 85% of Vo’s residents at the start of the pandemic. They retested these participants in November and found that the overall antibody count had decreased. However, 98.8% still had detectable antibody levels. They also found that the amount of antibodies did not differ between symptomatic and asymptomatic cases of COVID-19. This means that the infection’s severity does not influence the immune response.
Furthermore, some people even had increased antibody levels in November, indicating that reinfection does produce an immune-boosting response.
The team had used three different assays to confirm their antibody analysis. Each assay detected a different type of antibody, which meant that each test gave a different count.
“This means that caution is needed when comparing estimates of infection levels in a population obtained in different parts of the world with different tests and at different times,” explained lead author Dr. Ilaria Dorigatti of the MRC Centre for Global Infectious Disease Analysis and the Abdul Latif Jameel Institute for Disease and Emergency Analytics (J-IDEA) at Imperial College.
The team further analyzed the domestic spread of the virus between members of the same house. They found that 1 in 4 infected people passed the virus on. According to their epidemiological model, only 20% of the infected patients were passing on the majority of the infection. This finding brings back into perspective how social behavior is the key to ending this worldwide crisis.
Finally, the authors also considered the different measures used to control the virus’ spread.
Professor Andrea Crisanti, Department of Life Sciences at Imperial College / Department of Molecular Medicine at the University of Padua.
“Our study also shows that manual contact tracing – the search for positive individuals on the basis of known and declared contacts – would have had a limited impact on the containment of the epidemic, had it not been accompanied by a mass screening.”
Source: Imperial College London