Trajectory patterns of SARS-CoV-2 neutralising antibody response in convalescent COVID-19 patients

Plain language summaryNeutralising antibodies are produced by the immune system and help to defend against viruses like SARS-CoV-2, which causes COVID-19. Declining levels of these antibodies over time might be linked to risk of re-infection with the virus. Here, we look at changes in neutralising antibody levels over time in people who have had COVID-19. We define two classes of people: those with persistently high levels of antibodies over time, who are more likely to be older and have chronic illnesses, and those with declining antibody levels, who are younger and had mild COVID-19 symptoms. Understanding differences in how these antibodies are maintained over time in different groups of people might help to guide vaccination strategies to prevent re-infection. BackgroundThe adaptive immune responses of COVID-19 patients contributes to virus clearance, restoration of health and protection from re-infection. The patterns of and the associated characteristics with longitudinal neutralising antibody (NAb) response following SARS-CoV-2 infection are important in their potential association with the population risks of re-infection.MethodsThis is a longitudinal study with blood samples and clinical data collected in adults aged 18 or above following diagnosis of SARS-CoV-2 infection. NAb levels were measured by the SARS-CoV-2 surrogate virus neutralisation test (sVNT). Anonymous clinical and laboratory data were matched with surveillance data for each subject for enabling analyses and applying latent class mixed models for trajectory delineation. Logistic regression models were performed to compare the characteristics between the identified classes.ResultsIn 2020-2021, 368 convalescent patients in Hong Kong are tested for NAb. Their seroconversion occur within 3 months in 97% symptomatic patients, the level of which are maintained at 97% after 9 months. The NAb trajectories of 200 symptomatic patients are classified by the initial response and subsequent trend into high-persistent and waning classes in latent class mixed models. High-persistent (15.5%) class patients are older and most have chronic illnesses. Waning class patients (84.5%) are largely young adults who are mildly symptomatic including 2 who serorevert after 10 months.ConclusionsCharacteristic sub-class variabilities in clinical pattern are noted especially among patients with waning NAb. The heterogeneity of the NAb trajectory patterns and their clinical association can be important for informing vaccination strategy to prevent re-infection. Wong, Lee et al. analyse trajectory patterns in the neutralising antibody response to SARS-CoV-2 in convalescent COVID-19 patients. The authors identify two major classes of patients-high-persistent and waning-reporting specific clinical characteristics of each class, which could help with targeted vaccination strategies.