The immunology of SARS-CoV-2 infections and vaccines

Abstract

SARS-CoV-2, the virus that causes COVID-19, emerged in late 2019, and was declared a global pandemic on March 11th 2020. With over 50 million cases and 1.2 million deaths around the world, to date, this pandemic represents the gravest global health crisis of our times. Thus, the race to develop a COVID-19 vaccine is an urgent global imperative. At the time of writing, there are over 165 vaccine candidates being developed, with 33 in various stages of clinical testing. In this review, we discuss emerging insights about the human immune response to SARS-CoV-2, and their implications for vaccine design. We then review emerging knowledge of the immunogenicity of the numerous vaccine candidates that are currently being tested in the clinic and discuss the range of immune defense mechanisms that can be harnessed to develop novel vaccines that confer durable protection against SARS-CoV-2. Finally, we conclude with a discussion of the potential role of a systems vaccinology approach in accelerating the clinical testing of vaccines, to meet the urgent needs posed by the pandemic.

COVID-19 re-infection in Shahroud, Iran: a follow-up study

“…But the remarkable point was the younger age range (between 21-60 years) that other studies have reported in re-infection of Covid-19 [8,21,22]. Due to the fact that seroconversion is observed in most patients with SARS-COV-2, however, the titer of binding and neutralizing antibodies is very variable between different individuals and decreases over time [16]. It has also been reported that people with more severe disease have higher levels of neutralizing antibody titers, and that antibody levels are still detectable 2 to 3 months after primary symptoms, while those who were asymptomatic or had mild symptoms, had lower antibody titers, and in less than two months the antibodies started to decrease [23] Although one study showed that these antibodies can protect against re-infection for several months after infection, the exact titer of antibodies needed to neutralize the virus to prevent re-infection must be determined [4].…”

Assessment of automated high-throughput serological assays for prediction of high-titer SARS-CoV-2 neutralizing antibody

“…Except for ABB, the remaining four tests target the viral receptor S protein as a whole or as one or both subunits. ABB uses the nucleocapsid protein as its target antigen, Abs against which appear first and in higher amounts compared to S protein [ 2 , 3 ]. This test is used to identify SARS-CoV-2 seropositive donors by the Italian blood bank service.…”

“…Since the beginning of the SARS-CoV-2 pandemic, COVID-19 can be seen as an unusual infection. Although it tends to be more serious in certain categories of patients, there is little correlation between clinical course of infection and antibody levels reached after convalescence [1] , [2] , [3] , [4] . Indeed, longitudinal surveys have demonstrated that antibody responses mount earlier in severe COVID patients.…”

Population Age-Ineligible for COVID-19 Vaccine in the United States: Implications for State, County, and Race/Ethnicity Vaccination Targets

“…Preliminary research on cellular immunity from natural infection suggests the possibility of lasting protection; 27,28 however, immune memory from infection has proven variable. In the absence of robust longitudinal data, a clear understanding of the mechanisms of humoral and cellular immune responses remains incomplete 29 Because of these uncertainties, the CDC currently recommends that everyone who is age-eligible should be vaccinated, including individuals who have previously tested positive for the virus and/or survived clinical COVID-19 illness. 30 Differences in the age structure of racial/ethnic population groups will impact the success of COVID-19 vaccination programs.…”