Evaluation of anti-nucleocapsid antibody seropositive after SARS-CoV-2 infection in vaccinated individuals

The pandemic of Coronavirus Disease 2019 (COVID-19) caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) continues to cause adverse health effects for millions of people around the world. ..

Distant and recent infections that may help determine infection status in clinical trials of vaccines, enable population-based seroprevalence studies, and diagnose post-SARS-CoV-2 complications You need a reliable diagnostic tool to identify.

One such approach is to identify the presence of antibodies against the nucleocapsid protein (anti-N antibody) and confirm SARS-CoV-2 infection. Anti-NAbs are not induced by the COVID-19 vaccine and several studies have reported that they have high specificity and sensitivity. In addition, anti-N antibodies have been reported to be durable to unvaccinated individuals with a half-life of 68-283 days. However, it is still unclear whether seroconversion to non-spike proteins is affected by vaccine-induced immunity and whether immunoassays accurately measure non-spike seroconversion in high-vaccination areas.

New research published in Annual report of internal medicine The journal evaluated recipients of both placebo and vaccine in a phase 3 clinical trial of mRNA-1273 (Moderna) infected with SARS-CoV-2 in a blinded placebo-controlled trial phase. Serum samples were collected from all participants and assayed for the presence of anti-NAbs 5 months after enrollment.

About research

The survey was conducted between July 27 and October 23, 2020 and included individuals over the age of 18. Participants were randomly assigned to receive 100 micrograms of either placebo or the mRNA-1273 vaccine on day 1 (baseline) and day 29.

SARS-CoV-2 infection was detected based on symptomatic and planned tests at specific study visits. Blood samples were collected from all participants on days 1, 29, and 57, and at the Participant Decision Visit (PDV), participants were informed about the trial assignment. In addition, nasopharyngeal or saliva samples were collected on days 1 and 29, and PDV was collected for the SARS-CoV-2 test. The occurrence of PDV was about 149 days after registration.

Information on the severity of symptoms, Oxygen saturationAnd body temperature collected for 14 days Via telemedicine.. Detection of anti-NAbs was performed with the help of the Elecsys Anti-SARS-CoV-2 immunoassay.

In addition, four mutually exclusive infection groups were defined based on the timing and method of SARS-CoV-2 detection. The first group included COVID cases detected from at least 14 days after dosing 2 to PDV. The second group consisted of participants who were positive or positive for anti-N sera. Nasopharyngeal swab At baseline. The third group consisted of participants who were positive for anti-N sera on day 29, but had no previous evidence of infection. The fourth group consisted of participants who were seronegative on day 29 and positive for nasopharyngeal swabs on day 29, but had no previous evidence of infection.

Survey results

The results reported SARS-CoV-2 infection within 14 days or more after administration of the vaccine or placebo in 812 participants who were SARS-CoV-2 negative participants at baseline. The infection was detected either by anti-N sera positive or nasopharyngeal swab RT-PCR positive. The time from the second dose to illness was reported to be 77 in the vaccine group and 73 in the placebo group.

COVID-19-positive participants on illness visits were found to have 93.4% anti-N seropositive in PDV for placebo recipients and 40.4% for vaccine recipients. Anti-N seropositive in PDV is associated with PDV and the number of days between disease or age, gender, race, classification of obesity index, and risk of severe COVID-19 in both placebo and vaccine recipients. I didn’t understand. However, for vaccinated people, there was a positive correlation with the number of days between illness and the second vaccination.

In addition, anti-N serum positivity was found to be 13.67 times higher in the placebo group compared to the vaccine group with any SARS-CoV-2 virus level. Anti-N seroprevalence was observed to be 96.1% in the vaccine group and 95.1% in the placebo group maintained through PDV. For participants who were baseline anti-N seronegative and PCR positive, day 29 anti-N seropositive in the placebo group was observed to be 74.1% and 73.3% in the vaccine group.

Overall, PDV and day 29 anti-N seroprevalence were found to be lower in patients with PCR positive at baseline than in patients with anti-N seropositive. Similar observations were made for anti-N seroprevalence on day 57 and PDV in anti-N seronegative and PCR-positive participants on day 29 compared to participants who were anti-N seropositive.

Therefore, this study found that seroconversion occurred more frequently in in-situ recipients compared to vaccine recipients. Further research is needed to identify population-level SARS-CoV-2 infections. In addition, vaccination status should be considered when interpreting seroprevalence and seroprevalence data at the individual and population levels.

Limitations

There are certain restrictions on this study. First, this study covers only one vaccine and does not consider whether other COVID-19 vaccines also interfere with post-infection anti-N seropositive. Second, the study considered the Elecsys assay, the only immunoassay. Third, the sample size was small. Fourth, it was not clear whether the anti-N antibody seroconversion rate would increase or decrease depending on the vaccination status and serious illness. Fifth, the effect of breakthrough infection with delta or omicron variants on seroconversion rates could not be determined. Finally, this study failed to address the objectives of coronavirus efficacy testing.