Case 1 had high anti-spike IgG detected on day 3 of the illness, with low neutralizing antibody activity

Case 1 had high anti-spike IgG detected on day 3 of the illness, with low neutralizing antibody activity. The neutralizing antibody activity started to increase on day 5 of the illness. In Case 2 both the anti-spike IgG and Phentolamine mesilate the neutralizing antibody activity remained low from days 4C11 of illness, and the anti-spike IgG gradually increased from day 9. In Case 1, the fever broke within 4 days of onset, coinciding with the rise in neutralizing antibodies, whereas the fever took 7 days to resolve in Case 2. SARS-CoV-2 infection can occur even in vaccinated individuals, but vaccination may contribute to milder clinical symptoms because neutralizing antibodies are induced earlier in vaccinated individuals than in unvaccinated individuals. strong class=”kwd-title” Keywords: SARS-CoV-2 infection, Delta variant, Breakthrough infection, BNT162b2 vaccine, Anti-spike IgG, Neutralizing antibodies strong class=”kwd-title” Abbreviations: COVID-19, coronavirus disease 2019; IgG, immunoglobulin G; PCR, polymerase chain reaction; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2; SpO2, peripheral oxygen saturation; TCID50, median tissue culture infectious dose 1.?Introduction Since the initial reports of coronavirus disease 2019 (COVID-19) from Wuhan, China in December 2019, COVID-19 has become pandemic. In Japan, between the first case of COVID-19 diagnosed in January 2020 and November 19, 2021, 1.7 million cases, including 1,800 deaths, were reported [[1], [2], [3]]. Several variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of COVID-19, have emerged, and as of November 2021, the delta variant has become the predominant variant in many countries, including Japan [2]. The delta variant is reported to be more transmissible and some reports suggest that the delta variant causes more severe disease than the wild-type and alpha variant [4,5]. Vaccination is expected to play an important role in controlling the COVID-19 pandemic, and the rollout began in February 2021 in Japan. Messenger RNA vaccines has been found to be highly effective at preventing asymptomatic SARS-CoV-2 infection, symptomatic infection, and severe COVID-19 [6]. Although breakthrough infections, which are defined as SARS-CoV-2 infections occurring at least 2 weeks after an individual has been fully vaccinated [7], have been reported [8], there are limited data on the antibody response, including the anti-SARS-CoV-2 neutralizing antibody activity, and the clinical course in individuals with breakthrough infections. Here, we report a case of breakthrough infection with the SARS-CoV-2 delta variant, and a secondary case in a family member (in which the index case was fully vaccinated and the secondary case had not been vaccinated) with the clinical role of the anti-spike immunoglobulin G (IgG) and neutralizing antibody activity. 2.?Case report 2.1. Case 1 A 31-year-old healthy female healthcare worker (physician, not involved in the treatment of COVID-19) presented to our hospital with a three-day history of fever, nasal discharge, Phentolamine mesilate and cough, complaining of malaise and breathing difficulty. She had received two doses of BNT162b2 mRNA COVID-19 vaccine (Pfizer-BioNTech), administered 109 days and 88 days before the onset of her symptoms. Her body temperature was 36.9?C, her respiratory rate was 18/minutes, and her peripheral oxygen saturation (SpO2) was 99% breathing room air. Blood tests revealed increased C-reactive protein (4.4 mg/dL), but no other abnormalities were found. She did not have any signs of pneumonia on chest radiography. A nucleic acid amplification test (ID Now SARS-CoV-2, Abbott, Chicago, Mouse monoclonal to CK16. Keratin 16 is expressed in keratinocytes, which are undergoing rapid turnover in the suprabasal region ,also known as hyperproliferationrelated keratins). Keratin 16 is absent in normal breast tissue and in noninvasive breast carcinomas. Only 10% of the invasive breast carcinomas show diffuse or focal positivity. Reportedly, a relatively high concordance was found between the carcinomas immunostaining with the basal cell and the hyperproliferationrelated keratins, but not between these markers and the proliferation marker Ki67. This supports the conclusion that basal cells in breast cancer may show extensive proliferation, and that absence of Ki67 staining does not mean that ,tumor) cells are not proliferating. IL, USA; ID now) revealed that she had breakthrough SARS-CoV-2 infection. She was admitted due to fatigue and fever but did not require supplemental oxygen. Her fever subsided on the fourth day of the illness, and she was discharged on the tenth day of the illness. 2.2. Case 2 Because Case 1 was diagnosed with COVID-19, her close contacts, including her husband, were tested for SARS-CoV-2. All 17 close contacts were asymptomatic, and had negative polymerase chain reaction (PCR) results on the initial test. However, on the fifth day after the onset of Case 1, her husband, a healthy 33-year-old male who had not been vaccinated, developed fever, and a PCR test performed the next day was positive. He was Phentolamine mesilate admitted to our hospital because of fever and fatigue. On the day of admission Phentolamine mesilate (day time 2 after onset), his body temperature was 39.0?C, his respiratory rate was 20/moments, and his SpO2 was 97% deep breathing room air. Blood tests exposed no abnormalities. Although he did not possess pneumonia on lung computed tomography check out, his body temperature remained over 38.0?C, he had persistent cough, and his SpO2 decreased to 95% after admission. He was treated with remdesivir, starting 5 days after the onset. His fever subsided 7 days after.