A new study led by researchers at Imperial College London and the University of Padua shows that antibody levels remain high nine months after SARS-CoV-2 infection, whether the person was symptomatic or asymptomatic. The results of the study were published in the journal Nature Communications.
For the study, the team tested more than 85 percent of the 3,000 residents of Vo' in Italy in February/March 2020 for infection with SARS-CoV-2, the virus that causes COVID-19. They then tested them again in May and November 2020 for antibodies against the virus. Antibody levels were tracked using three assays; tests that detect different types of antibodies which respond to different parts of the virus.
As per the findings, 98.8 percent of people infected in February/March showed detectable levels of antibodies in November. The results also showed that there was no difference between people who had suffered symptoms of COVID-19 and those that had been symptom-free.
The team also investigated the infection status of household members, to estimate how likely an infected member is to pass on the infection within the household. Their modelling suggests that there was a probability of about 1 in 4 that a person infected with SARS-CoV-2 passes the infection to a family member and that most transmission is caused by 20 percent of infections.