Cookies on this website

We use cookies to ensure that we give you the best experience on our website. If you click 'Accept all cookies' we'll assume that you are happy to receive all cookies and you won't see this message again. If you click 'Reject all non-essential cookies' only necessary cookies providing core functionality such as security, network management, and accessibility will be enabled. Click 'Find out more' for information on how to change your cookie settings.

BackgroundWe have investigated the reinfection rate of vaccinated or convalescent immunized SARS-CoV-2 in 952 expatriate workers with SARS-CoV-2 serological antibody patterns and surrogate T cell memory at recruitment and follow up.MethodsTrimeric spike, nucleocapsid, and neutralizing antibodies were measured along with a T cell stimulation assay targeting SARS-CoV-2 memory in CD4+ and CD8+ T cells. The subjects were then followed up for reinfection for up to six months.ResultsSeroprevalence positivity at enrollment was greater than 99%. T cell reactivity in this population was 38.2%. Of the 149 (15.9%) participants that were re-infected during the follow up period (74.3%) had nonreactive T cells at enrollment. Those who had greater than 100 BAU/mL increase from the median concentration of Anti-S IgG antibodies had a 6% reduction in the risk of infection. Those who were below the median concentration had a 78% greater risk of infection.ConclusionsSignificant immune protection to reinfection was observed in those that retained T cell activation memory. Additional protection was observed when Anti-S was greater than the median value.

Original publication




Journal article


International journal of infectious diseases : IJID : official publication of the International Society for Infectious Diseases

Publication Date



National Reference Laboratory, Abu Dhabi, United Arab Emirates; Faculty of Medicine, Ain Shams University, Cairo, Egypt. Electronic address: